指示肺通气不均匀性的熵变及其同其他指标的理论比较

Entropy Change As Indication of Lung Ventilation Inhomogeneity and Its Theoretical Comparison with Other Indices

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。Entropy change of ventilation(ECV) was used to indicate lung ventilation inhomogeneity.ECV is defined as the limit of entropy change from uneven ventilation to even ventilation per molar inspired gas when alveolar tidal volurne approaches zero。Equa-tion for calculation of ECV was derived from the basic formula of entropy in this study,Mathematical model lungs were used for comparison of ECV with other 7 washout indices。It was found that ECV depends on ventilation distribution only while the other 7 washout indices depend not only on ventila-tion distribution but also on tidal volume and deadspace,thus the validity of evaluating ventilation inho-mogeneity is affected.Another advantage of ECV is that it gives a direct visual medel of ventilation in-honeity。