Numerical and experimental study of steady-state CO2 and inert gas washout.
Numerical and experimental study of steady-state CO2 and inert gas washout.
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稳态 CO2 和惰性气体冲洗的数值和实验研究。
DOI：
10.1152/jappl.1988.64.3.1022
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Neufeld,GR
中科院分区：
文献类型：
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作者：
Scherer,PW;Gobran,S;Aukburg,SJ;Baumgardner,JE;Bartkowski,R;Neufeld,GR
稳态CO2和输注He和六氟化硫（SF6）冲洗的单路径喇叭-铃铛数值模型的预测进行了比较与健康志愿者的实验测量。所用的数学模型是一个经典的气道对流扩散方程的数值解，在肺泡端增加了一个分布源项。在人体研究中，使用静态采样技术测量静脉输注饱和两种惰性气体混合物的生理盐水期间CO2、He和SF6的呼出浓度和III相斜率。我们发现实验确定的标准化斜率（第三阶段斜率除以混合呼气浓度）和数值确定的标准化斜率之间有很好的一致性，模型中没有自由参数，除了上气道死腔，潮气量，呼吸频率和呼吸模式（正弦）的生理参数。我们得出的结论是：1）与具有分布源项的气道对流扩散方程结合使用的单路（韦伯）喇叭形解剖模型足以描述正常肺中CO2和输注He和SF6的稳态肺冲洗; 2）将潮气量与功能残气量分开的界面面积，气体通过其扩散到运动的潮气量中，对相位III的归一化斜率产生主要影响。
The predictions of a single-path trumpet-bell numerical model of steady-state CO2 and infused He and sulfur hexafluoride (SF6) washout were compared with experimental measurements on healthy human volunteers. The mathematical model used was a numerical solution of the classic airway convention-diffusion equation with the addition of a distributed source term at the alveolar end. In the human studies, a static sampling technique was used to measure the exhaled concentrations and phase III slopes of CO2, He, and SF6 during the intravenous infusion of saline saturated with a mixture of the two inert gases. We found good agreement between the experimentally determined normalized slopes (phase III slope divided by mixed expired concentration) and the numerically determined normalized slopes in the model with no free parameters other than the physiological ones of upper airway dead space, tidal volume, breathing frequency, and breathing pattern (sinusoidal). We conclude 1) that the single-path (Weibel) trumpet-bell anatomic model used in conjunction with the airway convection-diffusion equation with a distributed source term is adequate to describe the steady-state lung washout of CO2 and infused He and SF6 in normal lungs and 2) that the interfacial area separating the tidal volume fron from the functional residual capacity gas, through which gas diffusion into the moving tidal volume occurs, exerts a major effect on the normalized slopes of phase III.