Nasal cavity dimensions in the newborn measured by acoustic reflections

The acoustic refections technique was used to measure nasal cavity dimensions in 27 newborns. The results were expressed in terms of curves describing cross-sectional area as a function of the distance into the nose. From these curves, a mean curve with 95% confidence limits, nasal cavity volumes between the nostril and 4.5 cm into the nasal cavity (V₄₅ = 1.05 (0.24) cm³), the cross-sectional area at the narrowest site (A_min = 0.114 (0.033) cm²), and the distance from the nostril to A_min (D_Amin = 1.14 (0.47) cm), expressed as mean and SD were calculated. There was a weak correlation between A_min and length and weight at birth, but otherwise nasal cavity dimensions did not correlate with sex, race, birth weight, birth length, head circumference, or duration of gestation. Comparison of the curves from the newborns with curves from adults showed a facial growth in vertical/transverse directions (area) of 600% and anterior/posterior directions of 120%. The technique of acoustic rhinometry is noninvasive, and can be performed rapidly, and is therefore eminently suitable for pediatric application. Further investigations are needed to demonstrate the value as a diagnostic tool in pathological cases.