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A 36-year-old female patient diagnosed with asthma at an external center was referred to us after her complaints did not improve, at which point, hoarseness was added to the complaints. Stridor was identified in a respiratory system examination. Tracheal stenosis was seen in a postero-anterior chest X-ray and a fixed airway obstruction in a respiratory function test, upon which, the patient was referred to the ear, nose and throat department. Subglottic stenosis was detected on a neck computerized tomography and a bronchoscopy evaluation. The etiology of subglottic stenosis was evaluated, collagen tissue markers were positive, and the patient was asked to undergo a rheumatology consultation. The patient was subsequently diagnosed with Sjögren syndrome based on a salivary gland biopsy result. This rare case is presented to underline the need to keep Sjögren syndrome in mind as an etiology of subglottic stenosis. [ABSTRACT FROM AUTHOR]

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COVID-19 pneumonia has increased tracheal complications because it increases the need for mechanical ventilation and causes mucosal damage in the airway mucosa. One of these complications is subglottic stenosis. Four patients who developed subglottic stenosis following the COVID-19 infection were examined and referred to the ear, nose, and throat clinic between June 2020 and June 2022. All the patients included in our study were male and 57,75± 14.38 years old on average. The median intubation time was 15.75±7.8 days. All patients received laser surgery with balloon dilatation treatment. The median number of laser surgery with balloon dilatation treatments was 2.25±0.95. We used laser surgery and balloon dilatation as an effective and safe treatment method in our patients to treat subglottic stenosis resulting from the damage caused by COVID-19 pneumonia in the airway mucosa. [ABSTRACT FROM AUTHOR]

Objectives: Our aim was to investigate the diagnostic challenges and management of relapsing polychondritis (RP) with airway involvement, highlighting the need for accurate diagnosis and effective intervention to prevent severe complications. Methods: In this retrospective study, medical records from January 2011 through June 2024 at a single tertiary-care institution were reviewed. This study was approved by the institutional review board. A total of 34 patients were diagnosed with RP, among whom 4 presented with significant airway complications. This study focused on these four patients, detailing their clinical presentations, diagnostic processes, and outcomes following various interventions. Results: All patients were initially misdiagnosed with asthma and later developed severe airway issues necessitating interventions such as tracheotomy and endotracheal intubation. Diagnostic imaging, microlaryngoscopy and bronchoscopy (MLB) were crucial for identifying subglottic stenosis and other airway alterations. Treatments included high-dose steroids, rituximab, and surgical interventions such as balloon dilation and tracheostomy. Only one patient could be decannulated; the other three remained dependent on tracheostomy and experienced significant complications due to emergency medical interventions. Conclusions: RP can manifest with nonspecific respiratory symptoms similar to asthma, which may delay correct diagnosis and appropriate treatment, leading to critical airway complications. The early, precise identification of RP, particularly with airway involvement, is vital. MLB and dynamic expiratory CT scans play significant roles in clinical diagnosis and management. A multidisciplinary approach involving otolaryngologists, rheumatologists, and pulmonologists is essential for optimizing patient outcomes and minimizing complications. [ABSTRACT FROM AUTHOR]

Introduction: Subglottic stenosis, manifested by granulation tissue hyperplasia, is challenging and requires multiple repeated treatments and stent maintenance at times. Corticosteroids prevent severe subglottic stenosis development owing to their antifibrotic and anti-inflammatory properties. Submucosal injection of glucocorticoids, a useful adjuvant therapeutic method, improves the mean interval between endoscopic procedures and reduces airway restenosis risks. Case Presentation: We report a rare case of a man with complex subglottic stenosis who underwent balloon dilatation combined with cryotherapy, stent placement, and adjuvant submucosal triamcinolone injection. The drug was injected efficiently and safely into the submucosal layer under percutaneous ultrasound guidance, and subglottic stenosis was well-controlled at a low cost. Conclusion: POCUS-guided medication injections may be a useful adjuvant medical therapy for subglottic stenosis. [ABSTRACT FROM AUTHOR]

Gastroesophageal reflux disease in children, which affects approximately 18% of infants, results from gastric contents flowing into the esophagus due to factors such as immature sphincter function. Regurgitation is normal and often resolves by age two; however, persistent gastroesophageal reflux disease can lead to otolaryngological lesions such as subglottic stenosis. PubMed, AIRE, Scholar, MEDLINE, Springer Nature Journal, and Scopus were searched from their inception to February 2024. Pediatric patients < 18 years diagnosed with subglottic stenosis and investigated for gastroesophageal reflux disease or related endoscopic findings were included. Studies not reporting relevant outcomes, duplicates, and non-English studies were excluded. Six studies conducted between 1990 and 2001 explored gastroesophageal reflux-associated otolaryngological issues among pediatrics. Among the 149 participants with subglottic stenosis, 53.47% had laryngopharyngeal reflux disease. Some studies used the Cotton–Myer classification to identify intubation and gastroesophageal reflux disease as primary causes. Younger age and difficulty with intubation were associated with subglottic stenosis severity. Early management of gastroesophageal reflux disease before surgical intervention improved outcomes and reduced endoscopic repair failure rates. A meta-analysis of risk ratios from three studies underscored the relationship's statistical significance, with an overall effect size of 0.03 (95%CI: 0.01 to 0.17) and a P-value <.0001. Heterogeneity analysis showed minimal variability across studies, supporting the observed association between gastroesophageal reflux disease and subglottic stenosis. The prevalence of gastroesophageal reflux disease in pediatric subglottic stenosis cases has been established, stressing the need for early diagnosis and treatment to minimize the necessity of surgery. [ABSTRACT FROM AUTHOR]

Objectives: The primary goal of this study was to systematically identify all relevant published articles on the use of primary endoscopic balloon dilation for the management of pediatric patients with subglottic stenosis, critically assess the technique's success, and determine which patients are the best candidates for the procedure. Methodology: This was a systematic review and meta-analysis that aimed to investigate the use and success rate of EBD for treating pediatric SGS. An electronic systematic literature search of three major databases, PubMed, EBSCO, and Web of Science&MEDLINE through Clarivate, was conducted to include the eligible articles. Results: A total of 14 unique studies were included in the final analysis, with 473 cases of pediatric SGS. The pooled success rate of EBD in treatment of pediatric SGS was 76% (k = 14 studies, 95% confidence interval [CI] = 0.65–0.86, P < 0.001, Q test for heterogeneity = 0.03, P <.001, I2 = 91%). Conclusions: We reported a high success rate of EBD in treating pediatric SGS. The reported complications were uncommon, although they can be serious and life threatening. The intensity of SGS may be related to the likelihood of therapy failure. [ABSTRACT FROM AUTHOR]

