Correspondence between anatomical locations and points on the area–distance curve of acoustic rhinometry in an artificial model of a 5-year-old Japanese child

Abstract

Determining the correspondence between points on the area–distance curve derived from acoustic rhinometry and the anatomical landmarks in the nasal and nasopharyngeal airway is important for the clinical evaluation of obstructive sleep apnea in children. In this study, area–distance curves derived from acoustic rhinometry (SER-2000; Rhino Metrics Co., Ltd., Denmark) were measured in a life-size, artificial, soft-silicon, upper-airway model of a healthy 5-year-old child (Koken Co., Ltd., Japan). We created obstacles in both the nasal cavity and nasopharynx with clay, simulating various grades of adenoid hypertorophy. On the area–distance curve, the anterior portion of the inferior turbinate corresponded to the region between the second notch and third peak, the posterior end of the nasal septum corresponded to the third peak, and the adenoid corresponded to the region from immediately after the third peak to 8 mm posterior to the fourth notch. The measured adenoidal volume matched the actual volume of the simulated adenoid; however, the measured airway volume of the nasopharynx according to acoustic rhinometry was far greater than the actual volume of the model. We conclude that the landmarks identified on the area–distance curve and the changes in adenoid volume measured with acoustic rhinometry have potential clinical application. However, acoustic rhinometry measurements of nasopharynx airway volume could be improved.