Nasal airflow-during respiratory cycle

Background: Knowledge on the airflow patterns in the nasal cavity is essential to understanding the function of the nasal cavity. This study has attempted to observe the breath cycle of nasal airflow during respiration at rest. Methods: We constructed a nasal cavity model by rapid prototyping using 1.25-mm-thick CT data and devised a piston pump driven by a cam, to simulate respiration at rest. The airflow was evaluated with particle image velocimetry and visualized in coronal reconstructed images. Results: During the inspiration, a maximal velocity was observed at the valve area and the main stream occurred in the middle and superior airways. During the expiration, main stream was noted in the middle airway and was slow compared with the flow during inspiration. Vortexes were observed between inspiration and expiration. Conclusion: This result widens our knowledge of nasal airflow and this technique will allow a more physiological understanding of nasal operations.