Comparison of sequential anterior and posterior rhinomanometry.

This study was conducted to test the validity in adult subjects of the commonly used technique of summing anterior nasal measurements to describe the patency of the total nose. We measured the total nasal conductance in 36 nonallergic, nonsmoking subjects by use of posterior rhinomanometry (PRM) and compared the results with sequential summed unilateral conductances in the same subjects based on anterior rhinomanometry (ARM). Linear regression of the relationship between the two measures demonstrated significant differences. Variation between these two measures is composed of two parts: random time variation and a component attributable to the difference between methods. Random time variation was estimated from five serial posterior nasal conductances in nine of the subjects in a second experiment. We observed significantly greater variations between ARM and PRM than between PRM measures separated by similar time intervals (F 36.36 = 2.30, p less than 0.01). We conclude that PRM is significantly more accurate than summed ARM when the goal is to quantitate precisely the patency of the nose as a whole at a given instant in time, and yet summed ARM measurements may be acceptable in clinical studies wherein large changes in nasal patency occur.