Effect of Head Posture on Airflow and Pressure Behavior of Human Upper Airway During Snoring

Abstract

Snoring is a common breathing disorder during sleep. It is hypothesized that head posture during sleep could change the bending angle and the cross-sectional area of the airway, which could cause changes in airflow and aerodynamic pressure during sleep. In this work, an experiment-driven computational study was conducted to examine the aerodynamics and pressure behavior in human upper airway during snoring. An anatomically accurate human upper airway model associated with a dynamic uvula was reconstructed from human magnetic resonance image (MRI) and high-speed photography. The airway bending at different head posture and the corresponding change in airway cross-sectional area are modeled based on measurements from literature. An immersed-boundary-method (IBM)-based direct numerical simulation (DNS) flow solver was adopted to simulate the corresponding unsteady flows of the bent airway model in all their complexity. Analyses were performed on vortex dynamics and pressure fluctuations in the pharyngeal airway. It was found that the vortex formation and aerodynamic pressure were significantly affected by the airway bending. A head-neck junction extension posture tends to facilitate the airflow through the upper human airway. Fast Fourier transformation (FFT) analysis of the pressure time history revealed the existence of higher order harmonics of base frequency with significant pressure amplitudes and energy intensities. The results of this study help better understand the pathology of snoring under the influence of head posture from an aerodynamic perspective.