Fig. 5.
Gas volumes used in the strain calculations for the studied combinations of PEEP and VT levels. Plots in the first three columns (left) depict combinations of VT and PEEP. In these plots, the x-axes represent the gas volume of the depicted gas volume component as a percentage of the regional end-inspiratory gas volume (Vgas,EIr). The y-axes show eight ROIs from the most dependent (ROI 2) to the most nondependent (ROI 9). Represented are the gas volumes corresponding to the regional tidal volume (VTr), regional gas volume at functional residual capacity (VFRCr), regional end-expiratory gas volume (Vgas,EEr), regional gas volume recruited with PEEP (Vrec,PEEPr), and regional gas volume recruited with VT at end-expiration (Vrec,EE,VTr). The rightmost column displays the absolute regional gas volume at end-inspiration in each ROI for the three studied PEEP and VT conditions. Although Vgas,EEr and VFRC are superimposed for PEEP = 0, Vgas,EEr > VFRC as PEEP increases. Data are shown as the mean ± SD of all animals.