Clinical study of n-CPAP elicited change in nasal airflow partitioning as potential cause of mucosal drying

Introduction: While the functional purpose of the nasal cycle is unknown, it is thought to enable the patent airway to undertake the air-conditioning functions, while the congested side undergoes a period of rest and recovery. Users of nasal continuous positive air pressure (n-CPAP) commonly experience adverse symptoms associated with airway drying. The current literature suggests nasal tissue compliance responses to pressurised breathing are the same within both airways. From this, pressure elicited changein nasal airflow partition ratio is not considered a potential cause of symptoms associated with airway drying. Aim: This investigation seeks to determine if a pressure elicited change in inter-nasal airflow apportionment occurs during n-CPAP breathing. Method: Twenty healthy volunteers wore a custom nasal mask fitted with air velocity sensors within each naris air channel. All breathed ambient air for the first twenty minutes and then pressurised air (10 cmH 2 0) for another twenty minutes. Results: Sixteen out of the twenty participants demonstrated a pressure elicited change in their nasal airflow partition ratio. This manifested itself with the patent airway demonstrating a reduction in airflow while the congested airway experienced an increase in airflow. This result is significant (Fisher9s exact test, p=0.03) and suggests the congested nasal airway may not be experiencing a period of rest during n-CPAP breathing. Conclusion: Our findings demonstrate that change in inter-nasal airflow apportionment occurs during n-CPAP breathing may disable the noses9 ability to regulate airway rest and recovery.