Acute Kidney Injury & Failure

Acute Kidney Injury & Failure

Acute kidney injury (AKI) is a rapid deterioration in renal function that is not immediately reversible by altering factors such as blood pressure, intravas-cular volume, cardiac output, or urinary flow. The hallmark of AKI is azotemia and frequently oligu-ria. Azotemia may be classified as prerenal, renal, and postrenal. Moreover, the diagnosis of renal azotemia is one of exclusion; thus, prerenal and postrenal causes must always be excluded. How-ever, not all patients with acute azotemia have kid-ney failure. Likewise, urine output of more than 500 mL/d does not imply that renal function is nor-mal. Basing the diagnosis of AKI on creatinine lev-els or an increase in blood urea nitrogen (BUN) is also problematic because creatinine clearance is not always a good measure of glomerular filtration rate. The criteria developed by the Acute Kid-ney Injury Network are now most often usedto stage AKI . AKI is diagnosed by documenting an increase in serum creatinine of more than 50%, or an absolute increase of 0.3 mg/dL, and a reduction in urine output to less than 0.5 mL/kg/h for 6 h or longer, with all findings developing over 48 h or less.