Should We Routinely Use Pulmonary Function Testing in the Management of Subglottic Stenosis?

[Balloon dilatation of subglottic stenoses, especially in granulomatosis with polyangiitis]

INTRODUCTION

Subglottic stenoses (SGS) are constrictions in the region below the vocal folds, that can pose a life-threatening problem for those affected. The aim of this research project was to identify the patient group for which the treatment of SGS by balloon dilatation can lead to long-term success.

METHODS

14 patients with SGS were examined (before and up to12 months after intervention) using pulmonary function tests, laryngoscopies and two questionnaires (Clinical Chronic Obstructive Pulmonary Disease Questionnaire), (modified Medical Research Council Dyspnoea Scale) regarding the respiratory situation. Additionally, the number of necessary interventions, the degree of stenosis (according to Myer Cotton and measured in millimeters) were documented.

RESULTS

Four patients who required only one intervention with the balloon showed better pre-interventional respiratory function and a higher subjective stress level. Lung function tests and evaluation of the questionnaires showed an improvement in the respiratory situation and state of health of all 14 patients after the initial intervention. The degree of stenosis measured in millimeters shows that patients with a stenosis diameter of less than 4 mm only required one intervention. All patients who received an intervention using a 12-mm-balloon had to be treated several times.

CONCLUSIONS

Patients with a high degree of stenosis and a tendency towards greater subjective stress and less objective restriction of the respiratory function appear to have a higher probability of long-term successful treatment with the balloon. Furthermore, the choice of balloon size seems to be an additional decisive factor for the success of an intervention.

Analysis of preoperative and postoperative blood gas indices and airflow dynamics with tracheal stenosis undergoing tracheal reconstruction

Prolonged ventilation remains the most common cause of tracheal stenosis. Tracheal reconstruction is the gold standard treatment in these cases. The success of surgery is based on results of the pulmonary function test (PFT) which relies on patients' performance and their cooperation. The objective of the study was to investigate the impact of tracheal reconstruction in cases of tracheal stenosis on blood gas indices as well as airflow indices and whether arterial blood gas (ABG) can be a better surrogate of adequacy of tracheal reconstruction. This was a retrospective observational study of 61 patients with tracheal stenosis between the ages of 21 and 65 years who underwent tracheal reconstruction. The preoperative and postoperative values of various blood gas indices like partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), and potential of hydrogen (pH) and airflow indices like forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) were evaluated and found that all the parameters showed significant improvement after tracheal reconstruction with P < 0.0001. Tracheal reconstruction resulted in improvement of oxygenation and airflow parameters which led to relief of symptoms. Hence, ABG can be used as a surrogate marker for denoting the success of the surgery.

Drug delivery systems for wound healing treatment of upper airway injury

INTRODUCTION

Endotracheal intubation is a common procedure to maintain an open airway with risks for traumatic injury. Pathological changes resulting from intubation can cause upper airway complications, including vocal fold scarring, laryngotracheal stenosis, and granulomas and present with symptoms such as dysphonia, dysphagia, and dyspnea. Current intubation-related laryngotracheal injury treatment approaches lack standardized guidelines, relying on individual clinician experience, and surgical and medical interventions have limitations and carry risks.

AREAS COVERED

The clinical and preclinical therapeutics for wound healing in the upper airway are described. This review discusses the current developments on local drug delivery systems in the upper airway utilizing particle-based delivery systems, including nanoparticles and microparticles, and bulk-based delivery systems, encompassing hydrogels and polymer-based approaches.

EXPERT OPINION

Complex laryngotracheal diseases pose challenges for effective treatment, struggling due to the intricate anatomy, limited access, and recurrence. Symptomatic management often requires invasive surgical procedures or medications that are unable to achieve lasting effects. Recent advances in nanotechnology and biocompatible materials provide potential solutions, enabling precise drug delivery, personalization, and extended treatment efficacy. Combining these technologies could lead to groundbreaking treatments for upper airways diseases, significantly improving patients' quality of life. Research and innovation in this field are crucial for further advancements.

