The impact of the tracheal length/length of the narrow segment ratio on surgical success in patients with subglottic stenosis

Introduction

Laryngotracheal stenoses (LTS) constitute a heterogeneous group of disorders, defined by the narrowing of the airway lumen diameter at the glottic, subglottic, or tracheal levels due to idiopathic or secondary factors (1). Besides the most common cause, i.e., prolonged intubation, other etiological factors include trauma, corrosive substances, surgical errors, and congenital factors. The idiopathic subgroup affects females within the age range of 20–40 years, and these patients are often misdiagnosed for years and treated under the presumptive diagnosis of asthma and other airway diseases (1-3). LTS was first described by MacEwen in 1880 in patients who underwent endotracheal intubation (4). While prolonged endotracheal intubation is the most common cause, other factors such as trauma, inflammatory conditions, and idiopathic causes can also lead to LTS (5-8). Recent studies still report rates of post-intubation subglottic stenosis (SGS) as high as 11% in selected populations (9). Among intubated patients, the incidence of LTS varies between 1% and 11%, with symptomatic stenosis occurring in only 1–2% of these cases (8,10). LTS surgery aims to re-establish a sufficiently wide lumen in the laryngotracheal system, thereby restoring the sphincter and phonation functions of the larynx. This study aimed to evaluate the outcomes of patients who underwent tracheal resection and anastomosis (TRA) for post-intubation subglottic stenosis. Although multiple factors influence surgical success in laryngotracheal reconstruction, the prognostic value of anatomical proportions—such as the tracheal length (TL) to length of the narrow segment (LNS) ratio—remains poorly understood. One important determinant of surgical success is anastomotic tension, which is directly influenced by the length of the resected tracheal segment. A higher TL/LNS ratio may reduce anastomotic tension, facilitate healing, and improve surgical outcomes—forming the basis of our hypothesis.

The primary aim of this study was to evaluate the clinical outcomes of patients undergoing TRA for post-intubation subglottic stenosis, with a particular focus on the impact of the TL/LNS ratio on surgical success, which was defined as decannulation in the absence of stridor at 12 months. The secondary aim was to investigate clinical and radiological factors associated with restenosis, identify risk factors, and evaluate patient characteristics that may serve as prognostic indicators. Identifying these variables could support more personalized treatment strategies, improve postoperative recovery, and reduce morbidity in this patient population.

Methods

Patients

The study was performed at the Department of Otorhinolaryngology, Gaziantep University Faculty of Medicine, a tertiary referral center specializing in airway surgery, and included only patients with post-intubation subglottic stenosis. Patients who underwent surgery for post-intubation SGS between 2009 and 2022 were retrospectively identified. Inclusion criteria included: adult patients with confirmed subglottic stenosis secondary to prolonged intubation and availability of complete clinical and radiological records. Exclusion criteria included: age under 18 years, history of prior tracheal surgery, or insufficient imaging. Stenosis grading was performed using the Cotton-Myer classification under general anesthesia with an uncuffed endotracheal tube. Stenosis diameter (SD), total TL, and LNS were measured using computed tomography (CT) imaging and direct laryngoscopy. All surgeries were performed by a single experienced airway surgeon at a tertiary care center, ensuring procedural consistency. Segmental tracheal resection of the stenotic segment was performed, followed by end-to-end anastomosis using absorbable sutures [polydioxanone suture (PDS) or polyglactin; Ethicon, USA]. No stents were used. A protective chin-to-chest suture was applied intraoperatively to reduce anastomotic tension. Postoperatively, patients were monitored in the intensive care unit and extubated within 24–48 hours, depending on airway stability. All patients remained in the hospital for at least 1 week. In tracheostomized patients, decannulation was performed after confirming airway patency via endoscopic examination. Patients without postoperative complaints were re-evaluated with fiberoptic endoscopy, and the chin sutures were removed prior to discharge. All patients were followed up for 12 months. Restenosis was defined as the recurrence of airway narrowing requiring intervention. Surgical success was defined as decannulation without stridor at final follow-up. In cases of restenosis, additional endoscopic interventions were applied. The patients were followed up for 1 year after surgery and were divided into two groups: those who developed restenosis and those who did not. Decannulated patients without active stridor complaints were considered successful at the end of the 1-year postoperative follow-up. For the group of patients who underwent additional interventions due to restenosis, TRA was considered successful for patients who were ultimately decannulated and had no active complaints. All procedures were performed by a single experienced airway surgeon at a tertiary care center, ensuring consistency in surgical approach and postoperative management. This was a retrospective observational study and is reported according to the STROBE reporting guidelines (available at https://www.theajo.com/article/view/10.21037/ajo-24-75/rc). The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by Gaziantep University Clinical Research Ethics Committee (Approval Number: 376). Because of the retrospective nature of the research, the requirement for informed consent was waived. Surgical technique was as follows: surgical technique was standardized in all patients. Segmental tracheal resection of the stenotic segment was performed, followed by primary end-to-end anastomosis. No stents were used. In patients with preexisting tracheostomy, the stoma was incorporated into the resection. A protective chin-to-chest suture was applied intraoperatively to reduce anastomotic tension. Absorbable suture material (e.g., PDS or polyglactin) was used in all anastomoses. Postoperatively, patients were monitored in the intensive care unit. Most patients were extubated within 24–48 hours following confirmation of airway stability. In patients with preexisting tracheostomy, the stoma was included in the resected segment; however, in selected cases where intraoperative or postoperative airway stability could not be ensured, a new tracheostomy was created distal to the anastomotic site. Decannulation was then performed after confirmation of airway patency via endoscopic evaluation during follow-up.

