Inclusion Criteria:

• Adult patients (age > 18) admitted to the hospital through the emergency department (ED)
• At high risk of developing ALI (Lung Injury Prediction Score-LIPS greater than or equal to 4)

Exclusion Criteria:

• Anti-platelet therapy on admission or within 7 days prior to admission
• Presented to outside hospital ED > 12 hrs before arrival at site's facility
• Inability to obtain consent within 12 hours of hospital presentation
• Admitted for elective surgery
• Acute lung injury prior to randomization
• Receiving mechanical ventilation through a tracheostomy tube prior to current hospital admission (patient who is ventilator dependent)
• Presence of bilateral pulmonary infiltrates on admission if he or she has a history of bilateral pulmonary infiltrates (as evidenced by previous x-rays) that can reasonably explain the current degree of pulmonary infiltrates present.
• Presentation due to pure heart failure and no other known risk factors for ALI.
• Allergy to aspirin or non steroidal anti inflammatory drugs (NSAID's)
• Bleeding disorder
• Suspected active bleeding or judged to be at high risk for bleeding
• Active peptic ulcer disease (within past 6 months)
• Severe chronic liver disease
• Inability to administer the study drug
• Expected hospital stay < 48 hours
• Admitted for comfort or hospice care
• Patient, surrogate or physician not committed to full support (Exception: a patient will not be excluded if he/she would receive all supportive care except for attempts at resuscitation from cardiac arrest)
• Not anticipated to survive > 48 hours
• Previously enrolled in this trial
• Enrolled in a concomitant intervention trial
• Pregnant or breastfeeding