[Acoustic rhinometry: measuring the early and late phase of allergic immediate reaction in allergic rhinitis].

Acoustic rhinometry is a method to analyse nasal airway geometry. Almost every antigen-induced allergic reaction in the nasal cavity leads to morphologic changes known as nasal obstruction. Therefore a study in 8 patients suffering from allergic rhinitis was conducted. Patients were challenged with 1,000 Biological Units (BU) of grass pollen or D. pteronyssinus extract in one nostril. Acoustic rhinometry (AR) was performed before and 10, 20, 30, 45 and 60 minutes and then 2 to 8 hours after allergen exposure. 4 of the patients developed a late phase reaction. Changes were seen in the minimal cross-sectional area (MCA) and even better in a newly induced volume parameter called volume A (V-A). Volume A is calculated by integration of the distance/area graph surrounding the anterior part of the lower turbinate. Thus we can get information on more than one point of a graph in the important region of the anterior nose. Early phase reaction leads to a decrease in both MCA and V-A from 30% to 10% of the baseline value whereas late phase reaction gives only a third of this effect. The contralateral V-A and MCA are only slightly affected in the early phase, but there is an almost symmetric reaction of both sides in the late phase reaction. All changes were more pronounced in V-A compared to MCA. Therefore we propose to add V-A to MCA in describing the results of AR. Acoustic rhinometry is a suitable method for measuring local changes following nasal allergen challenge.