EVALUATION OF THE NASAL CAVITY BY ACOUSTIC RHINOMETRY IN NORMAL AND ALLERGIC SUBJECTS

With acoustic rhinometry, one can detect a difference in response to a topical decongestant between normal and allergic subjects at the mini mal cross-sectional area. The minimal cross-sectional area corresponds in most cases to the anterior end of the inferior turbinate or the fi rst valley, which occurs after the nose piece of the acoustic rhinomet er on the acoustic rhinometry graph. Allergic patients typically have an increase in nasal mucosal swelling, which leads to a decrease in th e nasal volume and area and, subsequently, to an increase in congestio n, In this study acoustic rhinometry was used to test normal and aller gic subjects before and after the application of a topical decongestan t (1% phenylephrine (Neo-Synephrine)). Symptoms were measured by a fiv e-point scale, Results showed that increasing symptom scores demonstra ted a trend toward being related to decreasing area as measured at the minimal cross-sectional area or nasal valve, The average total percen t change at the minimal cross-sectional area was calculated for both g roups and compared, The normal subjects had an average total percent a rea change at the minimal cross-sectional area of 15.6% +/- 14.8%, and the allergic subjects had a percent change of 24.6% +/- 20.8%. This r epresents a significant difference between the normal and allergic sub jects in response to the topical decongestant at the minimal cross-sec tional area (p = 0.04). However, the average total percent change was not significantly different between the two groups at the second and t hird valleys. At the second valley, the normal subjects had a percent change of 40% +/- 17.5%, and the allergic subjects had a percent chang e of 36% +/- 18.5%. At the third valley, the normal subjects had a per cent change of 35% +/- 15.4%, and the allergic subjects had a percent change of 32% +/- 20.6% (p = 0.4 and 0.5, respectively). The total are a was calculated by adding measurements from both right and left nasal cavities for each subject in an attempt to control the effect of the nasal cycle, Acoustic rhinometry makes it possible to detect a trend i n the relationship between either a decrease in area at the minimal cr oss-sectional area or a decrease in the total volume from 0 to 7 cm in to the nasal cavity and congestion. A statistically significant differ ence between normal and allergic subjects in their response to a topic al decongestant at the minimal cross-sectional area was detected by ac oustic rhinometry at the nasal valve.