Nasal resistance--a reliable assessment of nasal patency?

This study was undertaken to determine the distribution of nasal resistance in a healthy white population. One hundred subjects without nasal complaints were selected for the investigation. The test subjects were divided into two groups on the basis of anterior rhinoscopy. Group 1 included 60 subjects with rhinoscopically normal noses. Group 2 included 40 subjects with rhinoscopically abnormal noses. The pressure-flow data were recorded via active anterior mask rhinomanometry. The analogue pressure and flow signals were sampled and digitized by a computer system according to the time averaging method. Nasal resistance was calculated according to the recommendations of the International Committee on Standardization of Rhinomanometry. The normality of unilateral nasal resistance data distributions was assessed by the Kolmogorov-Smirnov Goodness of Fit Test at inspiratory and expiratory corresponding pressures of 50 Pa, 75 Pa, 100 Pa, and 150 Pa. The distributions of the calculated total resistance data were estimated at inspiratory and expiratory reference pressures of 75 Pa and 100 Pa. The data distributions of the two groups were compared using the Mann-Whitney U-test. Distributions for unilateral resistance were frequently found to deviate from normality. The distributions of total nasal resistance data never showed significant deviation from normality. More non-normal distributions were observed in Group 2 than in Group 1. Significant differences were determined between the two sub-groups for the non-decongested data. The entire group of subjects was homogeneous for the decongested data. The subjective assessment of nasal patency appeared not to be a sufficient criterion for the selection of subjects for normative studies in rhinomanometry. The presence of anatomical abnormalities and the influence of the nasal cycle could be responsible for the skewness of nasal resistance data in the normative studies in rhinomanometry.