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

Abstract

Objective The aim was to examine the correlations among the anatomic Cotton-Myer classification, pulmonary function tests (PFTs), and patient-perceived dyspnea or dysphonia in patients with subglottic stenosis and identify measurements accurately reflecting treatment effects. Study Design Prospective cohort study. Setting Tertiary referral center. Method Fifty-two adults receiving endoscopic treatment for isolated subglottic stenosis were consecutively included. Correlations were calculated among the preoperative Cotton-Myer scale, PFTs, the Dyspnea Index (DI), and the Voice Handicap Index. Receiver operating characteristic curves were determined for PFT, DI, and Voice Handicap Index pre- and postoperative measurements. Results The Cotton-Myer classification correlated weakly with peak expiratory flow ( r = −0.35, P = .012), expiratory disproportion index ( r = 0.32, P = .022), peak inspiratory flow ( r = −0.32, P = .022), and total peak flow ( r = −0.36, P = .01). The DI showed an excellent area under the curve (0.99, P < .001), and among PFTs, the expiratory disproportion index demonstrated the best area under the curve (0.89, P < .001), followed by total peak flow (0.88, P < .001), peak expiratory flow (0.87, P < .001), and peak inspiratory flow (0.84, P < .001). Patients treated endoscopically with balloon dilatation showed a 53% decrease in expiratory disproportion index (95% CI, 41%-66%; P < .001) and a 37% improvement in peak expiratory flow (95% CI, 31%-43%; P < .001). Conclusion Expiratory disproportion index or peak expiratory flow combined with DI was a feasible measurement for the monitoring of adult subglottic stenosis. The percentage deterioration of peak expiratory flow and increase in expiratory disproportion index correlated significantly with a proportional percentage increase in DI.

How can we identify subglottic stenosis in patients with suspected obstructive disease?

“…These groundbreaking works are further consolidated by our data, extending the evidence that EDI could differentiate particularly SGS from both asthma and COPD, the two diagnoses implicated in the diagnostic delay of this condition. Together with other studies discussing EDI’s role in monitoring the treatment effects of patients with subglottic stenosis, our study clearly spotlights the main benefit of extracting the EDI routinely from conventional spirometry [ 14 , 19 , 20 , 32 ].…”

“…Although DI showed a good AUC, it is practically nonfunctional in distinguishing SGS from nonstenosis considering that the cutoff value of 25 points is quite high, combined with a considerably lower sensitivity and specificity when compared to EDI. In our view, DI could further be used as a complementary measurement for assessing dyspnea in patients already diagnosed with upper airway obstruction, potentially affecting the decision-making and priority of a surgical intervention, as shown by other studies [ 17 – 19 ].…”

Balloon dilatation is superior to CO2 laser excision in the treatment of subglottic stenosis

“…Song et al [ 34 ] showed the poor interrater reliability of a visual estimation in Cotton–Myer grading among physicians and further discussed the difficulty in identifying cricoid cartilage when assessing stenosis length endoscopically. Moreover, neither of the two systems correlates with functional airway assessment with spirometry, as shown by several studies [ 35 – 37 ]. Since there is evidence that several measurements of pulmonary function could be used in the diagnosis and postoperative monitoring of patients with SGS [ 34 , 35 ], the lack of a preoperative functional evaluation with spirometry in our study population is considered another shortcoming of our study.…”

“…Moreover, neither of the two systems correlates with functional airway assessment with spirometry, as shown by several studies [ 35 – 37 ]. Since there is evidence that several measurements of pulmonary function could be used in the diagnosis and postoperative monitoring of patients with SGS [ 34 , 35 ], the lack of a preoperative functional evaluation with spirometry in our study population is considered another shortcoming of our study. Moreover, it would be interesting to quantify patient-experienced dyspnea using questionnaires specifically developed for upper airway obstruction [ 38 , 39 ].…”

Asymptomatic Subglottic Stenosis Discovered During Anesthesia Induction and Not Predicted by Preoperative Evaluation: A Case Report

“…No preoperative respiratory function tests were performed. SGS can be diagnosed based on extra-thoracic airway obstruction predicted by an expiratory disproportion index (the ratio of FEV1 to peak expiratory flow rate) > 0.5 [6]. In this case, a respiratory function test could have predicted the possibility of upper airway stenosis, and CT images could have helped in the early diagnosis of SGS, considering the patient history.…”