Racial differences in nasal fossa dimensions determined by acoustic rhinometry

Sixty acoustic rhinographs from subjects of three different ethnic groups (Caucasian [Europeans], Negro, and Oriental) were examined at baseline and after decongestion. The main parameters analysed were minimal cross-sectional area (MCA), the distance at which this occurred (D), nasal volume at 0-4 cm (Vol), mean cross-sectional area at 0-6 cm (MA), and the cross-sectional area at 10 points in the nose (0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, and 6 cm) analysed as a series (A). Values from left and right were combined and mean values used. Analysis was carried out using multiple linear regression and grouped linear regression with analysis of covariance and, for A, multifactorial analysis of variance. For MCA, race was the main determining factor with Orientals and Caucasians significantly lower than Negroes: p<0.0001 (corrected means and 95% confidence intervals [c.i.]: Orientals: 0.63 cm2, 0.55-0.71 cm2; Caucasians: 0.69 cm2, 0.62-0.77 cm2; Negroes: 0.87 cm2, 0.79-0.95 cm2). Height alone correlated with D in the decongested state (p<0.0001); race as well as height in non-decongested noses (p = 0.018). There were significant racial differences in Vol in both decongested (p = 0.014), and non decongested noses (p<0.0001). In the non-decongested state MA was significantly different in all racial groups: p<0.0001 (corrected means and c.i.: Orientals: 3.89 cm2, 3.47-4.31 cm2; Caucasians: 4.67 cm2, 4.27-5.09 cm2; Negroes: 5.13 cm2, 4.72-5.53 cm2). In the decongested state there was a significant difference between Negroes and the other two groups (p = 0.015), and Orientals and Caucasians were a homogenous population. We conclude that race has a significant effect on acoustic rhinometry measurements and this needs to be taken into account.