Obstructive sleep apnea (OSA) is a common disorder which may need to be treated by the upper respiratory tract (URT) surgery. To increase the success rate of the URT surgery, it is crucial to understand the flow features in the URT models. In this work, the turbulent flow characteristics in four 3D anatomically accurate URT models reconstructed from two OSA subjects with successful and failed surgery are numerically studied by the large-eddy simulation (LES) and unsteady Reynolds-averaged Navier-Stokes (RANS). The features of velocity fields, pressure fields, and wall shear stress fields as well as the spectral analysis of wall shear stress between successful and failed surgery are explored. The results indicate that LES is capable of capturing flow patterns and flow oscillation and is effective for OSA surgery prediction. Even if the unsteady RANS can obtain the correct pressure drop across the airways, it may not be appropriate to be used for surgery prediction. Moreover, it is found that the quality of oscillating signal of wall shear stress is a key factor in surgery prediction. In a successful surgery, the wall shear stress oscillation is always strong, and the oscillating signal can perform a dominant frequency near 3~5 Hz, while in a failed surgery it does not show this clear intrinsic property. The results not only will gain new insights in the URT surgical planning but also will improve the prediction of surgical outcome for OSA patients.

中文翻译：

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两位手术成功和失败的阻塞性睡眠呼吸暂停患者上呼吸道的血流模拟

阻塞性睡眠呼吸暂停 (OSA) 是一种常见疾病，可能需要通过上呼吸道 (URT) 手术进行治疗。为了提高 URT 手术的成功率，了解 URT 模型中的流动特征至关重要。在这项工作中，通过大涡模拟 (LES) 和非定常雷诺平均 Navier-Stokes (RANS) 对从两个手术成功和失败的 OSA 受试者重建的四个 3D 解剖学准确 URT 模型中的湍流特性进行了数值研究。探讨了手术成功与失败之间的速度场、压力场和壁面剪应力场的特征以及壁面剪应力的频谱分析。结果表明 LES 能够捕捉流动模式和流动振荡，对 OSA 手术预测有效。即使不稳定的 RANS 可以获得正确的气道压降，也可能不适合用于手术预测。此外，发现壁面剪应力振荡信号的质量是手术预测的关键因素。在成功的手术中，壁面剪应力振荡总是很强的，振荡信号可以在3~5Hz附近表现出主导频率，而在失败的手术中，它没有表现出这种明显的内在特性。该结果不仅将为 URT 手术计划提供新的见解，而且还将提高对 OSA 患者手术结果的预测。发现壁面剪应力振荡信号的质量是手术预测的关键因素。在成功的手术中，壁面剪应力振荡总是很强的，振荡信号可以在3~5Hz附近表现出主导频率，而在失败的手术中，它没有表现出这种明显的内在特性。该结果不仅将为 URT 手术计划提供新的见解，而且还将提高对 OSA 患者手术结果的预测。发现壁面剪应力振荡信号的质量是手术预测的关键因素。在成功的手术中，壁面剪应力振荡总是很强的，振荡信号可以在3~5Hz附近表现出主导频率，而在失败的手术中，它没有表现出这种明显的内在特性。该结果不仅将为 URT 手术计划提供新的见解，而且还将提高对 OSA 患者手术结果的预测。