A dynamic and direct visualization model for the study of nasal airflow.

OBJECTIVE: To evaluate nasal airflow characteristics during physiologic breathing in normal and pathologic conditions.
DESIGN: The choana of an anatomical human model was connected to a pump that simulated physiological pressure changes in the upper airway system. Normal ambient air was used as medium. The airstream was marked with aerosolized water particles, and was observed through an exact but translucent replica of the original nasal septum.
RESULTS: In physiologic conditions the airflow is mixed. Turbulence is clearly visible even with low flow velocities. There is less turbulence with lower flow rates. The nasal airflow follows a triphasic pattern of acceleration, near-steady state, and deceleration. Turbulence is prominent in the first and third phases. The main flow stream passes through the middle meatus at all rates. Hypertrophic mucosal membranes and turbinates increase the proportion of air passing the middle meatus. With decongested turbinates, flow distribution is more even. After turbinectomy there is a significant amount of airflow passing along the floor of the nose. The olfactory region is aerated only toward the end of inspiration and during the entire expiration phase.
CONCLUSIONS: This model allows the investigation of airflow distribution and turbulence under physiologic conditions and the examination of the influence of pathologic conditions on these parameters. Overzealous trimming of turbinates results in an unphysiologic distribution of airflow.