Acoustic rhinometry for evaluating the effectiveness of antihistaminics

Abstract

Acoustic rhinometry is a unique non-invasive technique for imaging and measuring the free cross-sectional area of the main nasal cavity. By so doing, reactions of the mucosa can be assessed at any selected site in the nose. The goal of this study was to define the optimal conditions for the utilization of acoustic rhinometry to determine the ability of an antihistamine to alter the effects of histamine in the mucous membrane of the nose. In a group of 30 healthy volunteers subjectively normal nasal breathing, and no history of allergy, rhinometry was performed to measure the cross-sectional area in the region of the head of the inferior nasal concha at 0.5, 10 and 15 min after histamine provocation. The volunteers subsequently received cetirizine as antihistamine. Four hours later, rhinometry was repeated after administration of histamine via the contralateral nostril. Findings showed that conchal dilatation measured 10 min after provocation was statistically less severe in 63.3% of the patients treated with cetirizine. Compared to pretreatment values, the ventilated cross-sectional area became 45.6% larger after administration antihistamine. These findings demonstrated that the nasal swelling measured 10 min after antihistamine administration was due to the effects of histamine and was not due to tactile or physical stimuli. The present studies showed that the new measurement technique is precise and reproducible. These results have also demonstrated that a acoustic rhinometry permits an objective assessment of drug efficacy while making it possible to avoid the errors observed in other variable regions of the nose, such as the nasal isthmus or nasopharynx as well as errors associated with subjective scoring systems.