Utility of Routine Spirometry Measures for Surveillance of Idiopathic Subglottic Stenosis

Abstract

aryngotracheal stenosis (LTS) is a broad set of diagnoses encompassing a heterogeneous group of fibroinflammatory conditions relating to narrowing of the glottis, supraglottis, subglottis, and trachea. 1 The subset of patients with isolated subglottic stenosis accounts for nearly half of LTS cases. 2 Idiopathic subglottic stenosis (iSGS) is a rare and slowly progressive condition with an unknown primary cause that results in fibrosis of the subglottic airway. It generally presents in otherwise healthy middle-aged white women with symptoms of dyspnea and stridor. [3][4][5][6] Current management of iSGS relies on a combination of surgical and adjuvant therapies based on physician preference and individual patient needs. Many patients can be treated suc-cessfully through endoscopic intervention, but owing to the recurrent nature of iSGS, greater than 85% of these patients required repeated intervention within 5 years. 7 Routine follow-up is necessary to monitor for recurrence of stenosis between interventions and as a means of quantifying response to treatment.The use of pulmonary function tests (PFTs) for the diagnosis of upper airway obstruction was first described in the 1960s, and several studies have since identified PFT values that can be used to follow gradual change in the degree of stenosis over time. [8][9][10][11][12][13][14] In 2013, Nouraei et al 9 established the expiratory disproportion index (EDI) as a highly sensitive and specific tool for differentiating LTS from other illnesses that pre-IMPORTANCE Because of the recurrent nature of idiopathic subglottic stenosis, routine follow-up is necessary for monitoring progression of stenosis. However, no easily accessible, standardized objective measure exists to monitor disease progression.OBJECTIVE To determine whether peak expiratory flow (PEF) can be used as a reliable and easily accessible biometric indicator of disease progression relative to other validated spirometry measures in patients with idiopathic subglottic stenosis. DESIGN, SETTING, AND PARTICIPANTSProspectively collected data on PEF, expiratory disproportion index (EDI), and total peak flow (TPF) from 42 women with idiopathic subglottic stenosis without comorbid lower airway or parenchymal lung disease who were treated at a single tertiary referral center between 2014 and 2018 were analyzed. The mean follow-up period was 18.2 months (range, 2-40 months). Ten patients initially screened were not included in the analysis owing to comorbid glottic or supraglottic stenosis or nonidiopathic etiology. MAIN OUTCOMES AND MEASURESMeasurements of PEF, EDI, and TPF were taken at preoperative visits and at all other visits. RESULTS Forty-two women (mean age, 51.5 years; 98% white [n = 41]) met the inclusion criteria. The area under the curve for PEF was 0.855 (95% CI, 0.784-0.926). The optimal cutoff value was 4.4 liters per second (264 L/min), with a sensitivity and specificity of 84.4% and 82.0%, respectively. The area under the curve for EDI was 0.853 (95% CI, 0.782-0.925). For TPF, this was 0.836 (...

Utility of Spirometry Values for Evaluating Tracheal Stenosis Patients Before and After Balloon Dilation

“…There were statistically significant improvements in most spirometry parameters after dilation, including FEV1, FEV1% F, PEF, FEF 25%, FEF 50%, MMEF, and EDI, with similar findings previously identified in patients with subglottic stenosis who underwent dilations. [11][12][13][14] We determined that the vertical length of the stenosis was significantly associated with the post-dilation values for FVC, FEV1, FEV1% F, FEF 50%, and MMEF (P ¼ .04, .003, <.001, .022, and .026, respectively). Expected average reference spirometry values could be predicted if the vertical length of stenosis was known, with a post-dilation FVC decrease of 0.24 L/s from the expected average FVC associated with an increase in the length of the stenosis by 1 unit.…”

“…10 Evidence has been reported to support the use of PEF, EDI, and other spirometric parameters for initial evaluations and for monitoring of suspected laryngotracheal stenosis cases, particularly those with subglottic stenosis. [10][11][12][13][14][15][16] Management strategies for tracheal stenosis include open techniques with laryngotracheal reconstructions, cricotracheal resections, tracheal resections with end-to-end anastomoses, and slide tracheoplasties; endoscopic techniques, including balloon dilations; and adjuvant therapies, including intralesional steroid injections and topical mitomycin C (MMC) applications, though the role of these wound-modifying agents remains controversial. 15,[17][18][19][20][21] This study aimed to evaluate the relationship between tracheal stenosis severity and pre-and post-balloon dilation spirometry parameters in order to assess for changes in spirometry values; to evaluate for the effects of stenosis-associated factors, including vertical length and grade of the stenosis, on postdilation spirometry values; and to clarify the role of woundmodifying agents in the management of these patients, using spirometry parameters as objective indicators of their effects.…”

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

“…However, Murgu et al 8 Recent studies have used various spirometry measurements, namely peak inspiratory flow (PIF), [11][12][13] peak expiratory flow (PEF), 3,13,14 peak expiratory flow percentage (PEF%), 15,16 and total peak flow (TPF) 10 in subglottic stenosis patients to assess disease progression and treatment response. By detecting early aerodynamic decline with PFT before severe clinical symptoms become apparent, laryngologists can start treating patients before the stenosis becomes critical and lifethreatening.…”

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

“…Notably, PIF was the most sensitive and specific for predicting timing of operative intervention. Carpenter et al 3 reviewed spirometry data on 42 women with iSGS to determine if PEF, EDI, and total peak flow were useful indicators for degree of obstruction and predicting operative intervention. The authors proposed a PEF cutoff value of 4.4 L per second based on their finding that 84.4% of patients who had surgery within 2 months had PEFs less than 4.4 L per second (264 L/minute).…”