The ratio PaO2 / FiO2 has also increased, corresponding to the time T1, T2, T3 and T4 were: 213.94 ± 51.82, 335.43 ± 82.49, 412.54 ± 92.72 and 383.38 ± 50.54 (PaO2 and PaO2/FiO2 were significant differenced with p < 0.05).