Inter-rater and intra-rater reliability of the airway diameter measured by sonography

Introduction: Sonography has gained a broad field of applications in current anesthetic practice. During airway management, it could have an important role, because it allows real-time measurement of anatomical aspects and a functional evaluation with high safety profile. However, assessment of the reliability and precision of these measurements is critical if sonography is used as a clinical diagnostic tool. The aim of the study was to estimate inter-rater and intra-rater reliability of the airway diameter measured by sonography in heathy volunteers.
Methods: We conducted a cross-sectional study during 2015 on healthy adult volunteers. Using sonography, transverse internal diameter of subglottic space was measured twice by two blinded sonographers.
Results: Agreement was classified as very good for intra-rater measurements (ICC = 0.84) and good for the inter-rater measurements (ICC = 0.71). The 95% CI of agreement limits for the intra-rater measurements were inferior to those for the inter-rater measurements.
Conclusions: Ultrasound measurement is a reliable and precise method to measure the internal subglottic diameter of the airway. Ultimately, this method may provide clinicians valuable information regarding airway diameter in adults and may help to guide treatment options.