Fig. 1.  Time course of change in pulse pressure (ΔPP) and ΔPP indexed to tidal transpulmonary pressure (ΔPP/ΔP^tp) in control animals (A , C ) or animals with acute respiratory distress syndrome (ARDS) (B , D ) alternatively ventilated for 5–7 min with a tidal volume (V^T) of 10 ml/kg and a respiratory rate of 15 breaths/min (RR15) (•), a V^Tof 6 ml/kg and RR15 (▴), or a V^Tof 6 ml/kg and RR25 (▪). Data points are means with 95% confidence intervals; n = 8 animals. *P < 0.05; **P < 0.01 versus  baseline values (for control animals) and lavage values (for ARDS). †P < 0.05; †††P < 0.001 versus  baseline values.