Evaluation of the nasal response to histamine provocation with acoustic rhinometry

The objectives of this study were to evaluate the reproducibility of the na sal response to histamine with the acoustic rhinometer and to compare the r esponses in normal and rhinitic subjects. Our study comprised 10 normal and 10 rhinitic subjects. Each subject had six sessions of provocation: three with histamine phosphate at a concentration of 4 mg/mL and three with salin e phosphate provocation. Basal measurements of the nasal volumes were taken initially and then at 5-minute intervals for 90 minutes. All rhinometric m easurements were made bilaterally and in triplicate. The variation between the triplicate measurements (2% +/- 0.1% [95% CI]) and the variation betwee n the basal measurements (7.3% +/- 3.1% [95% CI]) were very low in both nor mal and rhinitic subjects. The comparison of the average congestive respons e of the normal subjects revealed that they responded steadily for at least 90 minutes to histamine and saline but that the response to histamine was significantly more important. There was also a low variability in the conge stive response between the subjects. The comparison of the average congesti ve response of the rhinitic subjects revealed that their responses were mor e dynamic, not steady, compared with those of the normal subjects. The resp onse was statistically significant only in the first few intervals. The com parison of the average congestive response to saline suggests that rhinitic subjects present a more important response than normal subjects. The compa rison of the average congestive response to histamine between rhinitic and normal subjects was not statistically different but was different in the sh ape of the response pattern. Acoustic rhinometry is a highly reproducible m ethod for measuring nasal volume in our provocation protocol. Histamine nas al provocation leads to a pattern of congestive response that is different in normal and rhinitic subjects. Histamine nasal provocation seems to be us eful in addition to the study of nasal hyperreactivity and, as such, could permit differentiation between rhinitic and nonrhinitic subjects.