Computational fluid dynamics investigation on effects of uvulopalatopharyngoplasty on upper airway stability

Yan Shang,Guoping Yin,Song Fu,Bin Hu,Jingying Ye

doi:10.1063/5.0053326

Abstract

Uvulopalatopharyngoplasty (UPPP) is a widely accepted surgery to treat patients with obstructive sleep apnea. However, the outcomes of surgery are variable and not satisfactory in many cases. To explore the key factors that influence outcomes of surgery from perspectives of upper airway stability using computational fluid dynamics methods, three-dimensional (3D) upper airway models were reconstructed, and a series of steady-state and unsteady-state simulations were performed based on computerized tomography (CT) scans of five normal subjects and preoperative and postoperative CT scans of ten obstructive sleep apnea (OSA) patients. Aerodynamics in normal subjects, preoperative OSA patients, and postoperative OSA patients was compared, and the outcomes of UPPP were analyzed from perspectives of upper airway resistance and the wall pressure–inspiratory pressure ratio. The negative pressure on the collapsible part of the upper airway was a major contributor to the obstruction. Surgery mitigated the negative pressure by reducing the upper airway resistance as well as the wall pressure–inspiratory pressure ratio. The effect of UPPP was associated with the change in resistance and the wall pressure–inspiratory pressure ratio.

Highlights

Obstructive sleep apnea (OSA) is a widespread sleep-related breathing disorder characterized by recurrent obstruction of the upper airway during sleep.1 The obstruction is usually accompanied by a decrease in oxygen saturation and wakefulness, which may lead to cardiovascular and metabolic diseases in the long term.2 prompt and effective treatment is essential.3 Currently, continuous positive airway pressure (CPAP) is the gold standard for the treatment of OSA
Computational fluid dynamics (CFD) has been widely used in studies related to the respiratory system because of its ability to provide detailed flow characteristics, and the results are shown to be accurate and valuable in comparison with experimental results and clinical observations,11 which are more informative than traditional medical imaging such as computerized tomography (CT) or magnetic resonance imaging (MRI)
Since the airway is compliant, negative intraluminal pressure has an important influence on the stability of the airway, and patency or obstruction is the result of the interaction between negative intraluminal pressure and the force of the surrounding dilating muscles and tissues

Summary

Introduction

Obstructive sleep apnea (OSA) is a widespread sleep-related breathing disorder characterized by recurrent obstruction of the upper airway during sleep. The obstruction is usually accompanied by a decrease in oxygen saturation and wakefulness, which may lead to cardiovascular and metabolic diseases in the long term. prompt and effective treatment is essential. Currently, continuous positive airway pressure (CPAP) is the gold standard for the treatment of OSA. Uvulopalatopharyngoplasty (UPPP) is one of the conventional surgical procedures for the treatment of OSA.. Previous studies have found that morphologic changes such as the minimum cross-sectional area of the upper airway are highly correlated with surgical outcomes, the mechanism of UPPP remains unclear, resulting in relatively low long-term surgical outcomes.. Various treatments for OSA have been studied by CFD before, such as oral appliance and maxillomandibular advancement surgery.. Due to the complexity in velopharyngeal surgery, previous CFD scitation.org/journal/adv studies are not sufficient to guide surgeons in improving their surgical protocols. We aimed at using CFD to compare the upper airway flow characteristics of normal, pre-UPPP, and postUPPP patients to clarify the mechanism of UPPP and to predict the outcome of the procedure

Methods

Results

Conclusion