Phase variation in nasal airways resistance assessed by active anterior rhinomanometry.

Measurements of nasal airways resistance in normal subjects have shown a significant difference between values obtained in the two respiratory phases. Higher overall values are found during expiration in both the unprepared and decongested nose but these differences fail to maintain statistical significance after application of a decongestant. This indicates that the phase of respiration in which measurement is made must be routinely recorded especially when measurement is made without decongestant, and comparisons of data made only with recordings from equivalent parts of the nasal cycle.