Nasal airway dimensions in term neonates measured by continuous wide-band noise acoustic rhinometry

The nasal airways of 94 healthy term infants (37-42 weeks gestational age) were examined by continuous wide-band noise acoustic rhinometry under standardized conditions on the second or third day postpartum. Validation of the flexible infant probe on tubular plastic models with dimensions similar to the nasal cavity of newborn infants showed a correlation coefficient of 0.98. The mean and standard deviation (SD) of the total minimal cross-sectional area (TMCA), the distance from the nostril to the MCA (DMCA) and the total volumes between the nostril and 45 mm into the nasal cavity (TVOL45) were 0.20 +/- 0.05 cm(2), 0.76 +/- 0.29 cm and 2.14 +/- 0.39 cm(3) respectively. In general, both anthropometric and rhinometric mean values were higher in males (n = 52) compared to females (n = 42), and the difference was statistically significant for TMCA and head circumference. We conclude that the technical properties, small size and flexible tube of the miniprobe make it uniquely suited for objective assessment of the nasal airways in infants and small children. The RHIN 2000/2100 miniprobe (S.R. Electronics Aps, Lynge, Denmark) is the first infant probe commercially available, making standardization and comparison of results easier.