Why Nasal Airways Experience Drying During Nasal-applied Continuous Positive Airway Pressure Therapy
White, DE; Bartley, J; Nates, R
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Introduction Since its introduction over thirty years ago, users of nasal‐applied continuous positive air pressure (n‐CPAP) therapy have commonly reported symptoms associated with airway drying. Here the normally robust ability of the human nose to heat and humidify inhaled ambient air seems to be incapacitated during n‐CPAP breathing. Despite n‐CPAP therapy being highly efficacious in resolving upper airway occlusion it is maligned with poor treatment compliance associated with user discomfort caused by airway drying. Relief from these symptoms is commonly provided by supplementary humidification however the causes(s) of airway drying remains speculative, and whether or not supplementary humidification is a solution has not been determined. During ambient breathing one nasal airway normally conducts the majority of airflow for a period of time before swapping sides in what is termed the ‘nasal cycle’. This variation enables the ASL in one nasal passageway to remain fully hydrated, facilitating effective mucociliary transport, while the other side experiences ASL dehydration as a result of it carrying out the bulk of air‐conditioning duty. Change in the status of the nasal cycle enables each side of the nose to experience periods of tissue rest and recovery.