指示肺通气不均匀性的熵变及其同其他指标的理论比较

• 作 者: 徐国林 杨森·Ｂ 粤尔森·Ｅ 伊万德·Ｅ
• 机 构: 航天医学工程研究所
• 出 处: 航天医学与医学工程
• 发表日期: 1995年03期
• 关键词: 肺通气 不均匀性 肺泡气体交换 熵变 潮气量 数学模型 洗出 死腔 计算方程 趋近

熵代表无序的水平，作者使用通气的熵变（ＥＣＶ）指示肺通气的不均匀性。ＥＣＶ定义为当肺泡潮气量趋近于零时每摩尔被吸入气体从不均匀通气到均匀通气的熵变的极限。本文从熵的基本公式导出了ＥＣＶ的计算方程。用几个数学模型肺将ＥＣＶ同其他７个洗出指标进行了比较。８个指标中，只有ＥＣＶ仅取决于通气分布。其他７个指标不仅取决于通气分布，还同潮气量和死腔的大小有关。这影响了用它们评价肺通气不均匀性的效果。ＥＣＶ的另一个优点是，它能给出通气不均匀性的直现的模型。

Entropy represents the level of disorder, and the author uses the Venous Entropy Change (ECV) to indicate non-uniformity of pulmonary ventilation. ECV is defined as the limit of entropy per mole of inhaled gas from non-uniform ventilation to uniform ventilation when alveolar tidal volume approaches zero. This paper derives the ECV calculation equation from the basic formula of entropy. Several mathematical models of lungs were used to compare ECV with the other 7 washout indicators. Of the eight indicators, only the ECV depends only on the ventilation distribution. The other seven indicators not only depend on the ventilation distribution, but also with the tidal volume and the size of the dead space. This affects their assessment of the effects of non-uniformity of pulmonary ventilation. Another advantage of ECV is that it gives a straightforward model of non-uniform ventilation.