NASAL RESPONSE TO INHALED HISTAMINE MEASURED BY ACOUSTIC RHINOMETRY IN INFANTS

Aerosolized histamine, delivered via a face mask, is commonly used to evaluate bronchial reponsiveness in infants. To investigate nasal response to inhaled histamine we have measured nasal passage geometry in 32 infants by the use of acoustic reflections. Satisfactory data were obtained from only 17 infants (12 males, 5 females, 6.6 +/- 4.4 months), because of awakening prior to completing the study in the remaining 15 infants. Acoustic rhinometry provided nasal cavity volume at 4 cm from the entrance of the nostril (VO4), the minimum cross-sectional area (A(min)), and the distance from the nostril to A(min) (D-min). Nasal geometry and lung function (maximum expiratory functional residual capacity [V-maxFRC] were measured before and immediately after a histamine challenge test using rapid thoratic compression. The histamine aerosols decreased both VO4 and A(min) significantly by a mean of 17% and 13%, respectively (P < 0.001). There was a small, but significant increase (mean = 0.19 cm) of D-min in the right side only, indicating a posterior dislocation of the narrowest site with swelling of the mucous membrane. In general, we found a dose-response relationship in grouped data, with a greater fall in VO4 with increasing dose of histamine, but there was no correlation between percent fall in VO4 and V-maxFRC. This pilot study suggests that histamine aerosol affects nasal cavity geometry and that of acoustic rhinometry in infants and children warrants further investigation. (C) 1994 Wiley-Liss, Inc.