On the first 3 days of mechanical ventilation, mean Vts were 7.9 ± 1.2; 8.0 ± 1.0; 7.8 ± 0.9 ml / kg IBW, levels of mean FiO2 were 64 ± 16; 63 ± 18; 52.5 ± 17.1%, and levels of mean PEEP were 10.5 ± 3.2; 10, 1 ± 2.8, 8.6 ± 3.0 cmH2O.