新型冠状病毒肺炎患者肺泡内渗出液特性对气道开放压力影响的计算模拟

A computational simulation of the effect of alveolar exudates properties on airway opening pressure in patients with COVID-19

目的:研究新型冠状病毒肺炎重症患者远端气道内黏液粘度和表面张力变化对气道开放压力和黏液吸引压力的影响。方法:借助于气道开放的流体动力学模型,预测了气道内充满各种不同粘度和表面张力的黏液时,开启8~14级气道所需的压力以及黏液清除所需的吸引压力。结果:气道开放计算模型表明,当气道黏液具有类似药用甘油室温下的粘度或者呈现花生酱样的流变学特性时,气道开启压力可高达40~50 cmH 2O(1 cmH 2O=0.098 kPa);根据黏液粘度和表面张力的不同,吸痰所需的负压高达20 kPa以上,很有可能引起远端气道的关闭。结论:在一部分新型冠状病毒肺炎重症患者中,由于远端气道高粘度分泌物的存在,限制气道平台压≤30 cmH 2O,故不能保证这些气道的有效开放,且这些高粘度的分泌物很难用纤维支气管镜吸引清除。

Objective To investigate the effect of changes in the viscosity and surface tension of lower airway mucus on the airway opening pressure and the suction pressure in patients with severe COVID-19.Methods By using the fluid dynamic model of airway reopening,the pressure required to open 8-14 generations of pulmonary airways was predicted when these airways were filled with mucus of various viscosities and surface tensions.Moreover,the suction pressure needed for mucus removal was also estimated.Results Computational models of airway opening showed that when occlusion fluids had viscosity similar to that of medicinal glycerin at room temperature or presented rheological properties like peanut butter,the airway opening pressures could be as high as 40-50 cmH2O(1 cmH2O=0.098 kPa);the negative pressure needed for sputum suctioning could reach over 20 kPa,which is very likely to result in the closures of the distal airways.Conclusions In some critically ill patients with COVID-19,limiting plateau pressure to≤30 cmH2O may not guarantee the opening of airways due to the presence of highly viscous lower airway secretions.Furthermore,they couldn′t be removed by a fiberoptic bronchoscope.