ABSTRACT
<p><b>OBJECTIVE</b>To investigate the normal ranges of the following parameters: nasal airway resistance (NAR), nasal cavity volume (NCV), nasopharyngeal volume (NPV) and nasal minimal cross sectional area (NMCA), and the effect of postural changes on nasal cavity geometry and nasal airway resistance.</p><p><b>METHODS</b>Seventy three healthy children had acoustic rhinometry (AR) test in different body positions.</p><p><b>RESULTS</b>In each group, the NAR of the healthy children in the lateral, and supine positions were significantly greater than that in the sitting position, and there were no significant differences among the NAR in lateral, and supine positions; the total NCV, NPV, NMCA of the healthy children in the lateral and supine positions were significantly smaller than that in the sitting position (P < 0.05). The NAR of the 3-6 year-old group was significantly greater than that of the 7-10 and 11-14 year-old groups, significant differences were also found between the last two groups; NAR in 7-10 year-old group were greater than that in the 11-14 year-old group (all P < 0.05). The total NCV,the total NPV and the total NMCA of the 3-6 year-old group were significantly smaller than that of the 7-10 and 11-14 year-old groups, significant differences were also found between the last two groups (all P < 0.05). All three parameters' numerical value in 7-10 year-old group were smaller than that in the 11-14 year-old group.</p><p><b>CONCLUSIONS</b>Postural changes may alter the NAR and the nasal cavity geometry in normal children.</p>