Understanding the Role of Genes and Biomarkers in the Inflammation and Blood Clotting Process in Children With Acute Lung Injury

Inclusion Criteria: * Hospitalized and requiring supplemental oxygen * Meets the American-European consensus definition of ALI/ARDS, defined as partial pressure of oxygen in arterial blood/fraction of inspired oxygen (PaO2/FiO2) ratio of less than 300 mm Hg, bilateral opacities on a chest radiograph, and either a pulmonary wedge pressure of less than 18 mm Hg or the absence of clinical evidence of left atrial hypertension * Acute pulmonary parenchymal disease (i.e., onset of bilateral infiltrates on chest radiograph within 48 hours of screening) * PaO2/FiO2 less than or equal to 300 mm Hg, regardless of the mean airway pressure * At least one arterial blood gas confirming partial pressure of oxygen/fraction of inspired oxygen (PO2/FiO2) ratio less than 300 mm Hg or Fi02/Sao2 on pulse oximetry of less than 320 Exclusion Criteria: * Clinical signs of left ventricular failure, pulmonary capillary wedge pressure greater than 18 mm Hg, or evidence, such as echocardiography, suggesting a cardiac basis for the pulmonary edema * Presence of right-to-left intracardiac shunt