Objective: Endoscopic management of subglottic stenosis (SGS) includes a wide range of techniques. This 17‐year review compares treatment outcomes between carbon dioxide (CO2) laser and cold steel. Study Design: Retrospective chart review. Setting: Single tertiary care center. Methods: A chart review was performed for all patients undergoing endoscopic treatment of SGS at Cleveland Clinic between July 12, 2000 and September 1, 2017. Data collected included demographics, stenosis etiology, stenosis severity, comorbidities, treatment modality, and airway procedure history. The primary endpoint was repeated treatment‐free survival (RTFS) within 2 years using a Kaplan‐Meier analysis and Cox proportional hazard model. Results: A total of 139 patients (median [interquartile range] aged 48.7 [37.8, 57.0] years; 83.4% female) were included in the analysis, with etiologies including idiopathic (56.8%), granulomatosis with polyangiitis (25.2%), and intubation (16.5%). All patients underwent either cold steel (107 patients) or CO2 laser (32 patients) lysis of stenosis with concurrent dilation. RTFS within 2 years was 50.2% for CO2 laser and 31.9% for cold steel (hazard ratio [HR] and 95% confidence interval [CI]: 1.69, 0.96‐2.97, P =.07). In patients with no prior airway procedures, there was no difference in RTFS between laser and cold knife (P =.41). However, in patients with prior airway procedures, RTFS was significantly greater in the laser group, even after adjusting for age, smoking history, and stenosis etiology (50.0% vs 16.8%, adjusted HR and CI: 2.82, 1.14‐6.98, P =.025). Conclusion: Endoscopic lysis of SGS with CO2 laser should be considered in revision cases. [ABSTRACT FROM AUTHOR]

Purpose: An accurate diagnosis and proper treatment plan are required to restore an adequate patent airway in fibrotic subglottic stenosis (SGS). Currently, the definitive treatment entails single-stage balloon dilatation with steroid injections. The primary aim was to evaluate successful airway restoration and general quality of life in cases with SGS in northern Sweden using robust patient reported outcomes. Methods: All participants with need of surgical treatment due to SGS that had been referred to the department of otorhinolaryngology, University Hospital of Umeå from September 2020 to August 2023 was included. Exclusion criteria included malignant, extrathoracic or cartilaginous cause, age < 18 years, or incompetent to sign consent documents. We assessed the patient-reported outcome measures pre- as well as 3 months postoperatively. Results: Of the 40 cases fulfilling the eligibility criteria's, 33 cases completed the Dyspnea index (DI) and the short form health survey (SF-36) pre- as well as 3 months post-operatively. Receiver operating characteristics showed significant improvement in DI as well as in SF 36 scores post-operatively. Conclusions: Evaluation of balloon dilatation in SGS in this cohort follow-up analysis shows clear improvement in patient quality of life using robust PROM 3 months postoperatively, ensuring the use of a safe and well-tolerated procedure. [ABSTRACT FROM AUTHOR]

Subglottic stenosis is a condition causing narrowing of the trachea, which can occur rarely secondary to trauma, infection, tumors, inflammatory, and iatrogenic causes. In our case, the child developed subglottic stenosis postcardiac surgery after being mechanically ventilated in the postoperative period. The causes for subglottic stenosis may be some trauma in the presence of coagulation abnormalities in cyanotic heart diseases such as TOF, the ischemia to the subglottic tissue by reduced perfusion during cardiopulmonary bypass, and/or the trauma caused by crying and fighting of the child while being with the endotracheal tube. Anesthetic management of the surgery is challenging for the anesthesiologist due to the shared airway by the surgeon and the anesthesiologist. The inability to effectively ventilate the patient after induction of general anesthesia will result in catastrophic complications. Subglottic stenosis requires careful planning and execution along with proper communication between the team. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is a new, widespread virus pandemic that started in late 2019. It targets the respiratory system, especially the lungs and airways, through the spread of infected water droplets being inhaled through person-to-person transmission. Current treatments include oral antiviral pills like Paxlovid and mRNA vaccines, but these treatments have limitations in not reducing the occurrence of a common side effect of COVID-19. In this paper, we study the correlation of how SARS-CoV-2 (COVID-19) in intubated patients on ventilators can develop subglottic stenosis (SGS) during such treatments. When SARSCoV-2 patients are treated with these devices, their tubes can injure and possibly scar the airway epithelium, resulting in excessive scar tissue growth that blocks the airway, which is SGS. SGS arises when an injury in the airway stimulates rapid scar tissue growth to the point where the airway becomes too narrow and obstructed for breathing. It can also lead to the entire airway collapsing in severe cases. Even then, many current treatments for SGS, such as laryngotracheal reconstruction (LTR) and partial cricotracheal resection (CTR) surgeries, make the condition of the patients worse, especially with long-COVID patients with comorbidities potentially having a collapsed trachea. Thus, it is essential to find novel treatments to lower the risk of SGS in patients with such severe cases of COVID-19. Therefore, in this work, we discuss novel therapies to treat SGS cases that have been occurring from incidences of COVID-19 as a way to improve patient outcomes and save lives. [ABSTRACT FROM AUTHOR]

