The 48-hour enrollment time window begins when the first three criteria are met. If a patient meets the first three inclusion criteria but has a pulmonary arterial wedge pressure (PAOP) greater than 18 mm Hg, then the first four criteria must persist for more than 12 hours after the PAOP has declined to less than or equal to 18 mm Hg, and still be within the 48-hour enrollment window.