School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.
Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
Sci China Life Sci. 2019 Feb;62(2):235-243. doi: 10.1007/s11427-018-9373-y. Epub 2018 Sep 12.
A better understanding of airflow characteristics in the upper airway (UA) is crucial in investigating obstructive sleep apnea (OSA), particle sedimentation, drug delivery, and many biomedical problems. Direct visualization of air flow patterns in in-vitro models with realistic anatomical structures is a big challenge. In this study, we constructed unique half-side transparent physical models of normal UA based on realistic anatomical structures. A smoke-wire method was developed to visualize the air flow in UA models directly. The results revealed that the airflow through the pharynx was laminar but not turbulent under normal inspiration, which suggested that compared with turbulent models, a laminar model should be more suitable in numerical simulations. The flow predicted numerically using the laminar model was consistent with the observations in the physical models. The comparison of the velocity fields predicted numerically using the half-side and complete models confirmed that it was reasonable to investigate the flow behaviors in UA using the half-side model. Using the laminar model, we simulated the flow and evaluated the effects of UA narrowing caused by rostral fluid shift on pharyngeal resistance. The results suggested that fluid shift could play an important role in the formation of hypopnea or OSA during sleep.
更好地了解上呼吸道 (UA) 的气流特征对于研究阻塞性睡眠呼吸暂停 (OSA)、颗粒沉积、药物输送以及许多生物医学问题至关重要。在具有真实解剖结构的体外模型中直接可视化气流模式是一个巨大的挑战。在这项研究中，我们基于真实的解剖结构构建了独特的半侧透明物理 UA 模型。开发了烟雾线方法来直接可视化 UA 模型中的气流。结果表明，在正常吸气时，通过咽的气流是层流而不是湍流，这表明与湍流模型相比，层流模型在数值模拟中应该更合适。使用层流模型预测的流场与物理模型中的观察结果一致。使用半侧和完整模型预测的速度场的比较证实，使用半侧模型研究 UA 中的流动行为是合理的。使用层流模型，我们模拟了气流，并评估了因颅液移位导致 UA 变窄对咽阻力的影响。结果表明，流体移位在睡眠期间呼吸暂停或 OSA 的形成中可能起重要作用。