Objective: To report on a series of patients with cANCA/PR3‐positive, granulomatosis with polyangiitis (GPA)‐associated subglottic stenosis (SGS) and evaluate response to medical maintenance therapy with rituximab versus other immunosuppressants following initial endoscopic laser excision. Study Design: Retrospective chart review. Setting: Tertiary academic center. Methods: A retrospective chart review of patients with SGS and cANCA/PR3‐positive GPA who received immunosuppressive maintenance therapy following endoscopic laser excision at our institution from June 1989 to March 2020 was performed. Data pertaining to patient demographics, clinical features, medications, and endoscopic laser procedures were collected. Results: A total of 27 patients (15 women) with mean age (range) of 40 (19‐59) years and mean (range) follow‐up of 12.6 years (1.5‐28.6) were identified. Sixteen patients (60%) had limited GPA. Six patients (24%) had previously received local intervention with open surgery (n = 1, 4%) or endoscopic techniques (n = 5, 20%). All patients experienced symptom improvement following initial CO2 laser excision at our institution without any procedural complications or adverse events. Following initial laser excision, 15 patients (60%) were treated with rituximab and 10 patients (40%) were treated with nonrituximab immunosuppressive agents. Patients treated with rituximab were less likely to recur (P = 0.040). Limited GPA was associated with an increased incidence of recurrence (P = 0.031). Median time (years) to recurrence (range) was 3.2 (0.3‐19.3) and was not significantly associated with treatment or GPA subtype. Conclusion: Endoscopic CO2 laser excision is a safe and effective local intervention for GPA‐associated SGS. Medical maintenance therapy with rituximab reduces risk of recurrence following initial laser excision relative to treatment with non‐rituximab agents. [ABSTRACT FROM AUTHOR]

Objectives: The management of idiopathic subglottic stenosis (iSGS) poses a clinical challenge due to high recurrence rates following both endoscopic and open approaches, often leading to tracheostomy. The activation of abnormal T-cells and cytokine pathways has been linked to iSGS pathogenesis. Autologous adipose tissue centrifugation yields lipoaspirate, offering optimal anti-inflammatory effects and biocompatibility widely utilized in various medical settings. This report presents the first 3 cases employing endoscopic dilation (ED) in combination with local lipoaspirate injection to address recurrent iSGS. Methods: A prospective observational study was conducted, involving multidisciplinary evaluation by the Tracheal Team at the University of Modena. Patients meeting specific criteria were directed to undergo ED + lipoaspirate injection. Results: Three patients fulfilled the inclusion criteria. The mean number of prior endoscopic procedures performed was 8. Endoscopic examination revealed 90% stenosis in patient A, 60% stenosis in patient B, and 60% stenosis in patient C. All patients presented inflammatory tissue or incipient granulations at the stenotic site, with an average time of 6 months between previous procedures. After 15 months, none of the patients required further procedures, and endoscopic examination revealed a significant reduction or disappearance of inflammatory tissue with a stable airway lumen. Conclusions: The observed results are encouraging in terms of reducing local inflammation and halting stenosis progression, especially in cases of short-term relapsing iSGS. [ABSTRACT FROM AUTHOR]

OBJECTIVES Treatment options for benign subglottic stenosis include endoscopic techniques or open surgery. Although endoscopic treatment is less invasive, a considerable proportion of patients develop recurrent stenosis. Endoscopic pretreatments do not exclude patients from a later surgical repair; however, the impact of previous endoscopic treatment attempts on functional outcome after open surgery is unknown. METHODS All patients, who received a cricotracheal resection (CTR) between January 2017 and June 2023 at the Department of Thoracic Surgery, Medical University of Vienna, were included in this retrospective study. Patient characteristics, surgical variables and postoperative outcome including a detailed functional assessment were analysed. RESULTS A total of 65 patients received a CTR during the study period, of which 40 were treatment naïve and 25 had a median of 2 (range 1–9) endoscopic pretreatments. Less-invasive voice-sparing CTR or standard CTR were more often possible in treatment-naïve patients. In contrary, pretreated patients regularly required extended procedures (P  = 0.049). Three or more endoscopic treatments resulted in a significantly lower mean fundamental frequency (F0) after open repair (P  = 0.048). In addition, a trend towards smaller mean sound pressure levels, a higher voice handicap index, higher impairments in RBH scores (roughness, breathing and hoarseness) and a higher dysphagia severity index was found in pretreated patients. The respiratory outcome after surgery was comparable between both groups. CONCLUSIONS Multiple endoscopic pretreatments lead to worse voice quality after CTR. The impact of prior endoscopic treatment before surgical repair should be considered when discussing treatment options with patients suffering from subglottic stenosis. [ABSTRACT FROM AUTHOR]

Introduction: While most patients with iatrogenic tracheal stenosis (ITS) respond to endoscopic ablative procedures, approximately 15% experience a recalcitrant, recurring disease course that is resistant to conventional management. We aimed to explore genetic profiles of patients with recalcitrant ITS to understand underlying pathophysiology and identify novel therapeutic options. Methods: We collected 11 samples of granulation tissue from patients with ITS and performed RNA sequencing. We identified the top 10 most highly up- and down-regulated genes and cellular processes that these genes corresponded to. For the most highly dysregulated genes, we identified potential therapeutic options that favorably regulate their expression. Results: The dysregulations in gene expression corresponded to hyperkeratinization (upregulation of genes involved in keratin production and keratinocyte differentiation) and cellular proliferation (downregulation of cell cycle regulating and pro-apoptotic genes). Genes involved in retinoic acid (RA) metabolism and signaling were dysregulated in a pattern suggesting local cellular RA deficiency. Consequently, RA also emerged as the most promising potential therapeutic option for ITS, as it favorably regulated seven of the ten most highly dysregulated genes. Conclusion: This is the first study to characterize the role of hyperkeratinization and dysregulations in RA metabolism and signaling in the disease pathophysiology. Given the ability of RA to favorably regulate key genes involved in ITS, future studies must explore its efficacy as a potential therapeutic option for patients with recalcitrant ITS. [ABSTRACT FROM AUTHOR]

The current study trains, tests, and evaluates a deep learning algorithm to detect subglottic stenosis (SGS) on endoscopy. A retrospective review of patients undergoing microlaryngoscopy‐bronchoscopy was performed. A pretrained image classifier (Resnet50) was retrained and tested on 159 images of airways taken at the glottis, 106 normal‐sized airways, and 122 with SGS. Data augmentation was performed given the small sample size to prevent overfitting. Overall model accuracy was 73.3% (SD: 3.8). Precision and recall for stenosis were 77.3% (SD: 4.0) and 72.7 (SD: 4.0). F1 score for the detection of stenosis was 0.75 (SD: 0.04). Precision and recall for normal‐sized images were lower at 69% (SD: 4.35) and 74% (SD: 4), with an F1 score of 0.71 (SD: 0.04). This study demonstrates that an image classification algorithm can identify SGS on endoscopic images. Work is needed to improve diagnostic accuracy for eventual deployment of the algorithm into clinical care. [ABSTRACT FROM AUTHOR]

Acquired subglottic stenosis is a common complication of endotracheal intubation in infants. The risk increases in trisomy 21, patients undergoing bypass surgery, and having gastroesophageal reflux disease. Less invasive endoscopic balloon dilatation of subglottic stenosis has become a more common treatment modality compared to open surgical technique. Airway-related surgery needs meticulous preparation and good communication between the anesthetist, surgeon, and staff. More precaution and more effective preparation and communication are needed in neonatal airway surgery as it is physiologically easier to desaturate and develop hypoxemia compared to adults. We report a case of successful balloon dilation of Myer-Cotton class III subglottic stenosis with intermittent supraglottic jet ventilation and bag-mask ventilation in infants with trisomy 21.

