Accuracy of measurement of acoustic rhinometry applied to small experimental animals

Nasal obstruction is one of the major symptoms of allergic rhinitis. In the study of the mechanism of nasal obstruction, experiments on animal are use ful. In adult humans, acoustic rhinometry has been used to evaluate nasal o bstruction by determining nasal cavity dimensions in terms of cross-section al areas as a function of the distance from the nostril. We modified the eq uipment used on humans to assess dimensions of nasal airway geometry of sma ll experimental animals. The purpose of this study was to investigate the a ccuracy of measurement of the modified acoustic rhinometry applied to small experimental animals using nasal cavity models and guinea pigs. Measuremen t of the nasal cavity models (made of cylindrical silicone tubes) showed th at the acoustic rhinometry estimated 85.5% of actual area and 79.0% of actu al volume. In guinea pigs, nasal cavity volume determined by the acoustic r hinometry was 73.3 +/- 20.0% of actual volume. The actual volume was estima ted by impression material instilled into the nasal cavity of the animals ( IM volume), and volume determined by acoustic rhinometry significantly corr elated with IM volume. Furthermore, there was a significant negative correl ation between the volume and nasal airway resistance in guinea pigs. Measur ements of the nasal airway resistance is the method frequently used in the evaluation of the nasal obstruction in guinea pigs. These results suggest t hat acoustic rhinometry is useful in evaluating nasal obstruction in small experimental animals.