The Subglottic Stenosis 6 Questionnaire: A Novel Quality-of-Life Survey Validated to Predict Need for Intervention in Patients With Idiopathic Subglottic Stenosis

BACKGROUND

Idiopathic subglottic stenosis (iSGS) is a recurrent, chronic disease defined by fibroinflammatory narrowing of the subglottic airway. A key challenge in treatment is monitoring disease progression, which may be debilitating and unpredictable in its timing.

RESEARCH QUESTION

Can the Subglottic Stenosis 6 (SGS-6) questionnaire be validated as a novel quality-of-life (QOL) instrument to monitor breathing, disease progression, and disease severity proactively in patients with iSGS?

STUDY DESIGN AND METHODS

Panel data from 51 patients with iSGS were collected from January 2012 through June 2022, representing 1,684 patient encounters including routine office visits and treatment encounters. Subjective QOL scores (including the novel SGS-6 and established RAND-36 and EuroQol Five Dimensions [EQ-5D] Visual Analog Scale) and objective pulmonary function test (PFT) results were collected at each visit. Subjective SGS-6 QOL scores were repeated within 1 week of initial reporting. Panel regression analyses were performed to assess the relationship between SGS-6 scores, PFT results, and a patient's need for intervention. Minimal clinically important differences (MCIDs) for SGS-6 and peak expiratory flow percentage (PEF%) were assessed using receiver operating characteristic (ROC) curve analysis and a patient's need for intervention as the external anchor.

RESULTS

Each one-point increase in SGS-6 score (of a maximum of 27) was associated with a 3.26% decrease in PEF%, a 1.93-point decrease in RAND-36 Physical Health composite score, a 1.27-point decrease in RAND-36 Mental Health composite score, and a 0.88-point decrease in EQ-5D Visual Analog Scale score. The intracorrelation coefficient for the SGS-6 composite score is 0.838 (95% CI, 0.770-0.888). Compared with patient baselines, SGS-6 scores were 4.66 points greater at the time of intervention with an MCID of 2.25 from a patient's baseline. The area under the ROC curve for SGS-6 and a patient's intervention point was 0.81.

INTERPRETATION

iSGS disease severity can be modeled using the SGS-6 questionnaire, offering physicians and patients a potentially new method of tracking disease progression and need for intervention remotely.

Can the Remote Use of a Peak Flow Meter Predict Severity of Subglottic Stenosis and Surgical Timing?

OBJECTIVE

We aimed to assess the relationship between patient-performed and patient-reported peak flow meter (PFM) measurements with pulmonary function testing (PFT) and Dyspnea Index (DI) scores as a tool for monitoring Subglottic stenosis (SGS) disease progression remotely.

METHODS

Thirty-five SGS patients were prospectively enrolled. Patients were given PFMs to report serial measurements from home. DI scores and PFT were recorded at serial clinic visits. Data were analyzed to determine the correlation between PFM measurements and PFT data. Pre-operative and post-operative PFM measurements, PFT, and DI scores were analyzed for patients who underwent operative intervention. Receiver operating characteristic (ROC) curves were created for PFM measurements, PFT data, and DI scores to predict the likelihood of surgery.

RESULTS

PFM measurements had a "strong" correlation with the peak expiratory flow rate (PEFR), r = 0.78. Means of PEFR, PIFR, EDI, PFM measurements, and DI scores all significantly improved after the operative intervention (p ≤ 0.05). The area under the curve for ROC curves for DI scores, PFM measurements, and EDI were highest in our cohort with values of 0.896, 0.823, and 0.806, respectively.

CONCLUSION

In our SGS cohort, PFM measurements correlate strongly with PEFR measurements. PFM measurements can adequately demonstrate disease progression and predict the need for surgery in this patient population. Together, DI scores and PFM measurements may be a useful tool to remotely follow patients with SGS and inform timing of in-person assessments.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:628-633, 2023.

