Figure 1.

Alterations during PP in PaO₂/FiO₂, PaCO₂, plateau pressure (Pplat) and alveolar dead space (VD_alv/V_T) in responders (solid lines) and nonresponders (dotted lines) according to PaO₂/FiO₂ changes. "PaO₂ responders" were defined by an increase in PaO₂/FiO₂ > 20 mmHg after 15 hours of PP (PP H15). Shown are box and whisker plots. Median = horizontal line inside the box; upper and lower quartiles = whisker plot. Boxes and triangles represent values higher or lower than the upper or lower quartiles. *P < 0.05 for comparison of changes in responders versus nonresponders. PP: prone position.