1. received continuous mechanical ventilation \> 7 days 2. known or clinically suspected elevated intracranial pressure (\>18mmhg) necessitating strict control of paco2 3. known pregnancy 4. broncho-pleural fistula 5. severe liver disease (child-pugh score ≥ 10) 6. bmi \>40kg/m2 7. anticipating withdrawal of life support and/or shift to palliation as the goal of care 8. patient is receiving ecmo at time of randomization

1. received continuous mechanical ventilation \> 7 days 2. known or clinically suspected elevated intracranial pressure (\>18mmhg) necessitating strict control of paco2 3. known pregnancy 4. broncho-pleural fistula 5. severe liver disease (child-pugh score ≥ 10) 6. bmi \>40kg/m2 7. anticipating withdrawal of life support and/or shift to palliation as the goal of care 8. patient is receiving ecmo at time of randomization

received continuous mechanical ventilation > 7 days known or clinically suspected elevated intracranial pressure (>18mmhg) necessitating strict control of paco2 known pregnancy broncho-pleural fistula severe liver disease (child-pugh score ≥ 10) bmi >40kg/m2 anticipating withdrawal of life support and/or shift to palliation as the goal of care patient is receiving ecmo at time of randomization

received continuous mechanical ventilation > 7 days known or clinically suspected elevated intracranial pressure (>18mmhg) necessitating strict control of paco2 known pregnancy broncho-pleural fistula severe liver disease (child-pugh score ≥ 10) bmi >40kg/m2 anticipating withdrawal of life support and/or shift to palliation as the goal of care patient is receiving ecmo at time of randomization

1. received continuous mechanical ventilation > 7 days 2. known or clinically suspected elevated intracranial pressure (>18mmhg) necessitating strict control of paco2 3. known pregnancy 4. broncho-pleural fistula 5. severe liver disease (child-pugh score ≥ 10) 6. bmi >40kg/m2 7. anticipating withdrawal of life support and/or shift to palliation as the goal of care 8. patient is receiving ecmo at time of randomization

1. received continuous mechanical ventilation > 7 days 2. known or clinically suspected elevated intracranial pressure (>18mmhg) necessitating strict control of paco2 3. known pregnancy 4. broncho-pleural fistula 5. severe liver disease (child-pugh score ≥ 10) 6. bmi >40kg/m2 7. anticipating withdrawal of life support and/or shift to palliation as the goal of care 8. patient is receiving ecmo at time of randomization

1. received continuous mechanical ventilation > 7 days 2. known or clinically suspected elevated intracranial pressure (>18mmhg) 3. known pregnancy 4. broncho-pleural fistula 5. severe liver disease (child-pugh score ≥ 10) 6. bmi >40kg/m2 7. anticipating withdrawal of life support and/or shift to palliation as the goal of care 8. patient is receiving ecmo

1. received continuous mechanical ventilation > 7 days 2. known or clinically suspected elevated intracranial pressure (>18mmhg) 3. known pregnancy 4. broncho-pleural fistula 5. severe liver disease (child-pugh score ≥ 10) 6. bmi >40kg/m2 7. anticipating withdrawal of life support and/or shift to palliation as the goal of care 8. patient is receiving ecmo