The effect of minimum cross-sectional area site and size on upper airway flow field characteristics: a pilot study

This pilot study aims to analyze how the site and size of minimum cross-sectional area (CSAmin) affect the airflow characteristics in the upper airway models.

Eleven upper airway models were created, including three models with CSAmin at different sites and eight models with varying CSAmin sizes at the same site, then computational fluid dynamics (CFD) simulations were conducted.

The CFD results indicated that the maximum airflow velocity, minimum pressure, and maximum pressure difference consistently occurred at the CSAmin. The smaller the CSAmin, the greater the airflow velocity and pressure drop, the lower the minimum static pressure, and the higher the overall airway resistance.

The site and size of the CSAmin are critical to the airflow characteristics in the upper airway models. The location of the CSAmin may be the most likely site for airway collapse. Patients with a smaller CSAmin (<79mm2) may have a higher risk of obstructive sleep apnea.