5, in the presence of diffuse bilateral SB431542 infiltrates on the chest X-ray, with the involvement of all lung

fields, pulmonary capillary pressure (PCP) < 18 mmHg not due to heart failure, pleural effusion, or bacterial pneumonia. In the following year, Fowler et al.15, in a study with several centers investigating 68 patients with ARDS, used the following as diagnostic criteria: acute onset of bilateral pulmonary infiltrates; PCP ≤ 12 mmHg; lung compliance ≤ 50 mL/cmH2O; and PaO2 and alveolar oxygen pressure ratio (PaO2/PAO2) ≤ 0.2. Given the diversity of criteria used for the diagnosis of ARDS and seeking to expand the definition of the syndrome, in 1988 Murray et al.16 incorporated risk factors to the definition, as well as the relative brevity of the disease process and severity measures. Regarding risk factors, the authors pointed to the need for identifying whether the syndrome was caused by aspiration GSI-IX order pneumonia, medications, or inhalation of toxic gases, or if it was associated with systemic events such as sepsis, multiple trauma, or acute pancreatitis. Severity was assessed using the lung injury score (LIS), incorporating physiological data indicators of oxygenation, PEEP values, and compliance and distribution of radiological lesions (Table 1). The score included the evaluation of

four criteria: 1) chest X-ray, 2) hypoxemia score (PaO2/FiO2); 3) PEEP level; and 4) respiratory system compliance score (Crs) (when available). Although the Murray score is still used, it has not been validated, that is, it has not been established whether patients with scores of the same value correspond to similar levels of lung injury, and thus, have the same prognosis. Additionally, the LIS has several problems,

such as: it does not consider the effect of time on injury severity (acute or chronic event); the score is not specific for ARDS, patients with cardiogenic pulmonary edema Edoxaban are identified as having ARDS; and patients with mild volume overload, for any reason, can be diagnosed as having ARDS, as it is not mandatory to obtain the PCP levels to rule out cardiogenic edema.8, 17 and 18 In 1994, experts from the United States and Europe met to improve the definition of ARDS, aiming to improve the standardization of research, the criteria for more accurately determining the severity, and disease prognosis.19 Formally, two different conditions were defined, acute lung injury (ALI) and ARDS itself (Table 2), as diseases in which there is a sudden and acute onset of respiratory distress, bilateral infiltrates on the chest X-ray in the frontal view, absence of left atrial hypertension (PCP ≤ 18 mmHg when measured or no clinical evidence of left ventricular failure), and severe hypoxemia, evaluated by PaO2/FiO2 ratio.