Computational fluid dynamics model of laryngotracheal stenosis and correlation to pulmonary function measures

3D models of airway lumens were created from CT scans of 19 patients with laryngotracheal stenosis. Computational fluid dynamics (CFD) simulations were completed for each, and results were compared to measured peak inspiratory flow rate, grade of lumen constriction, and measures of airway geometry. Results demonstrate flow resistance and shear stress correlate with degree of lumen constriction and absolute cross-sectional area as well as flow rate. Flow recirculation depends on airway constriction but does not vary with flow rate. Resistance and wall shear stress did not correlate well with functional measures. Flow recirculation did differ between subjects with higher functional measures and subjects with lower functional measures. This analysis provides mathematical models to predict airway resistance, wall shear stress, and flow reversal according lumen constriction and inspiratory flow rate. It suggests aerodynamic factors such as flow recirculation play a role in differences in functional performance between patients with similar airway measures.

Pulmonary Function Tests May Better Predict Dyspnea-Severity in Patients with Subglottic Stenosis Compared to Clinician-Reported Stenosis

OBJECTIVE

Patients with subglottic stenosis (SGS) present with varied degree of breathing complaints. The dyspnea index (DI) is a 10-question patient-reported outcome measure designed to measure the severity of upper airway obstruction. We set out to determine whether pulmonary function tests or clinician-reported degree of stenosis best predicted DI scores.

METHODS

Thirty patients with SGS were retrospectively reviewed over a 6-year period. One visit from each patient was included. Data including peak expiratory flow rate (PEFR), body-mass index (BMI), clinician-reported degree of stenosis, and DI scores were reviewed. Multiple linear regression was performed to determine how degree of stenosis and PEFR % predicted the variation in DI score.

RESULTS

PEFR % better predicted DI scores compared to degree of stenosis (partial correlation -0.32 vs 0.17). After stepwise elimination, PEFR % remained in the regression and was significantly associated with DI scores (F[1, 29] = 9.38, P = .005). BMI did not demonstrate a linear relationship with DI scores and was not included in the regression (r = -.02). The PEFR % unstandardized coefficient was -0.25 (95% CI: -0.42 to -0.08, P = .005). The model predicts that a 4% increase in the PEFR % results in a 1-point decrease in the DI score (95% CI: -1.68 to -0.32).

CONCLUSION

This study suggests that pulmonary function tests may be a better in-office measure to substantiate the severity of symptoms in patients with SGS.

Modeling Recurrence in Idiopathic Subglottic Stenosis With Mobile Peak Expiratory Flow

OBJECTIVES/HYPOTHESIS

We sought to establish normative peak expiratory flow (PEF) data for patients with idiopathic subglottic stenosis (iSGS), evaluate whether immediate changes in PEF after a procedure predict long-term treatment response, and test if a decline in longitudinal PEF is associated with disease recurrence.

STUDY DESIGN

International, prospective, 3-year multicenter cohort study of 810 patients with untreated, newly diagnosed, or previously treated iSGS.

METHODS

iSGS patients consented and enrolled in the North American Airway Collaborative (NoAAC) iSGS¹⁰⁰⁰ cohort recorded PEF data on a mobile smartphone app. Cox regression tested the associations between the magnitude of postoperative PEF improvement and longitudinal 90-day PEF decline with the risk of disease recurrence.

RESULTS

Within the NoAAC iSGS¹⁰⁰⁰ cohort, 810 patients participated in a 3-year prospective study comparing surgical treatment efficacy and 385 had appropriate PEF measurements and follow-up data. Of those patients, 42% (161/385) required at least one operation during study follow-up. The mean PEF preceding operative intervention was 241 L/min (95% confidence interval [CI]: 120-380) corresponding to a predicted PEF of 52%. The mean increase in PEF following a procedure was 111 L/min (95% CI: 96-125 L/min). Interestingly, the magnitude of immediate PEF improvement was not predictive of disease recurrence (hazard ratio [HR] for 100 L/min increase = 0.90, 95% CI: 0.60-1.00). However, recurrence was associated with the magnitude of PEF decline over 90 days (30% vs. 10% decline, HR = 2.2, 95% CI: 1.5-3.0).

