ARDSnet Protocol vs. Open Lung Approach in ARDS

Inclusion Criteria: * Intubated and mechanically ventilated * Diagnosis of ARDS using American-European consensus criteria * Enrollment in study \< 48 hours since diagnosis of ARDS * 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 * During the 12-36 hour(ideally 12-24 hr) period, PaO2/FIO2 must remain \< 200 mm Hg for an ABG obtained 30 minutes after placement on the following specific ventilator settings: Volume A/C, Tidal volume = 6 ml/kg PBW, Plateau pressure ≤ 30 cmH2O, Inspiratory time ≤ 1 second, PEEP ≥ 10 cmH2O, FIO2 ≥ 0.5, Ventilator rate to keep PaCO2 = 35-60 mmHg * No lung recruitment maneuvers or adjunct therapy. * Total time on mechanical ventilation \< 96 hrs. at time of randomization. Exclusion Criteria: * Age \< 18 years or \> 80 years * Weight \< 35 kg PBW * Body mass index \> 60 * Intubated 2° to acute exacerbation of a chronic pulmonary disease * Acute brain injury (ICP \> 18 mmHg) * Immunosuppression 2° to chemo- or radiation therapy * Severe cardiac disease(one of the following): New York Heart Association Class 3 or 4, acute coronary syndrome or persistent ventricular tachyarrhythmias * Positive laboratory pregnancy test * Sickle cell disease * Neuromuscular disease * High risk of mortality within 3 months from cause other than ARDS, e.g. cancer * More than 2 organ failures (not including pulmonary system) * Documented lung barotrauma, i.e. chest tube placement other than for fluid drainage * Persistent hemodynamic instability or intractable shock * Penetrating chest trauma * Enrollment in another interventional study