Effects of Miniscrew-Assisted Rapid Palatal Expansion on Airflow in the Upper Airway of an Adult Patient with Obstructive Sleep Apnea Syndrome: Computational Simulation using Fluid-Structure Interaction

Abstract

The purpose of this study was to investigate the effects of miniscrew-assisted rapid palatal expansion (MARPE) on changes in airflow in the upper airway (UA) of an adult patient with obstructive sleep apnea syndrome (OSAS).

Three-dimensional (3D) UA models of a young adult male patient with OSAS [age of 18 years and 7 months, body mass index (BMI), 25.0 kg/m2

apnea and hypopnea index (AHI), 49.5 events/hour

respiratory disturbance index (RDI), 52.2 events/hour

lowest O2 saturation rate (LSR), 85%] were fabricated using cone-beam computed tomography images taken before (T0) and after MARPE treatment (T1). The signs [age of 19 years and 1 month, BMI, 24.9 kg/m2

AHI, 2.2 events/hour

RDI, 20.2 events/hour

LSR, 95%] and symptoms at the T1 stage significantly improved. A total of sixteen cross-sectional planes were set with the inter-plane distance of 10 mm along the upper airway: 7 planes for the nasal cavity and 9 planes for the pharynx. Using 3D computational fluid dynamics (3D-CFD) and fluid-structure interaction (FSI) analysis, changes in the cross-sectional area (CSA), velocity and pressure of airflow, displacements of nodes, and total resistance were investigated at maximum inspiration (MI), rest, and maximum expiration (ME).

Compared to the T0 stage, the T1 stage exhibited significant increase in CSA at the most of parts of the nasal cavity and at the upper part of pharynx. Velocity of airflow was decreased primarily in the anterior part of the nasal cavity at MI and ME, and in the upper and middle parts of the pharynx at MI. However, the amounts of decrease were greater in the nasal cavity than the pharynx. Pressure of airflow was decreased mainly in the anterior parts of the nasal cavity and consistently in the whole pharynx. In terms of node displacement, the amount of displacement was insignificant at both T0 and T1 stages. In aspects of total resistance, there was significant decrease in the absolute values at MI (-55.1%), rest (-35.9%) and ME (-33.9 %) during T0-T1.

Since MARPE improved airflow and reduced resistance in the UA, it might be an effective treatment modality for adult OSAS patients who have moderate to severe narrow basal arch and crowding and refuse to the oral appliance or MMA surgery.