An Attempt to Estimate Parameters Useful for Establishing a Normal Range for Peak Nasal Inspiratory Flow

Introduction: Measurement of peak nasal inspiratory flow (PNIF) has gained wide acceptance among clinicians due to its simplicity. Unfortunately, due to the lack of reference values, a single measurement does not provide any relevant information on the degree of nasal obstruction. We have therefore attempted to evaluate parameters that would be useful for establishing reference ranges for PNIF. Material and methods: The study was a part of an epidemiological study ECAP (Epidemiologia Chorób Alergicznych w Polsce [The Epidemiology of Allergic Diseases in Poland]). Inhabitants of Wrocław, Poland, aged 6–7, 13–14 and 20–45 years were randomly selected for the study. All the subjects had their medical history taken and their PNIF measured (using an In-Check inspiratory flow meter manufactured by Clement-Clark). Patients with a diagnosis of rhinitis and/or asthma were excluded from the study. In each subject, the highest of the five measurements (PNIF MAX) was included in the analysis. Results: A total of 221 healthy individuals were enrolled in the study. PNIF MAX differed significantly between females and males. A significant correlation was observed between height and PNIF MAX, although no such correlation was found between age and PNIF MAX. For this reason, in order to establish a reference range for PNIF, a regression equation that included sex and height was analysed. The following relationship was arrived at: PNIF MAX = −137.7 − 22.5x + 1.7y, where x is the sex (1 for females and 0 for males) and y is the height. The coefficient of determination (R2) for this relationship was 0.45, which means that the regression equation explains about 45% of the observed variability of PNIF MAX. Conclusions: We found that PNIF MAX correlated with sex and height and that it did not correlate with age. The difficulties in establishing normal ranges for PNIF are most likely due to the differences in nasal anatomy between the subjects.