Complete subglottic stenosis is often managed with surgical resection. However, involvement of the high subglottis can limit candidacy for open resection, and there are few treatment options for these patients. We refined an endoscopic approach that evolved into a tracheal rendezvous technique with T-tube placement as an alternative to open surgical resection. Here, we present our series, technique, and outcomes. A retrospective review was performed to identify patients who underwent endoscopic management of complete high subglottic stenosis at the University of California San Diego. The surgical technique was initially a two-step staged procedure and was subsequently revised to a single-stage procedure with stenosis ablation, dilation, and insertion of a T-tube, which was completed in one day. Patients were seen at regular follow-up intervals for reassessment. Five patients were identified with complete stenosis not amenable to surgical resection. The average age of the cohort was 44.8 years. The etiology of stenosis in all patients was related to prolonged intubation and tracheostomy, and the average length of stenosis was 19.6 mm. Stenosis resection was accomplished via laser ablation and balloon dilation, and the average T-tube length was 50.3 mm. All patients were discharged on postoperative day one. Two patients developed airway crusting within the T-tube and required emergency department visits. Decannulation was attempted in three patients, although failed in two. Tracheal rendezvous is a safe and effective procedure for patients with grade IV subglottic stenosis. This provides a feasible endoscopic alternative to patients who are not candidates for open surgical resection, ye are motivated to have phonatory capacity.

Abstract Introduction Coronavirus disease 2019 (COVID-19)-associated tracheal stenosis (COATS) may occur as a result of prolonged intubation during COVID-19 infection. We aimed to investigate patterns of gene expression in the tracheal granulation tissue of patients with COATS, leverage gene expression data to identify dysregulated cellular pathways and processes, and discuss potential therapeutic options based on the identified gene expression profiles. Methods Adult patients (age ≥ 18 years) presenting to clinics for management of severe, recalcitrant COATS were included in this study. RNA sequencing and differential gene expression analysis was performed with transcriptomic data for normal tracheal tissue being used as a control. The top ten most highly upregulated and downregulated genes were identified. For each of these pathologically dysregulated genes, we identified key cellular pathways and processes they are involved in using Gene Ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) applied via Database for Annotation, Visualization, and Integrated Discovery (DAVID). Results Two women, aged 36 years and 37 years, were included. The profile of dysregulated genes indicated a cellular response consistent with viral infection (CXCL11, PI15, CCL8, DEFB103A, IFI6, ACOD1, and DEFB4A) and hyperproliferation/hypergranulation (MMP3, CASP14 and HAS1), while downregulated pathways included retinol metabolism (ALDH1A2, RBP1, RBP4, CRABP1 and CRABP2). Conclusion Gene expression changes consistent with persistent viral infection and dysregulated retinol metabolism may promote tracheal hypergranulation and hyperproliferation leading to COATS. Given the presence of existing literature highlighting retinoic acid’s ability to favorably regulate these genes, improve cell-cell adhesion, and decrease overall disease severity in COVID-19, future studies must evaluate its utility for adjunctive management of COATS in animal models and clinical settings.

Introduction: Coronavirus disease 2019 (COVID-19)-associated tracheal stenosis (COATS) may occur as a result of prolonged intubation during COVID-19 infection. We aimed to investigate patterns of gene expression in the tracheal granulation tissue of patients with COATS, leverage gene expression data to identify dysregulated cellular pathways and processes, and discuss potential therapeutic options based on the identified gene expression profiles. Methods: Adult patients (age ≥ 18 years) presenting to clinics for management of severe, recalcitrant COATS were included in this study. RNA sequencing and differential gene expression analysis was performed with transcriptomic data for normal tracheal tissue being used as a control. The top ten most highly upregulated and downregulated genes were identified. For each of these pathologically dysregulated genes, we identified key cellular pathways and processes they are involved in using Gene Ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) applied via Database for Annotation, Visualization, and Integrated Discovery (DAVID). Results: Two women, aged 36 years and 37 years, were included. The profile of dysregulated genes indicated a cellular response consistent with viral infection (CXCL11, PI15, CCL8, DEFB103A, IFI6, ACOD1, and DEFB4A) and hyperproliferation/hypergranulation (MMP3, CASP14 and HAS1), while downregulated pathways included retinol metabolism (ALDH1A2, RBP1, RBP4, CRABP1 and CRABP2). Conclusion: Gene expression changes consistent with persistent viral infection and dysregulated retinol metabolism may promote tracheal hypergranulation and hyperproliferation leading to COATS. Given the presence of existing literature highlighting retinoic acid's ability to favorably regulate these genes, improve cell-cell adhesion, and decrease overall disease severity in COVID-19, future studies must evaluate its utility for adjunctive management of COATS in animal models and clinical settings. [ABSTRACT FROM AUTHOR]

