Repeatability of peak nasal inspiratory flow rate (PNIF) measurements and its change after administration of 0.05% oxymetazoline

BACKGROUND: Measurement of PNIF is a cheap and easily performed method to assess nasal patency. However, the assessment of repeatability of this parameter as well as the threshold value of change which can be considered significant have not been established yet. The aim of this study was to assess the repeatability of PNIF measurements and its change after the administration of 0.05% oxymetazoline. METHODS: Repeated measurements of PNIF (In-Check9s Clement-Clark) were performed in 333 (174 women) healthy volunteers. Subjects were divided into three age groups (6-7, 13-14 and 20-45 years). Each subject carried out 5 measurements. PNIF was retaken 30 minutes after inhaling 0.05% oxymetazoline in 294 subjects. The variability of the PNIF was assessed using the coefficient of variation (CV=standard deviation x 100% / mean). RESULTS: The first four PNIF measurements significantly differed from each other. There was no statistically significant difference only between the fifth and fourth measurement (p=0,19). PNIF repeatability was found at the acceptable level;. the median value of CV was 15.5% (0-66), and it did not vary significantly between age groups. Statistically significant increas in PNIF value by 14.3% (-45, 157%) was observed the after administration of 0.05% oxymetazoline (p=0,000000) CONCLUSIONS: 1.Only the PNIF value from the 4th and 5th sample did not differ significantly, thus at least 3 measurremnts are needed. 2.The PNIF is satisfactorily characterized by a relatively low coefficient of variation (15%). 3. The administration of oxymetazoline 0.05% causes an increase in PNIF by approximately 14% from the baseline value.