Acute Kidney Injury

Acute Kidney Injury can be diagnosed by:

increase in serum creatinine of > mg/dL w/n 48 hrs
increase of serum creatinine of > 50% w/n 48 hrs
decrease in hourly urine output to < 0.5 mL/kg (ideal body weight) for more than 6 hours

When considering the cause of renal failure, etiologies can be classified as

pre-renal
renal
post-renal

Pre-renal

This injury occurs due to decreased renal blood flow. Since the damage occurs during the low flow state, improving flow in the moment may not immediately improve function once damage occurs.

Renal

Acute tubular necrosis (ATN) represents > 50% of AKI cases. It is an injury to epithelial cells that line the renal tubules. Etiologies inclu

Sepsis
radiocontrast dye
nephrotoxic drugs
rhabdomyolysis

Post-Renal

Approximately 10% of renal injury seen in the ICU is from post-renal injury. If obstruction of the renal system is prolonged, it can cause papillary necrosis of the distal collecting ducts.