Baseline characteristics of the ARDS cohort with direct lung injury.

All values represent means ± SD unless otherwise specified.1p-values based on the following tests: t-test for variables presented as means, Wilcoxon rank-sum test for variables presented as the median, Fisher's exact test of association for categorical variables.除非另有说明，所有数值均以平均值±标准差（standard deviation, SD）表示。1. P值基于下述检验方法：对于以平均值呈现的变量采用t检验（t-test），对于以中位数呈现的变量采用威尔科克森秩和检验（Wilcoxon rank-sum test），对于分类变量（categorical variables）采用费舍尔精确关联检验（Fisher's exact test of association）。