OBJECTIVES Surgical treatment for airway stenosis necessitates personalized techniques based on the stenosis location and length, leading to favourable surgical outcomes. However, there is limited literature on functional outcomes following laryngotracheal surgery with an adequate number of patients. Methods We conducted a retrospective analysis of patients who underwent laryngotracheal surgery at the Department of Thoracic Surgery, Medical University of Vienna, from January 2017 to June 2021. The study included standardized functional assessments before and after surgery, encompassing spirometry, voice measurements, swallowing evaluation and subjective patient perception. RESULTS The study comprised 45 patients with an average age of 51.9 ± 15.9 years, of whom 89% were female, with idiopathic being the most common aetiology (67%). Procedures included standard cricotracheal resection in 11%, cricotracheal resection with dorsal mucosal flap in 49%, cricotracheal resection with dorsal mucosal flap and lateral cricoplasty in 24% and single-stage laryngotracheal reconstruction in 16%. There were no in-hospital mortalities or restenosis cases during the mean follow-up period of 20.8 ± 13.2 months. Swallowing function remained intact in all patients. Voice evaluations showed a decrease in fundamental vocal pitch [203 (81–290) Hz vs 150 (73–364) Hz, P  < 0.001] and dynamic voice range (23.5 ± 5.8 semitones vs 17.8 ± 6.7 semitones, P  < 0.001). However, no differences in voice volume were observed (60.0 ± 4.1 dB vs 60.2 ± 4.8 dB, P  = 0.788). The overall predicted voice profile changed from R0B0H0 to R1B0H1. CONCLUSIONS Laryngotracheal surgery proves effective in fully restoring breathing capacity while preserving vocal function. Even in cases of high-grade and complex airway stenosis necessitating laryngotracheal reconstruction, favourable functional outcomes can be achieved. [ABSTRACT FROM AUTHOR]

Endoscopy is the gold standard for characterizing pediatric airway disorders, however, it is limited for quantitative analysis due to lack of three‐dimensional (3D) vision and poor stereotactic depth perception. We utilize structure from motion (SfM) photogrammetry, to reconstruct 3D surfaces of pathologic and healthy pediatric larynges from monocular two‐dimensional (2D) endoscopy. Models of pediatric subglottic stenosis were 3D printed and airway endoscopies were simulated. 3D surfaces were successfully reconstructed from endoscopic videos of all models using an SfM analysis toolkit. Average subglottic surface error between SfM reconstructed surfaces and 3D printed models was 0.65 mm as measured by Modified Hausdorff Distance. Average volumetric similarity between SfM surfaces and printed models was 0.82 as measured by Jaccard Index. SfM can be used to accurately reconstruct 3D surface renderings of the larynx from 2D endoscopy video. This technique has immense potential for use in quantitative analysis of airway geometry and virtual surgical planning. [ABSTRACT FROM AUTHOR]

Introduction: Here we present the case of a newborn baby boy with severe plasminogen deficiency causing occlusive hydrocephalus and ligneous conjunctivitis. Case Presentation: Shortly after birth, the hydrocephalus was treated with a ventriculoperitoneal shunt implantation. However, the child had to be readmitted soon afterward because of shunt obstruction. Subglottic microtrauma caused by the necessary intubations then led to another life-threatening complication – subglottic stenosis with pseudomembrane formation. Microsurgical removal had to be performed to secure the airway. Initially, regular plasma transfusions achieved slightly elevated plasminogen activity levels and short-term improvement of the respiratory situation. However, shunt dysfunction reoccurred, and alternative treatment options were needed. Since therapy with plasminogen concentrate is already available in the USA with encouraging results, this treatment option was organized in hopes of equally good results for this patient. Fortunately, under short-term substitution with plasminogen concentrates, the implantation of a new ventriculoperitoneal shunt was successful, and respiratory problems resolved. Conclusion: Plasminogen concentrates are critically needed in Europe and other parts of the world to improve the care of and prevent complications among patients with plasminogen deficiency. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study is to assess the impact of two different ventilation techniques, jet ventilation and apneic anesthesia with intermittent ventilation (AAIV), on patient hemodynamics and operative time during endoscopic laryngotracheal stenosis surgery. Methods: Retrospective chart review of patients who underwent airway dilation for laryngotracheal stenosis by a single surgeon at a single institution from October 1, 2000 through January 2, 2020. Logistic regression, Mann–Whitney U tests and chi square analysis were used to determine statistical significance. Results: A total of 157 patients, 43 (27.4%) male and 114 (72.6%) female, and 605 total encounters were included for analysis. There were no significant differences in hemodynamic outcomes when comparing the AAIV and jet ventilation groups. Specifically, there was no significant difference in either peak end‐tidal CO2 or nadir O2 saturation between the AAIV and jet ventilation groups (p = 0.4016) and (p = 0.1357), respectively. The patients in the AAIV group had a significantly higher median BMI 32.93 (27.40–39.40) compared with 28.80 (24.1–32.65) (p = 0.0001). Although not necessarily clinically significant, patients with higher BMI had lower median O2 nadirs (97.8%) than non‐obese patients (99.2%) (p < 0.0001). The median total procedure time was equivalent when comparing the two ventilation techniques. Conclusion: AAIV is a safe method of ventilation for patients undergoing endoscopic laryngotracheal stenosis surgery with no significant differences in patient hemodynamics or procedure time when compared with jet ventilation. AAIV was the preferred method of ventilation for obese patients undergoing endoscopic laryngotracheal stenosis surgery. Level of Evidence: 3 Laryngoscope, 134:1343–1348, 2024 [ABSTRACT FROM AUTHOR]

Objective: There are several options for surgical management of subglottic stenosis, including endoscopic and open procedures. However, treatment algorithms, outcomes, and anesthetic management of subglottic stenosis during pregnancy are not well described. Data Sources: MEDLINE, EMBASE, and the Cochrane databases. Review Methods: A scoping review of management of subglottic stenosis during pregnancy was performed, and then reported in compliance with Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines. Inclusion criteria consisted of those with subglottic or tracheal stenosis aged greater than 18 years, those in whom management was performed during pregnancy, and those who reported delivery related outcomes. Results: After systematic review and detailed search of 330 identified articles, 15 articles met inclusion criteria and were included in the final analysis. All studies were case reports or case series (level 4 evidence). This study identified 27 patients. The median age was 29 and the median gestational age at intervention was 28 weeks. Left lateral positioning and fetal heart rate monitoring were used in nearly every case. The most common intervention performed was endoscopic balloon dilation. In many cases, jet ventilation or transnasal humidified rapid insufflation ventilatory exchange was satisfactory for maintenance of the airway. Three women ultimately required tracheostomy prior to labor and delivery. There was no fetal death or complications reported in these studies, and all but one woman proceeded to deliver at term. Conclusion: Endoscopic balloon dilation during pregnancy is safe and effective, resulting in optimized respiratory outcomes for the mother and safe delivery of the fetus. The third trimester appears to be safe for airway intervention. Laryngoscope, 134:1014–1022, 2024 [ABSTRACT FROM AUTHOR]

