Total lung injury scores after 4 h of ventilation. Semiquantitative lung injury scores were significantly lower in the high-frequency oscillatory ventilation (HFOV)-9 Hz ventilated group than all the other three treatment groups. ## P < 0.01 versus HFOV-3 Hz. + P < 0.05 and ++ P < 0.01 versus HFOV-6 Hz. §§ P < 0.01 versus conventional mechanical ventilation (CMV).