Investigation of Repeatability of Peak Nasal Inspiratory Flow Rate Measurements Under Baseline Conditions and After Administration of 0.05% Oxymetazoline

Objectives Peak nasal inspiratory flow (PNIF) measurement is an inexpensive and user-friendly method to assess nasal patency. However, the repeatability of PNIF measurements, as well as the threshold value of a change in PNIF, which can be considered significant remain unclear. This study aims to investigate the repeatability of PNIF measurements and the change in PNIF after the administration of 0.05% oxymetazoline. Methods Repeated measurements of PNIF (Clement Clarke In-Check nasal inspiratory flow meter; Clement Clarke International, Ltd, Harlow, Essex, UK) were obtained in 333 healthy volunteers (174 women). Based on age, participants were categorized into three groups (6-7 years, 13-14 years, and 20-45 years). We obtained five measurements in each participant. PNIF was remeasured in 294 subjects 30 min after administration of 0.05% oxymetazoline. The variability in PNIF measurements was assessed using the coefficient of variation (CV = standard deviation x 100%/mean). Results The first four PNIF measurements significantly differed from each other. The difference in PNIF measurements ceased to be statistically significant only between the fourth and fifth measurements (p = 0.19). PNIF repeatability was acceptable; the median CV was 15.5% (0-66), which did not significantly differ between age groups. The administration of 0.05% oxymetazoline led to a statistically significant increase in the PNIF value by 14.3% (-45, 157%) (p = 0.000000). Conclusions 1. No statistically significant difference was observed in PNIF values only between the fourth and fifth measurements; therefore, at least three measurements are essential to draw meaningful conclusions. 2. PNIF measurements were satisfactorily characterized by a relatively low CV (15%). 3. The administration of 0.05% oxymetazoline led to an increase in PNIF by approximately 14% over the baseline value.