Physiological change in nasal patency in response to changes in posture, temperature, and humidity measured by acoustic rhinometry

Background: Acoustic rhinometry has been used to assess nasal patency and to calculate nasal cavity volume. This study used acoustic rhinometry to assess changes in nasal patency after alterations in posture, unilateral mechanical obstruction, temperature, and humidity. Methods: Eight healthy adult volunteer subjects underwent acoustic rhinometry during the following conditions: (1) sitting position (control), (2) supine position, (3) left lateral recumbent position, (4) nostril unilaterally mechanically blocked, (5) ice pack on neck, (6) drinking cold water, (7) drinking hot water, (8) nasal nebulizer, and (9) oxymetazoline decongestant. Results: Two distinct patterns emerged based on the total nasal cavity volumes in response to the decongestant, Subjects with initial unilateral nasal cavity volumes near the mean had an expected increase in total volume after the topical decongestant administration. There were two subjects with initial volumes of 1 SD above the mean that had a paradoxical decrease in total volume in response to the decongestant. In all subjects, there was a significant decrease in the volume of each of the nasal cavities in response to ingestion of hot water at 1 minute. There was a significant decrease in the volume of the smaller of the two nasal cavities in response to nebulizer treatment and hot water ingestion at 5 minutes. Total nasal cavity volume changes were not significant for any of the variables. Conclusion: Changes in nasal cavity volumes were detected by acoustic rhinometry after alterations in posture, unilateral mechanical obstruction, temperature, and humidity. Nebulizer treatment and hot water ingestion caused a significant decrease in nasal volume. The nose of a healthy patient was able to adapt to environmental and physiological changes to maintain a consistent total nasal volume within 15 minutes.