General Medical Information

Collapsible Segments

Thomas V. Mccaffrey

Consideration of the resistance properties of the nasal airway often entails the implicit assumption that the walls of the nasal cavity are rigid. This is valid for flow in the bony cavum of the nasal airway, but it is not for the compliant region of the nasal vestibule and valve. The lateral pressure within a conduit depends on the rate of flow, according to the Bernoulli principle. As airflow accelerates through a constriction, lateral pressure decreases. Compliance of the area of constriction can allow collapse. Collapse of the nasal valve can occur, and this factor can lead to a nonlinear pressure-flow relation. Collapse is characterized by an asymmetric pressure-flow curve during the inspiration and expiration flow limitation occurring on inspiration.