Effects of size of the nasal airway on nasal airflow rate.

The controversy concerning the effects of nasal airway impairment on facial growth has stimulated renewed interest in upper airway respiratory function. We assessed the relationship between nasal airway patency and nasal airflow rate, using the pressure-flow technique to estimate nasal cross-sectional size and nasal airflow rate in 30 normal and 82 nasally impaired adults. Groups were categorized according to otolaryngologic examination results and pressure-flow measurements. The results clearly demonstrate that size of the airway influences airflow rate when the smallest nasal cross-sectional area is under 0.4 cm2. The data suggest that the nose becomes flow-limiting when it is less than 0.18 cm2. These data support our contention that nasal airway impairment in adults occurs when the airway is less than 0.4 cm2 in size.