A finite-element model of oxygen diffusion in the pulmonary capillaries
A finite-element model of oxygen diffusion in the pulmonary capillaries
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DOI：
10.1152/jappl.1997.82.6.2036
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发表时间：
1997-06-01
影响因子：
3.3
通讯作者：
Johnson, RL
中科院分区：
文献类型：
--
作者：
Frank, AO;Chuong, CJC;Johnson, RL
我们通过使用二维有限元模型确定了 O-2 扩散途径的总体肺扩散能力 (DL) 以及肺泡膜 (Dm) 和红细胞 (RBC) 段 (De) 的扩散能力，该模型用于表示肺毛细血管的片流特征。还考虑使用轴对称模型来评估几何配置的影响。结果显示，膜段贡献了主要阻力，而红细胞段阻力随着红细胞转运过程中 O-2 饱和度 (SO2) 的升高而增加：红细胞在毛细血管入口处贡献了总阻力的 7% (SO2 = 75%)，在毛细血管末端贡献了 30% (SO2 = 95%)，对于 45% 的血细胞比容 (Hct)。 Dm 和 DL 都随着 Hct 的增加而增加，但由于红细胞之间对 O-2 流入的竞争，开始接近 Hct 35% 附近的稳定状态。发现 Dm 和 DL 对血浆蛋白浓度的变化相对不敏感（2 与 4% 相似）（28 与 45% 相似）。轴对称结果显示所有 Her 和蛋白质浓度的趋势相似，但始终高估了扩散能力（类似于 2.2 倍），这主要是因为夸大了空气组织屏障表面积。二维模型与实验数据相关性相当好，可以更好地代表肺毛细血管床的 O-2 摄取。
We determined the overall pulmonary diffusing capacity (DL) and the diffusing capacities of the alveolar membrane (Dm) and the red blood cell (RBC) segments (De) of the diffusional pathway for O-2 by using a two-dimensional finite-element model developed to represent the sheet-flow characteristics of pulmonary capillaries. An axisymmetric model was also considered to assess the effect of geometric configuration. Results showed the membrane segment contributing the major resistance, with the RBC segment resistance increasing as O-2 saturation (SO2) rises during the RBC transit: RBC contributed 7% of the total resistance at the capillary inlet (SO2 = 75%) and 30% toward the capillary end (SO2 = 95%) for a 45% hematocrit (Hct). Both Dm and DL increased as the Hct increased but began approaching a plateau near an Hct of 35%, due to competition between RBCs for O-2 influx. Both Dm and DL were found to be relatively insensitive (2 similar to 4%) to changes in plasma protein concentration (28 similar to 45%). Axisymmetric results showed similar trends for all Her and protein concentrations but consistently overestimated the diffusing capacities (similar to 2.2 times), primarily because of an exaggerated air-tissue barrier surface area. The two-dimensional model correlated reasonably well with experimental data and can better represent the O-2 uptake of the pulmonary capillary bed.