Abstract Objective The objective of our study was to document the feasibility of a novel endoscopic anterior cricoid split and rib grafting technique in a goat airway model. Study Design Feasibility pilot animal study. Setting Animal surgical laboratory at a tertiary hospital and research center. Methods Three Ardhi goats were utilized. After harvesting and shaping the rib graft, 2 sutures were inserted transversely into the graft. An endoscopic midline anterior cricoid split was performed and extended down through the first tracheal ring, followed by a balloon dilation of the site. Next, the 2 lower and upper graft suture ends were sequentially passed as endo‐extra laryngeal sutures and tied on the anterior neck skin. Laryngeal stent was utilized in 1 goat following graft placement. Results The surgery was successful in all included animals and bronchoscopy performed 7 days after surgery, revealed that the anterior graft was in good position. One goat developed surgical site infection leading to partial graft resorption. Conclusion This study demonstrated the feasibility of this novel procedure which is potentially useful for patients who are candidates for a single‐stage reconstruction. Future studies should investigate the safety and validity of this technique in a model with subglottic stenosis. Level of Evidence NA

Abstract Background Subglottic Stenosis (SGS), with increasing numbers of studies, is the most specific and common clinical type of Laryngotracheal Stenosis (LTS). There is rapid publication turnover with newer management introduced and expanding research field. To our knowledge, there is no bibliometric analysis of SGS yet. Methods In August 2022, we performed a thorough search in the Web of Science Core Collection database using the word “subglottic stenosis,” and “SGS.” The 580 articles were arranged based on correlation. The collected articles were then analyzed with an assessment of relevant factors. Meanwhile, we analyzed the top 100 most-cited articles on SGS. Results The frequency of publication on SGS has increased substantially over time. The USA has contributed the most articles (n = 301). Vanderbilt University published most of the articles among other institutions (n = 18). Laryngoscope topped the list of journals and has published 89 SGS-related articles. Research hotspots shift from surgical treatment to conservative management. Conclusions The SGS-related literature has grown rapidly in recent years. This study represents the first bibliometric analysis of scientific articles on SGS. Areas to improve in SGS research can be identified after this analysis of the most impactful articles on this topic.

Acquired subglottic stenosis is a common complication of endotracheal intubation in infants. The risk increases in trisomy 21, patients undergoing bypass surgery, and having gastroesophageal reflux disease. Less invasive endoscopic balloon dilatation of subglottic stenosis has become a more common treatment modality compared to open surgical technique. Airway-related surgery needs meticulous preparation and good communication between the anesthetist, surgeon, and staff. More precaution and more effective preparation and communication are needed in neonatal airway surgery as it is physiologically easier to desaturate and develop hypoxemia compared to adults. We report a case of successful balloon dilation of Myer-Cotton class III subglottic stenosis with intermittent supraglottic jet ventilation and bag-mask ventilation in infants with trisomy 21. [ABSTRACT FROM AUTHOR]

Objectives: Our aim was to investigate the diagnostic challenges and management of relapsing polychondritis (RP) with airway involvement, highlighting the need for accurate diagnosis and effective intervention to prevent severe complications. Methods: In this retrospective study, medical records from January 2011 through June 2024 at a single tertiary-care institution were reviewed. This study was approved by the institutional review board. A total of 34 patients were diagnosed with RP, among whom 4 presented with significant airway complications. This study focused on these four patients, detailing their clinical presentations, diagnostic processes, and outcomes following various interventions. Results: All patients were initially misdiagnosed with asthma and later developed severe airway issues necessitating interventions such as tracheotomy and endotracheal intubation. Diagnostic imaging, microlaryngoscopy and bronchoscopy (MLB) were crucial for identifying subglottic stenosis and other airway alterations. Treatments included high-dose steroids, rituximab, and surgical interventions such as balloon dilation and tracheostomy. Only one patient could be decannulated; the other three remained dependent on tracheostomy and experienced significant complications due to emergency medical interventions. Conclusions: RP can manifest with nonspecific respiratory symptoms similar to asthma, which may delay correct diagnosis and appropriate treatment, leading to critical airway complications. The early, precise identification of RP, particularly with airway involvement, is vital. MLB and dynamic expiratory CT scans play significant roles in clinical diagnosis and management. A multidisciplinary approach involving otolaryngologists, rheumatologists, and pulmonologists is essential for optimizing patient outcomes and minimizing complications.

Background: Subglottic Stenosis (SGS), with increasing numbers of studies, is the most specific and common clinical type of Laryngotracheal Stenosis (LTS). There is rapid publication turnover with newer management introduced and expanding research field. To our knowledge, there is no bibliometric analysis of SGS yet. Methods: In August 2022, we performed a thorough search in the Web of Science Core Collection database using the word "subglottic stenosis," and "SGS." The 580 articles were arranged based on correlation. The collected articles were then analyzed with an assessment of relevant factors. Meanwhile, we analyzed the top 100 most-cited articles on SGS. Results: The frequency of publication on SGS has increased substantially over time. The USA has contributed the most articles (n = 301). Vanderbilt University published most of the articles among other institutions (n = 18). Laryngoscope topped the list of journals and has published 89 SGS-related articles. Research hotspots shift from surgical treatment to conservative management. Conclusions: The SGS-related literature has grown rapidly in recent years. This study represents the first bibliometric analysis of scientific articles on SGS. Areas to improve in SGS research can be identified after this analysis of the most impactful articles on this topic. [ABSTRACT FROM AUTHOR]

Background: The management of subglottic stenosis (SGS) in granulomatosis patients with polyangiitis (GPA) has no clear guidelines. This systematic review aimed to identify different surgical techniques and evaluate the outcomes of applied procedures. Methods: An electronic search was performed using 3 major databases, CINAHL, PubMed, and Clinical key, to include relevant studies published from the databases from inception through January 2017. All primary studies reporting treatment of SGS in cases with GPA were included. Articles were excluded if not relevant to the research topic or if they were duplicates, review articles, editorials, short comments, unpublished data, conference abstracts, case reports, animal studies, or non-English studies. Results: Thirteen papers were included in our systematic review with a total of 267 cases for the qualitative review Endoscopic approaches showed favorable outcomes with the need to use multiple procedures to achieve remission. The open transcervical approach showed excellent results mainly after failure of other endoscopic techniques. Tracheostomy was necessary for severe respiratory obstruction symptoms. Medical treatment was essential for stabilizing the active disease and therefore may enhance the success rate postoperatively. Conclusion: Subglottic stenosis in patients with GPA requires a multidisciplinary approach to provide optimal management regarding disease activity, grade of stenosis, and severity of symptoms. [ABSTRACT FROM AUTHOR]

