Trial of Steroids in Pediatric Acute Lung Injury/ARDS

Inclusion Criteria: 1. Between 1 month and 18 years of age; AND 2. Admitted to the PICU with a diagnosis of ALI or ARDS, as defined by: 1. acute onset of the disease, 2. PaO2/FiO2 ratio \<300, 3. evidence of bilateral infiltrates on chest radiography, and 4. no evidence of cardiac dysfunction; AND 3. Intubated and mechanically ventilated. Exclusion Criteria: 1. Underlying disease requiring steroids \>0.5mg/kg/day of methylprednisolone (eg. Asthma) 2. HIV positive, or have any other congenital or acquired immunodeficiency; 3. Terminally ill patients or patients on hospice care or if there is a lack of commitment to aggressive intensive care 4. Cytotoxic therapy within the past 3 weeks 5. Major gastrointestinal bleeding within last 1 month 6. Extensive burns (\>20% total body surface area of full- or partial-thickness burns) 7. Known or suspected adrenal insufficiency 8. Vasculitis or diffuse alveolar hemorrhage 9. Bone marrow or lung transplant 10. Disseminated fungal infections 11. Severe chronic liver disease 12. Other conditions with estimated 6-month mortality of 50% or higher