Computer averaged nasal resistance.

Nasal resistances were measured before and after decongestion of the nasal mucosa by posterior rhinomanometry with a head-out body plethysmograph in 95 adults referred to our nasal airflow laboratory. These resistances were calculated by a time averaging method (1), the equation R = delta P/V at delta P 1.0 cm H2O (2) and R = delta P/V at the point of peak flow (3), and the results were compared. Correspondence between resistances from the time averaging method and those from the equation R = delta P/V at delta 1.0 cm H2O, the equation R = delta P/0.83V1.33 was obtained with statistical significance (P less than 0.001) and it is suggested that the value of resistance from the time averaging method represents transitional airflow. At resistances less than 3.5 cm H2O/L/sec, the time averaging method and the equation R = delta P/V at delta 1.0 cm H2O and at peak flow produced almost identical values. At resistances greater than 3.5 cm H2O/L/sec, the time averaging method produced values equivalent to those from the equation R = delta P/V at peak flow but values from the equation R = delta P/V at delta P 1.0 cm H2O different from the former two methods. The results suggest that nasal resistances from the time averaging method and the equation R = delta P/V at the point of peak flow are appropriate expression of nasal patency.