Objective: The Montgomery T-tube is a commonly used device initially designed as a temporary airway stent, but also used as a long-term airway solution for stenosis. For patients undergoing either endoscopic or open airway procedures, proper techniques for inserting these tubes are well documented. This review compiles the techniques used for insertion of the Montgomery T-tube stent. Methods: The NCBI Pubmed database was queried using the keywords: "stent," "Montgomery," "T-tube," "stenosis," "technique." A total of 33 papers were reviewed with 12 papers selected for the study. Papers were selected based on inclusion criteria of English language and whether the paper described a technique for insertion of a Montgomery T-tube into the airway. Papers were excluded if they did not describe the technique of insertion of Montgomery T-tubes or dealt with another aspect of T-tube management. Results: The 12 selected papers each described a different technique for insertion of a Montgomery T-tube stent. Though nearly all the selected studies described using a modified Seldinger technique for insertion of the T-tube, there were discrepancies and a wide array of different instruments used. The instrument and/or technique that was selected was often determined by the individual need of the patient. Several studies addressed the challenge of interrupting ventilation while inserting or exchanging a T-tube in the operating room. These studies described attaching the T-tube to the endotracheal tube to pass the T-tube into the airway while allowing for continuous ventilation. Yet other studies used optical forceps or rigid bronchoscopes to allow placement of the T-tube with direct visualization. Conclusion: There are many techniques used for the insertion of a Montgomery T-tube. Nearly all studies described using a modified Seldinger technique and all the studies agreed on the necessity of a team approach for placement of the Montgomery T-tube. [ABSTRACT FROM AUTHOR]

Objective: Severe subglottic stenosis develops as a response to intubation in 1% of the >200,000 neonatal intensive care unit infants per year and may require laryngotracheal reconstruction (LTR) with autologous hyaline cartilage. Although effective, LTR is limited by comorbidities, severity of stenosis, and graft integration. In children, there is a significant incidence of restenosis requiring revision surgery. Tissue engineering has been proposed to develop alterative grafting options to improve outcomes and eliminate donor‐site morbidity. Our objective is to engineer a decellularized, channel‐laden xenogeneic cartilage graft, that we deployed in a proof‐of‐concept, neonatal porcine LTR model. Methods: Meniscal porcine cartilage was freeze–thawed and washed with pepsin/elastase to decellularize and create microchannels. A 6 × 10‐mm decellularized cartilage graft was then implanted in 4 infant pigs in an anterior cricoid split. Airway patency and host response were monitored endoscopically until sacrifice at 12 weeks, when the construct phenotype, cricoid expansion, mechanics, and histomorphometry were evaluated. Results: The selective digestion of meniscal components yielded decellularized cartilage with cell‐size channels. After LTR with decellularized meniscus, neonatal pigs were monitored via periodic endoscopy observing re‐epithelization, integration, and neocartilage formation. At 12 weeks, the graft appeared integrated and exhibited airway expansion of 4 mm in micro‐CT and endoscopy. Micro‐CT revealed a larger lumen compared with age‐matched controls. Finally, histology showed significant neocartilage formation. Conclusion: Our neonatal porcine LTR model with a decellularized cartilage graft is a novel approach to tissue engineered pediatric LTR. This pilot study sets the stage for "off‐the‐shelf" graft procurement and future optimization of MEND for LTR. Level of Evidence: NA Laryngoscope, 134:807–814, 2024 [ABSTRACT FROM AUTHOR]

Objectives: To determine how initial postoperative airway endoscopy findings after stent removal predict successful decannulation in children undergoing double‐staged laryngotracheoplasty (dsLTP). Secondary objectives assessed timing of decannulation and number of endoscopic interventions needed after dsLTP. Methods: A case series with chart review included children who underwent dsLTP at a tertiary children's hospital between 2008 and 2021. Rates of decannulation, time to decannulation, and number of interventions after dsLTP were recorded for children with high‐ or low‐grade stenosis at the first bronchoscopy after stent removal. Results: Of the 65 children who were included, 88% had high‐grade stenosis and 98% had a preoperative tracheostomy. Successful decannulation happened in 74% of the children, and 44% of the children were decannulated within 12 months of surgery. For children with low‐grade stenosis at the first endoscopy after stent removal, 84% were successfully decannulated compared with 36% of the children with high‐grade stenosis (p = 0.001). After dsLTP, children with high‐grade stenosis required 7.5 interventions (SD: 3.3) compared with 4.0 interventions (SD: 3.0) for children with low‐grade stenosis (p < 0.001). Decannulated children with high‐grade stenosis necessitated more endoscopic procedures (7.0 vs. 3.7, p = 0.02). Time to decannulation was similar between children with high‐ and low‐grade early postoperative stenosis (21.9 vs. 17.8 months, p = 0.63). Conclusions: Higher grade stenosis identified on the first airway endoscopy after suprastomal stent removal is correlated with lower decannulation rates and more postoperative endoscopic interventions. Although time to decannulation was not impacted by early stenosis grade, surgeons might utilize these early airway findings to counsel families and prognosticate possible surgical success. Level of Evidence: 4 Laryngoscope, 134:963–967, 2024 [ABSTRACT FROM AUTHOR]

Stridor is an important symptom which should not be missed, especially in a child. The etiology could be multifactorial and will require a comprehensive investigation into its management. In this case, we discuss the clinician's dilemma in reaching a diagnosis due to various factors which were present in a single patient. This rare benign laryngeal squamous polyp was eventually diagnosed in an 11-week-old boy who presented with acute stridor. The diagnostic dilemma we discuss in this case was due to multiple maternal and fetal factors. He was a premature baby, intubated at birth, there was a maternal tuberculosis infection and he also had a cutaneous hemangioma which were all part of the diagnostic dilemma faced in his management which eventually led to an acquired subglottic stenosis. Our discussion will focus on how a thorough and proper evaluation is needed especially when there are many deceptive clues or signs present in a patient. [ABSTRACT FROM AUTHOR]