Statistical analysis

All statistical analyses were conducted using SPSS for Windows, version 22.0. Normality of the data was assessed using the Shapiro-Wilk test. For variables following a normal distribution, results are presented as mean ± standard deviation and compared using the Student’s t-test. Non-normally distributed variables are reported as median [interquartile range (IQR)] and analyzed using the Mann-Whitney U test. Categorical variables were compared using the Chi-squared test, and associations are presented with odds ratios (ORs)and 95% confidence intervals (CIs) where applicable. Spearman’s rank correlation test was used to assess relationships between non-normally distributed numerical variables. A P value <0.05 was considered statistically significant. Missing data were excluded from the respective analyses.

Results

There were a total of 40 patients, 75.0% (n=30) of whom were male and 25.0% (n=10) were female. Patients’ ages ranged between 18 and 72 years, with a mean age of 37.45±16.69 years. The duration of intubation varied between 5 and 90 days, with a mean duration of 23.43±20.65 days. The mean TL was 107.75±7.42 mm, LNS was 23.55±4.75 mm, and SD was 5.2±2.22 mm. The mean TL/LNS ratio was 4.8±1.33 (Table 1).

Of the 40 patients, 10 (25.0%) were smokers. Twelve patients (30.0%) required tracheotomy during the preoperative period. Preoperative tracheostomies were placed due to airway compromise in most cases, not as elective surgical access. No patient without a preoperative tracheostomy required intraoperative or postoperative tracheostomy. Patients were graded according to the Cotton-Myer classification in the preoperative period. Nineteen patients (47.5%) were classified as grade II, 18 (45.0%) as grade III, and 3 (7.5%) as grade IV (Table 2). Complications occurred in 6 (15.0%) patients in the postoperative period, including surgical emphysema in two patients and granulation tissue development at the anastomosis site in four patients. Eleven (27.5%) patients developed restenosis postoperatively, including two with complete stenosis and nine with partial stenosis. While 9 out of the 11 patients were successfully decannulated, 2 could not be decannulated despite the procedures performed (Table 3). Of the total 40 patients, 12 (30.0%) had a tracheostomy at the time of surgery, before grouping. Among them, eight were in the restenosis group and four in the non-restenosis group. All patients in the non-restenosis group were successfully decannulated. In the restenosis group, a total of eight whom already had a preoperative tracheostomy, and one who required it postoperatively. Of these 11 patients, 9 were eventually decannulated after repeated endoscopic interventions, while 2 continued to live with a tracheostomy. There was no statistically significant difference in TL, LNS, or TL/LNS ratio between the restenosis and non-restenosis groups. The TL/LNS ratio was 4.4 (IQR, 3.57–5.23) in the restenosis group versus 4.8 (IQR, 4–5.25) in the non-restenosis group (P=0.253) (Table 4). In the restenosis group, 8 (72.7%) patients required preoperative tracheotomy. Preoperative tracheostomy was present in 4 (13.8%) patients in the non-restenosis group. The intergroup difference was statistically significant among patients who required tracheotomy in the preoperative period (P=0.001). In the restenosis group, the degree of stenosis was as follows: 3 (27.3%) patients were classified as grade II, 6 (54.5%) as grade III, and 2 (18.2%) patients as grade IV; in the non-restenosis group (grade of stenosis before the surgery), these numbers were 16 (55.2%), 12 (41.4%), and 1 (3.4%), respectively. However, there was no statistically significant difference between the groups (P=0.154). In the restenosis group, 6 (54.5%) patients developed complications upon TRA, while no patients in the non-restenosis group developed complications, and this difference was statistically significant (P=0.001). In the restenosis group, 9 (81.8%) out of 11 patients could be decannulated, whereas all 29 patients in the non-restenosis group remained tracheostomy-free at final follow-up. This difference between the two groups was statistically significant (P=0.020) (Table 5).

