Fig. 8. Effective mean tissue elastance (μ  ^H ) and heterogeneity index (σ  ^H ) for all 11 dogs. Data are shown at baseline (ˆ) and after lung injury (•). Values are presented as mean ± SD. * Significantly higher from baseline data at same mean airway pressure (  P̄^ao ) using two-tailed paired  t test. † Significantly higher from corresponding data at 10, 15, and 20 cm H²O at same condition using analysis of variance and least significant difference criterion .