Airflow of the Two-Port Velopharyngeal Closure: Study Using Computational Fluid Dynamics

Area of Science:

• Aerodynamics
• Medical Engineering
• Speech Pathology

Background:

• Posterior pharyngeal flap (PPF) palatoplasty is a surgical technique to restore velopharyngeal (VP) closure.
• This procedure characteristically results in two residual ports between the nasal and oral cavities.
• Healthy individuals typically possess a single, movable port for VP function.

Purpose of the Study:

• To investigate and compare the airflow dynamics in the upper airway of patients with PPF reconstruction versus healthy subjects.
• To hypothesize differences in airflow patterns due to the distinct VP structures (two-port vs. one-port).

Main Methods:

• Utilized multislice spiral computed tomography scans from twenty adult PPF patients.
• Developed a two-cylinder model to simulate the two-port VP structure post-PPF.
• Employed real-time computational fluid dynamics (CFD) simulations to analyze airflow velocity and pressure through varying port sizes.
• Recorded airflow characteristics across four VP closure conditions: adequate, adequate/borderline, borderline/inadequate, and inadequate.

Main Results:

• Demonstrated significant differences in airflow dynamics between the two-port VP structure (PPF patients) and the one-port structure (healthy subjects).
• Airflow velocity and pressure were found to be dependent on the total orifice area of the VP ports.
• The two-port airflow model accurately mimicked the distinct airflow characteristics observed after PPF.

Conclusions:

• The airflow dynamics in the upper airway are significantly influenced by the VP structure.
• The two-port model effectively captures the unique airflow characteristics resulting from PPF palatoplasty, differing substantially from normal one-port VP function.
• Findings highlight the importance of considering the specific anatomical alterations post-PPF when analyzing airway function.