EVALUATION OF ACOUSTIC RHINOMETRY AND POSTERIOR RHINOMANOMETRY AS TOOLS FOR INHALATION CHALLENGE STUDIES

Objective measures of upper respiratory function are needed to underst and the effects of inhaled toxicants on the nasal passages. Acoustic r hinometry (AR) isa simple new technique that determines nasal volume b y measuring the cross-sectional area of the upper airway as a function of the distance along the nasal passage. This study compares acoustic rhinometry with the more traditional posterior rhinomanometry (NAR) a nd correlates these objective measures with the symptom of nasal conge stion. Healthy young adults (n = 29) were studied on 4 days, each sepa rated by at least I wk, in a climate-controlled environmental chamber for 6 h, with exposure to clean air or sidestream tobacco smoke (SS) ( 2 h, 1, 5, and 15 ppm CO). The coefficient of variation for single mea surements was 8-15% (AR) and 4% (NAR); for across-day measurements it was 15-25% (AR) and 13-75% (NAR); and for between days it was 19-27% A R and 17-21% (NAR). These coefficients were similar in subjects with a history of environmental tobacco smoke sensitivity (ETS-S) and those with no history oi ETS sensitivity (ETS-NS). At baseline, the percepti on of unilateral nasal congestion was significantly correlated with un ilateral nasal dimensions or nasal resistance; the symptom of baseline bilateral nasal congestion (estimated for both nasal passages simulta neously) correlated less well with objective measures of nasal patency . Under challenge conditions (SS at 1-15 ppm CO), there were typically significant correlations between changes in unilateral congestion and both unilateral rhinom-anometry and acoustic rhinometry, but correlat ions of bilateral congestion and measurable dimensions were much lower . ETS-S and ETS-NS subjects differed in correlations between bilateral subjective and objective measures: ETS-S subjects showed significant correlation between baseline congestion and NAR; in contrast, ETS-NS s ubjects showed significant correlation between baseline congestion and acoustic rhinometry. These results indicate that NAR and AR are compl ementary tests for use in inhalation challenge studies and have differ ent correlations with nasal congestion under baseline and challenge co nditions.