The Assessment of Subglottic and Cervical Tracheal Stenosis Using a Novel Point-of-Care Ultrasound Method: Measurement of Tracheal Radius Curvature.

Background and objective: The air way dimensions are important in the assessment, treatment and follow-up of patients with tracheal and subglottic stenosis (SGS). Non-invasive, non-radioactive methods to assess the degree of stenosis are needed. Point-of-care ultrasonography (POCUS) is an effective method for assessing the subglottic diameter and evaluating the abnormal airway. We explore the accuracy of POCUS measurement of the diameter of the subglottic and cervical trachea in patients with SGS and tracheal stenosis.

Methods: In this prospective, multi-centre study, volunteers and patients with SGS underwent POCUS, CT scanning, and flexible bronchoscopy. A radiologist measured the anteroposterior and transverse diameters of the trachea on the CT images and calculated the mean diameter (CT-mean). Air column width (ACW) and anterior tracheal wall thickness (ATWT) were obtained by POCUS. The diameter of the subglottic and cervical trachea was calculated using an equation based on the radius of curvature (CR).

Results: A total of 123 volunteers without tracheal disease and 103 patients with SGS participated in this study. We identified strong correlation between airway diameter measurement using US-CR and CT-mean (r = 0.96 and 0.95, p < 0.001, respectively) in both, the control group and in patients with SGS. The diameter of subglottic and cervical trachea assessed by US-CR is more accurate than the direct measurement of US-ACW. The intraobserver and interobserver repeatability of US-CR was excellent (all correlation coefficients > 0.95; p < 0.05).

Conclusion: The airway dimension measured using POCUS based on the radius of the curvature is a reliable tool for assessing the subglottic and cervical tracheal diameters.