Cheng Gary C, Koomullil Roy P, Ito Yasushi, Shih Alan M, Sittitavornwong Somsak, Waite Peter D
Department of Mechanical Engineering, University of Alabama at Birmingham, USA.
Department of Oral and Maxillofacial Surgery, University of Alabama at Birmingham, USA.
Math Comput Simul. 2014 Dec 1;106:44-59. doi: 10.1016/j.matcom.2012.11.008.
Obstructive sleep apnea syndrome is one of the most common sleep disorders. To treat patients with this health problem, it is important to detect the severity of this syndrome and occlusion sites in each patient. The goal of this study is to test the hypothesis that the cure of obstructive sleep apnea syndrome by maxillomandibular advancement surgery can be predicted by analyzing the effect of anatomical airway changes on the pressure effort required for normal breathing using a high-fidelity, 3-D numerical model. The employed numerical model consists of: 1) 3-D upper airway geometry construction from patient-specific computed tomographic scans using an image segmentation technique, 2) mixed-element mesh generation of the numerically constructed airway geometry for discretizing the domain of interest, and 3) computational fluid dynamics simulations for predicting the flow field within the airway and the degree of severity of breathing obstruction. In the present study, both laminar and turbulent flow simulations were performed to predict the flow field in the upper airway of the selected patients before and after maxillomandibular advancement surgery. Patients of different body mass indices were also studied to assess their effects. The numerical results were analyzed to evaluate the pressure gradient along the upper airway. The magnitude of the pressure gradient is regarded as the pressure effort required for breathing, and the extent of reduction of the pressure effort is taken to measure the success of the surgery. The description of the employed numerical model, numerical results from simulations of various patients, and suggestion for future work are detailed in this paper.
阻塞性睡眠呼吸暂停综合征是最常见的睡眠障碍之一。对于患有这种健康问题的患者进行治疗时，检测该综合征的严重程度以及每位患者的阻塞部位非常重要。本研究的目的是检验以下假设：通过使用高保真三维数值模型分析解剖气道变化对正常呼吸所需压力的影响，可以预测上颌下颌前移手术对阻塞性睡眠呼吸暂停综合征的治疗效果。所采用的数值模型包括：1）使用图像分割技术从患者特定的计算机断层扫描构建三维上气道几何结构；2）对数值构建的气道几何结构进行混合单元网格生成，以离散感兴趣的区域；3）进行计算流体动力学模拟，以预测气道内的流场和呼吸阻塞的严重程度。在本研究中，进行了层流和湍流模拟，以预测所选患者在上颌下颌前移手术前后上气道的流场。还研究了不同体重指数的患者，以评估其影响。对数值结果进行分析，以评估沿上气道的压力梯度。压力梯度的大小被视为呼吸所需的压力，压力降低的程度用于衡量手术的成功与否。本文详细介绍了所采用的数值模型、不同患者模拟的数值结果以及对未来工作的建议。
