Acute lung injury in children is a syndrome of rapid onset of acute respiratory failure and require admission into intensive care units (ICU) for advanced life support. There are almost no information on epidemiology of acute lung injury. Published studies do not have information for an entire year and none of them have evaluated the degree of oxygenation failure under standard ventilator settings. The investigators will perform a 1-year prospective audit of all patients admitted with acute lung injury in a network of pediatric ICUs in Spain.

We will evaluate oxygenation under standard ventilator settings (FiO2 0.5 and 1 on PEEP 5 or 10 cmH2O) in pediatric acute respiratory distress syndrome.

Outcome measures will include: overall ICU mortality, number of patients meeting ARDS criteria at 24 hours, and stratification of patients depending on PaO2/FiO2 ratio at 24 h of meeting acute respiratory distress syndrome criteria.

Inclusion Criteria:

• Acute onset of respiratory failure
• Age 1 month to 18 years old
• Bilateral pulmonary infiltrates on Chest X-ray
• Absence of left ventricular failure, PaO2/FiO2>300 mmHg

Exclusion Criteria:

• None

Children from 1 month to 18 years old, admmitted into ICU, and meeting the American-European Consensus Conference definition for acute lung injury (ALI).