Network investigators have developed a plan for a new protocol to assess the Pulmonary Artery Catheter as a management tool in ARDS. The new study was prompted by recommendations from the FDA/NIH Pulmonary Artery Catheter Clinical Outcomes workshop convened in August 1997 in response to concerns in the medical community regarding the clinical benefit and safety of pulmonary artery catheters. The new protocol in the Fluids and Catheters Treatment Trial (FACTT) is a two by two factorial design comparing the patients receiving PAC or a central venous catheter (CVC) with one of two fluid management strategies (conservative vs. liberal). The randomized, multicenter trial is designed to include 1000 patients. The primary endpoint is mortality at 60 days. Secondary endpoints include ventilator free days and organ failure free days.