CONCLUSIONS

We provide normative PEF data on a large iSGS patient cohort. The degree of PEF improvement immediately after surgery was not associated with a longer procedure-free interval. However, a 30% decline in PEF over 90 days was associated with elevated risk of disease recurrence.

LEVEL OF EVIDENCE

2 Laryngoscope, 2021.

Quality of life after transoral CO2 laser posterior cordotomy with or without partial arytenoidectomy for bilateral adductor vocal cord paralysis

Objectives

Bilateral adductor vocal cord paralysis (BAVCP) is a rare and challenging condition whose main consequence is reduction of airway patency at the glottic level, often causing respiratory distress, while vocal function tends to remain almost normal. We investigated the effect of transoral glottal widening on quality of life and decannulation rates in patients affected by BAVCP.

Methods

We retrospectively evaluated patients affected by BAVCP and treated by transoral CO₂ posterior cordotomy with or without medial partial arytenoidectomy (PC ± MPA) at two referral centers. The primary outcome was change in quality of life, evaluated pre- and post-operatively by the ADVS, VHI-30, and EAT-10 questionnaires. Secondary outcomes were the need for retreatments and, for patients with tracheotomy, the time to decannulation.

Results

Thirty-three patients met selection criteria. The etiology was post-surgical in 27 cases (81.8%), idiopathic in 4 (12.1%), a trauma-related in 1 (6.0%), and to other causes in 1 (3.0%). In 22 cases (66.7%), PC was combined with MPA. A significant improvement in responses for the ADVS (p < .0001) and EAT-10 (p < .0001) was observed, whereas the VHI-30 score did not change significantly post-operatively. All nine patients with a tracheostomy were successfully decannulated within 18 months after the surgical procedure.

Conclusions

For patients affected by BAVCP, PC ± MPA by transoral CO₂ laser microsurgery is a safe, customizable and minimally invasive treatment that can guarantee an affordable balance between quality of life in terms of phonation and swallowing and acceptable airway patency.

Reliability of peak expiratory flow percentage compared to endoscopic grading in subglottic stenosis

OBJECTIVE

To determine the reliability of pulmonary function testing compared to endoscopic grading in the assessment of subglottic stenosis.

METHODS

Consecutively treated patients with subglottic stenosis at a tertiary care specialty hospital from 2009 to 2019 were identified. Two fellowship-trained laryngologists and two otolaryngologists blinded to clinical history reviewed laryngo tracheoscopic examinations and assessed the degree of stenosis using the Cotton-Myer grading system (% stenosis). Nine full flow-volume loops were performed at the time of each exam.

RESULTS

The endoscopic images of 45 subjects were graded for degree of stenosis and the spirometry data were analyzed. The kappa values for Cotton-Myer grade overall was 0.37, grade I was -0.103, grade II was 0.052, and grade III was 0.045. The overall intraclass correlation of the physician grading of estimated percent obstruction (% stenosis) was 0.712 (P < .01) whereas the overall intraclass correlation for PEF% was 0.96 (P < .01). Within each Cotton-Myer grade, the intraclass correlation for % stenosis was 0.45 (P = .02) for grade I, 0.06 (P = .30) for grade II, and 0.16 (P = .03) for grade III. The intraclass correlation for PEF% for grade I was 0.97 (P < .01), grade II was 0.92 (P < .01), and grade III was 0.96 (P < .01).

CONCLUSION

Cotton-Myer grading and estimating percent obstruction (% stenosis) for adult subglottic stenosis showed poor reliability as an assessment tool compared to the excellent intraclass correlation seen with pulmonary function tests within each Cotton-Myer grade subgroup. We recommend pulmonary function testing, specifically PEF% because it is a normalized value, for the assessment and management of subglottic stenosis.

LEVEL OF EVIDENCE

4.