Influence of lung injury and PEEP on VRI VT measurement: ANCOVA.

Slopes and intercepts for the different measurement points (BLH: baseline healthy; ALI-0: impaired lungs (ALI) at zero PEEP; ALI-5: ALI at PEEP 5 mbar; ALI-10: ALI at PEEP 10 mbar; ALI-15: ALI at PEEP 15 mbar) are presented on the left. Descriptive measures of the differences in VT measured by VRI and EIT, displayed as mean±SD (standard deviation) and range [ml] are presented on the right. To investigate the influence of lung damage and PEEP on EIT and VRI VT measures, an ANCOVA was used to test the equality of slopes and intercepts (using an F test to compare a global model where slope is shared among the data sets, with a model where each dataset gets its own slope). The first P-value tested the null hypothesis that the slopes are all identical (the lines are parallel). The second P-value represents the results of testing the null hypothesis that the intercepts are identical.

左侧展示了不同测量位点的斜率与截距，涵盖以下组别：BLH（baseline healthy，基础健康状态）、ALI-0（零呼气末正压[PEEP, Positive End-Expiratory Pressure]下的急性肺损伤[ALI, Acute Lung Injury]）、ALI-5（PEEP为5 mbar时的ALI）、ALI-10（PEEP为10 mbar时的ALI）、ALI-15（PEEP为15 mbar时的ALI）。右侧则呈现了通过VRI与电阻抗断层成像（Electrical Impedance Tomography, EIT）测得的潮气量（Tidal Volume, VT）差值的描述性统计结果，以均值±标准差（standard deviation, SD）及范围[ml]的形式展示。为探究肺损伤与PEEP对EIT及VRI VT测量结果的影响，本研究采用协方差分析（Analysis of Covariance, ANCOVA）检验斜率与截距的等同性：通过F检验对比两类模型，一类为全局模型（所有数据集共享同一斜率），另一类为各数据集拥有独立斜率的模型。首个P值用于检验“所有斜率均一致（即各组拟合直线相互平行）”的原假设；第二个P值则对应“截距均一致”的原假设检验结果。