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

Abstract

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.

An Updated Review of Subglottic Stenosis: Etiology, Evaluation, and Management

“…One study found endoscopic grading of stenosis may have poor reliability compared to PFTs, and another found no correlation between grading of stenosis and PFTs [66,67]. However, peak expiratory flow has been shown to be a simple measurement to monitor iSGS progression with a sensitivity and specificity of 84.4% and 82.0%, respectively [68].…”

Monitoring Adult Subglottic Stenosis With Spirometry and Dyspnea Index: A Novel Approach

“…14 Lately, PEF%-as the patient's measured PEF divided by the predicted PEF for someone of the same age, height, and sexwas proposed as a standardized spirometry measurement to describe disease severity in patients with subglottic stenosis. 18,20 Furthermore, Naunheim et al sought to identify associations between PEF% and specific questions from a range of quality of life instruments. 20 According to the American Thoracic Society, breathlessness should be measured regardless of its cause, to be assessed properly.…”

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

“…At least 6 months after surgical treatment objective ventilatory function was evaluated on the basis of the flow-volume loop obtained by a spirometer. Pulmonary function test (PFT) was performed on all patients measuring the postoperative peak expiratory flow (PEF), a well-established objective parameter to evaluate the extent of residual airway obstruction [21][22][23]. The decannulation rate was a secondary outcome, measurable for the cohort of patients with a tracheostomy at the time of the surgical procedure (n = 12, 30%).…”