- For 12-36 hrs. (ideally 12-24 hrs) after diagnosis of ARDS, patient must be ventilated as follows: Volume A/C, Tidal volume of 4-8 ml/kg PBW, Plateau pressure ≤ 30 cmH2O, PEEP/FIO2 adjustments using ARDSnet table, Ventilator rate to keep PaCO2 = 35-60 mmHg