1. Borges, Amato, et al6 describe a PEEP titration following a maximal recruitment protocol and compare it to the open lung approach (PEEP set at Pflex + 2 cm H2O). Following a maximal recruitment strategy (described above), PEEP was set at 25 cm H2O and decreased by 2 cm H2O every 4 minutes until PaO2 + PaCO2 < 380 mm Hg, then increased by 2 cm H2O (optimal PEEP, mean 20±5 cm H2O). Using this strategy, PaO2 was sustained at levels above 400 mm Hg at 30 minute followup in all 24 patients (see Figure 4, top), and above 450 in the 16 patients followed for 6 hours. This correlated with a percent mass of collapsed tissue as measured by CT scan of <5% at end of PEEP titration and at 30 minute followup (see Figure 4, bottom).