Objectives: Accurate and reproducible measurements of the pediatric airway are critical for diagnostic evaluation and management of subglottic and tracheal stenosis. The endoluminal functional lumen imaging probe (EndoFLIP) is a catheter‐based imaging probe which utilizes impedance planimetry to calculate luminal parameters, including cross‐sectional area and compliance. Herein, we demonstrate the feasibility of this system for multidimensional evaluation of the pediatric airway. Methods: 3D‐printed pediatric laryngotracheal models were created based on computed tomography scans, then artificially deformed to simulate both circumferential and posterior subglottic stenosis. Two observers made six measurements of the minimum cross‐sectional area (MCSA) and length of stenosis of each model with EndoFLIP. Agreement between observer measurements and model dimensions was evaluated using Lin's concordance correlation coefficient; inter‐observer reliability was assessed using intraclass correlation. Results: Four models were created: two without pathology (MCSA: 132.4, 44.3 mm2) and two with subglottic stenosis (MCSA: 28.7, 59.7 mm2, stenotic length 27.8, 24.4 mm). Observer measurements of MCSA and length of stenosis demonstrated high concordance with the models (r = 0.99, 0.95, p < 0.001) with a mean error of 4.5% and 18.2% respectively. There was a low coefficient of variation (0.6%–2.8%) for measurements, indicating high precision. Interrater reliability was high for both MCSA and stenotic length (ICC: 0.99, 0.98). Conclusions: The EndoFLIP system allows for accurate and reproducible measurements of cross‐sectional area and stenotic length in pediatric airway models. This method may provide further advantages in the evaluation of airway distensibility, as well as measurements of asymmetric airway pathology. Level of Evidence: NA Laryngoscope, 134:108–112, 2024 [ABSTRACT FROM AUTHOR]

Objectives: 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. Methods: 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. Results: 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). Conclusion: 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. Level of Evidence: 3 Laryngoscope, 134:257–263, 2024 [ABSTRACT FROM AUTHOR]

Background: The tracheo-innominate fistula is a rare and potentially life-threatening entity that occurs in approximately less than 1% of patients after a tracheostomy. It occurs when the anterior wall of the trachea erodes and comes into contact with the posterior wall of the innominate artery or brachiocephalic trunk due to excessive pressure from the hyperinflation of the cuff over the mucosa, creating a fistulous tract. Clinically, it manifests as massive tracheal bleeding that puts the patient's life at imminent risk. Case presentation: We present the case of a 60-year-old Latin American male patient with a history of SARS CoV-2 pneumonia approximately 4 months earlier, who required prolonged orotracheal intubation and tracheostomy due to subglottic stenosis, which required tracheal dilations. The patient was admitted to the emergency department due to hemoptysis associated with hemodynamic instability and later on presented with massive tracheal bleeding. The chest-CT angiography evidenced a tracheo-innominate fistula that required surgical management. A concomitant Mycobacterium Tuberculosis infection was also diagnosed during his hospitalization. Conclusions: There are currently many gaps in our knowledge about the tracheo-innominate fistula, mainly in terms of its incidence following the SARS-CoV-2 pandemic, as well as the role that concomitant infections and their treatments, such as tuberculosis, play in the development of these events. During the pandemic, the cases of intubated patients and patients with tracheostomies increased, giving way to new and unexpected complications, we have yet to study in depth. [ABSTRACT FROM AUTHOR]

Abstract. – OBJECTIVE: Subglottic stenosis (SGS) is an unusual clinical condition of mucosal wounding, compromising the extra-thoracic part of the tracheal airway below the vocal folds. The diagnosis of SGS is established with a detailed clinical examination and a direct endoscopic examination, and the role of spirometry is also often acknowledged. This study aimed to investigate the impact of SGS on lung functions before and after the balloon dilation procedure. PATIENTS AND METHODS: The respiratory functions were performed in the Department of Clinical Physiology and the Department of Otolaryngology College of Medicine, King Saud University, Riyadh, Saudi Arabia. In this study, 50 patients with SGS were referred from the Department of Otolaryngology, and lung functions before and after the balloon dilation procedure among patients with SGS were performed using an electronic spirometer. RESULTS: The results revealed that the mean values for lung function test parameters VC (p=0.01), FVC (p=0.01), FEV1 (p=0.004), FEV1 / FVC Ratio (p=0.01), PEFR (p=0.01), FEF-25% (p=0.01), FEF-50% (p=0.01), and FEF-75%, (p=0.01) were significantly improved in both male and female patients with SGS on one month after the balloon dilation procedure. CONCLUSIONS: It is concluded that the lung function test parameters were increased after the balloon dilation procedure among patients with SGS. The findings showed the impact of SGS on lung function test parameters. Spirometry is a valuable test in patients with SGS and is an appropriate marker to reveal post-airway outcomes. Physicians must suggest lung function tests in patients with SGS before and after the balloon dilation procedure. [ABSTRACT FROM AUTHOR]

Subglottic stenosis (SGS) is a rare yet potentially life-threatening condition that requires prompt identification and treatment. One of the primary symptoms of SGS is a respiratory sound that is tonal. To better understand the effect of SGS on expiratory sound, we used direct noise calculation to simulate sound production in a simplified axisymmetric configuration that included the trachea, the vocal folds, the supraglottal tract, and an open environmental space. This study focused on flow-sustained tones and explored the impact of various parameters, such as the SGS severity, the SGS distance, the flowrate, and the glottal opening size. It was found that the sound pressure level (SPL) of the expiratory sound increased with flowrate. SGS had little effect on the sound until its severity approached 75% and SPL increased rapidly as the severity approached 100%. The results also revealed that the tonal components of the sound predominantly came from hole tones and tract harmonics and their coupling. The spectra of the sound were greatly influenced by constricting the glottis, which suggests that respiratory tasks that involve maneuvers to change the glottal opening size could be useful in gathering more information on respiratory sound to aid in the diagnosis of subglottic stenosis. [ABSTRACT FROM AUTHOR]