Short-time variation in nasal mucosal swelling: a rhinostereometry study.
Rhinostereometry is an optical method to detect changes in nasal mucosal swelling. The method needs further specifications for standardised use. This study was performed in order to define the inter-individual variation, and to find whether the intra-individual short-time variation is greater, say, at the beginning of a sequence of registrations, as has been claimed. Bilateral registrations were made every 2 minutes for 30 minutes in healthy, non-smoking subjects, 15 women, and 15 men. The figures of each nasal cavity were evaluated separately. Compared with baseline, the range of changes was -2.9 to 3.0 mm, mean value 0.12 mm, with a standard deviation of 0.39 mm. No stabilisation of the variation was seen over time. There was no correlation with age or sex. The left and right nostrils changed degree of swelling independently in most cases, but in 8 cases there was a significant correlation between the nostrils. The time required for each pair of bilateral registrations varied between 15 and 90 s (mean 34 s, standard deviation 10 s). Data from the present study can be used for statistical power calculations in the planning of rhinostereometry studies using parallel groups.