- at least 2 of the following criteria: plasma lactate > 2 mmol/L or unexplained metabolic acidosis (pH < 7.3); hypoxemia defined by PaO2 < 70 mmHg at room air or a PaO2/FiO2 ratio < 280 mmHg (or < 200 mmHg if pneumonia was the source of sepsis) or need for mechanical ventilation; urine output < 30 mL/h for at least 2 hours despite a fluid challenge of at least 500mL; a platelet count < 100,000/mm3, a decrease of 50% from previous value, or unexplained coagulopathy (prothrombin time < 60% and elevated fibrin degradation products > 10 μg/mL);