Fig. 2

a Trend of median static compliance variation; b median local compliance variation compared to baseline (expressed in percentage); and c impact of prone positioning on median PaCO2 before, during, and after prone position for patients with an increase of the static compliance by ≥ 3 mL/cmH2O (PCG+) (red) and patients with static compliance < 3 mL/cmH2OsPP after 16-h of PP (PCG−) (black). PP: prone positioning; SP: supine positioning; *p < 0.005 vs. baseline for both PCG+ and PCG− patients; $p < 0.005 vs. baseline for PCG+ patients only