200 mmHg, but < 300 mmHg, on ventilator settings that include positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) > 5 cm H2O. Moderate .ARDS o The PaO2/FiO2 is >100 mmHg, but < 200 mmHg, on ventilator settings that include PEEP >5 cm H2O. Severe ARDS o The PaO2/FiO2 is < 100 mmHg on ventilators setting that include PEEP > 5 cm H2O. o To determine the PaO2/FiO2 ratio, the PaO2 is measured in mmHg and the FiO2 is expressed as a decimal between 0-21 and 1.">