1. Recruitment Maneuver (RM) - Continuous positive airway pressure of up to 45 cmH2O for 40 s at an FiO2 of 1.0 plus subsequent PEEP, FiO2 titration so that SaO2=90-95%, or PaO2=60-80 (An additional RM may be administered at 5 and 10 hours after the original RM)