Discussion

This study evaluated surgical outcomes of patients with post-intubation subglottic stenosis undergoing TRA, focusing on the predictive value of the TL/LNS ratio. Although the TL/LNS ratio was higher in patients without restenosis, the difference was not statistically significant. Decannulation rates were significantly higher in the non-restenosis group. These findings suggest that while TL/LNS may reflect surgical tension, it was not a reliable standalone predictor of restenosis. In contrast, a preoperative tracheotomy was strongly associated with increased restenosis risk and reduced decannulation success. Prolonged intubation has long been recognized as a leading cause of subglottic stenosis, with ischemic injury initiating within hours and fibrotic narrowing developing over weeks (11-14). Clinically significant narrowing is rare (15), yet when the tracheal diameter is reduced to 8 mm or less, exertional dyspnea and inspiratory stridor may occur (16,17). Treatment approaches vary depending on the severity and structure of the stenosis, ranging from endoscopic dilation to TRA (18,19). Granulation tissue at the anastomosis is a common complication, and tension at this site is a known risk factor for restenosis (20,21). Our findings align with these reports, particularly regarding the role of anastomotic tension and chin-to-chest sutures as a preventive measure (22-24). The use of absorbable sutures has been associated with reduced granulation tissue formation (25), supporting our choice of suture material.

Several studies have reported associations between restenosis and factors such as reoperation, diabetes, and the need for long resections or preoperative tracheotomy (26-28). Our findings reinforce the negative prognostic impact of preoperative tracheotomy. The inclusion of the stoma in the resected segment likely increases anastomotic tension and complication risk (28). Prior work has also demonstrated better outcomes with absorbable materials like PDS versus Prolene (28). Our results are consistent with complication and success rates reported by Donahue et al. (29), Bibas et al. (30), and Grillo et al. (13). In our study, complication, restenosis, and success rates were 15%, 27.5%, and 95%, respectively. While granulation tissue was the most common complication, it was not classified as restenosis. Reports by Abbasidezfouli et al. (31), Bibas et al. (30), and Wright et al. (26) confirm that tension, longer resections, infection, and comorbidities elevate the risk of anastomotic complications. The link between longer LNS and increased restenosis—possibly due to greater tension—has been demonstrated in previous research (32).

This study has several limitations. It was a retrospective single-center analysis, and all surgeries were performed by one surgeon, limiting generalizability. The small sample size—particularly in the restenosis subgroup—may have reduced statistical power. While Chi-squared tests were used, future analyses might benefit from Fisher’s Exact Test. Also, asymptomatic restenosis could have been underdiagnosed, as endoscopy was performed only in symptomatic cases.

Despite these limitations, our findings suggest that the TL/LNS ratio may offer preoperative insights into anastomotic tension. Larger, prospective multicenter studies are warranted to validate its prognostic utility and to define clinically meaningful cutoff points. Additionally, further exploration of patient-specific risk factors such as tracheotomy status, comorbidities, and anatomical proportions could support a more personalized approach to airway reconstruction. Since our study was not powered a priori to detect small TL/LNS differences, future trials should include power analyses to guide sampling.

Conclusions

Although the TL/LNS ratio was not found to be significantly associated with restenosis or surgical success in this cohort, preoperative tracheotomy was strongly correlated with increased restenosis rates and reduced decannulation success. These findings suggest that tracheotomy status may be an important factor in preoperative risk assessment. Larger prospective studies are needed to further evaluate the predictive value of the TL/LNS ratio in airway reconstruction.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://www.theajo.com/article/view/10.21037/ajo-24-75/rc

Data Sharing Statement: Available at https://www.theajo.com/article/view/10.21037/ajo-24-75/dss

Peer Review File: Available at https://www.theajo.com/article/view/10.21037/ajo-24-75/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://www.theajo.com/article/view/10.21037/ajo-24-75/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. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by Gaziantep University Clinical Research Ethics Committee (Approval Number: 376). Because of the retrospective nature of the research, the requirement for informed consent was waived.

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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