Extravascular lung water and pulmonary arterial wedge pressure for fluid management in patients with acute respiratory distress syndrome

In a recent review of the data for fluid strategies and ARDS, fluid restriction or diuretic use was graded as "reasonably justifiable by available scientific evidence" and as "strongly supported by expert critical care opinion". Until the ARDS Network trial is published, only general guidelines regarding fluid management with or without specific vascular filling pressures from a pulmonary artery catheter can be made. Ultimately, the rationale for restricting fluid is to reduce hydrostatic pressures as much as possible. It seems most reasonable to maintain the lowest PAOP in ARDS patients that still maintains adequate circulating blood volume, mean arterial perfusion pressures, and cardiac output to provide sufficient oxygen delivery. Other clinical variables such as central venous pressure, urinary output, acid-base status, and lactate, serum urea nitrogen, and serum creatinine levels may help in judging the adequacy of a patient's intravascular volume, especially if central vascular pressure measurements are not available. Measures to reduce total body water, including flood restriction and diuretic use, seem to be of some benefit. Vasopressor use is especially important when systemic perfusion pressures are inadequate to maintain organ blood flow but should not be used to create supranormal levels of oxygen delivery.