Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, PA 18015, United States.
Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, PA 18015, United States.
Med Eng Phys. 2014 Jun;36(6):647-58. doi: 10.1016/j.medengphy.2014.01.010. Epub 2014 Mar 18.
A large Eddy simulation (LES) based computational fluid dynamics study was performed to investigate gas transport and mixing in patient specific human lung models during high frequency oscillatory ventilation. Different pressure-controlled waveforms (sinusoidal, exponential and square) and ventilator frequencies (15, 10 and 6Hz) were used (tidal volume=50mL). The waveforms were created by solving the equation of motion subjected to constant lung wall compliance and flow resistance. Simulations were conducted with and without endotracheal tube to understand the effect of invasive management device. Variation of pressure-controlled waveform and frequency exhibits significant differences on counter flow pattern, which could lead to a significant impact on the gas mixing efficiency. Pendelluft-like flow was present for the sinusoidal waveform at all frequencies but occurred only at early inspiration for the square waveform at highest frequency. The square waveform was most efficient for gas mixing, resulting in the least wall shear stress on the lung epithelium layer thereby reducing the risk of barotrauma to both airways and the alveoli for patients undergoing therapy.
一项基于大涡模拟（LES）的计算流体动力学研究旨在探讨高频振荡通气期间特定患者人体肺模型中的气体输送和混合。使用了不同的压力控制波形（正弦、指数和方形）和呼吸机频率（15、10 和 6Hz）（潮气量=50mL）。这些波形是通过求解运动方程并施加恒定的肺壁顺应性和流动阻力来创建的。进行了有和没有气管内管的模拟，以了解有创管理设备的影响。压力控制波形和频率的变化对逆流模式有显著影响，这可能对气体混合效率产生重大影响。在所有频率下，正弦波都存在类似 Pendelluft 的流动，但在最高频率下，方形波仅在早期吸气时发生。对于气体混合来说，方形波是最有效的，从而使肺上皮层的壁面剪切应力最小，从而降低了接受治疗的患者气道和肺泡发生气压伤的风险。
