Improving the reproducibility of acoustic rhinometry in the assessment of nasal function.

Acoustic rhinometry readings are very position dependent, and it was hypothesized that this accounts for its relative lack of reproducibility on a day-to-day basis. Multiple readings on each visit were taken to investigate their impact, if any, on improving the day-to-day reproducibility of the method. Measurements of the minimal cross-sectional area of the nose as measured by acoustic rhinometry were studied in 10 subjects following nasal decongestion. For each individual, acoustic rhinometry was performed ten times. The ten recordings were repeated again, in an identical manner on a separate day. The subjects were repositioned and the nasal probes reinserted between each measurement. The mean coefficient of variation for minimal cross-sectional area readings in all 10 subjects was calculated as 9.92%. This is comparable to the day-to-day variability of acoustic rhinometry as measured by other workers and thus supports the hypothesis that the high measurement error of the device (rhinometer) is a function of positional variation during data acquisition. We were able to demonstrate a minimal gain in intervisit reproducibility by doing multiple recordings per person, with a plateau effect of reproducibility after 7 repeat readings.