Stratification of the Acute Respiratory Distress Syndrome - A Second Phase Study (STANDARDS-2)

In 2012, an update of the ARDS definition (The Berlin criteria) was published and an empirical classification was proposed according to three PaO2/FiO2 cut-off values at ARDS onset: severe (≤100 mmHg), moderate (>100 - ≤200 mmHg), and mild (>200 - ≤300 mmHg) on positive end-expiratory pressure (PEEP) ≥5 cmH2O. However, despite that there is sufficient evidence about the interactions between PEEP and FiO2, these cut-off values did not mandate the assessment of hypoxemia under standardized guidelines.

The PaO2/FiO2 can be easily manipulated. Alterations in PEEP and FiO2 can dramatically change the PaO2/FiO2. Despite recent reports on the effects of standardized ventilator settings on PaO2/FiO2, is still a matter of debate whether the assessment of hypoxemia must be performed at 24 hours instead of at ARDS onset, and whether the assessment of hypoxemia under standardized ventilator settings is the most appropriate tool for stratifying lung severity in patients with ARDS.

The investigators will examine whether the values of relevant variables (including age, plateau pressure, driving pressure, compliance, PaO2/FiO2) at 24 after ARDS diagnosis under standardized ventilator settings have an impact on the stratification and prediction of death in ARDS patients. This study is an extension of the study NCT02288949.