Normal range for nasal partitioning of airflow determined by nasal spirometry in 100 healthy subjects

Background: Nasal spirometry has been used previously to monitor the nasal cycle. Asymmetry of nasal airflow is expressed as a nasal partitioning ratio (NPR) that ranges from - 1 (left nasal cavity obstruction) to + 1 (right nasal cavity obstruction) with 0 indicating symmetry of airflow. This study investigated the normal range of NPR in the decongested nose as a means of assessing the degree of nasal septal deviation. Methods: NPR was measured in 100 healthy volunteers using a portable spirometer. Results: Mean NPR before decongestion was - 0.1 +/- 0.32 SD (range, -0.84-0.75), and after decongestion mean NPR was -0.02 +/- 0.16 SD (range, -0.46-0.51). Male NPR ranged from -0.46 to 0.51 (mean, -0.1 +/- 0.22) whereas female NPR was from -0.21 to 0.37 (mean, -0.03 +/- 0.1; P < 0.001). There was a significant correlation between the clinicians assessment of the degree of septal deviation and NPR, r(s) = 0.69 (p < 0.01). The 95% reference range for NPR in this normal population was found to be between +0.30 and -0.34. Conclusion: A normal range of NPR may prove useful in assessing patients complaining of nasal obstruction. A case may be made that patients on the waiting list that fall within the normal range of NPR are unlikely to benefit from septal surgery because their nasal passages are not greatly asymmetrical.