The objective of this study is to evaluate the association between positive end-expiratory pressure (PEEP) setting and cardiac function, as measured by cardiac index, in patients with acute respiratory distress syndrome (ARDS) who were managed on the NHLBI ARDS Network Fluid and Catheter Treatment Trial (FACTT) fluid protocols.

This is a secondary cross-sectional analysis of the FACTT multi-center randomized controlled trial enrolling adult patients within 48 hours of ARDS onset from twenty medical centers across the US, some of which included more than one hospital. We studied the patients who were randomized to the pulmonary artery catheter arm of the FACTT study. The investigators included patients that had PEEP and cardiac index measurements performed within a short period of each other during the first 3 days of the FACTT study enrollment. Since FACTT had a 2x2 factorial design, half of the patients were in a 'liberal fluids' study arm, and the other half were in a 'conservative fluids' study arm.

Inclusion Criteria:

Acute lung injury diagnosis (as defined by The American - European Consensus Conference on ARDS) of < 48 hours in duration.

Patients in the Pulmonary Artery catheter (PAC) arm of the FACTT study. PaO2 / FiO2 ratio of < 200. Data from the first 3 days of mechanical ventilation.

Exclusion Criteria:

Select chronic conditions that could independently influence survival (e.g., expected 6-month survival < 50%) and / or ventilator weaning.

PEEP values missing. FiO2 values missing. PaO2 values missing. Cardiac index values missing Pressors and / or inotropes requirement.

This is a secondary cross-sectional analysis of the FACTT multi-center randomized controlled trial enrolling adult patients within 48 hours of ARDS onset from twenty medical centers across the US, some of which included more than one hospital. We studied the patients who were randomized to the pulmonary artery catheter arm of the FACTT study. We included patients that had PEEP and cardiac index measurements performed within a short period of each other during the first 3 days of the FACTT study enrollment.