Oliguria and fluid overload.

Oliguria is a very common clinical situation that is also often difficult to interpret since it may represent either the expression of a disease or an appropriate response of the kidneys to extracellular volume depletion or decreased renal blood flow. In patients with acute kidney injury, oliguria is independently associated with mortality. Fluid overload is a complication of the impaired sodium and water excretion observed in patients with oliguric acute kidney injury. Fluid overload leads not only to cardiopulmonary complications such as congestive heart failure and pulmonary edema requiring mechanical ventilation but also to several others such as delayed wound healing, tissue breakdown, and impaired bowel function. The aim of this short review is to point out the deleterious effects of these two related clinical situations emphasizing their pathophysiology.