Acute renal failure

Rapid decrease in the glomerular filtration rate, occurring over minutes to days.

Termed asotemia or accumulation of nitrogenous wastes.

Renal failure does not have exact biochemical or clinical criteria for definition.

Rate of renal excretion of metabolic waste products is inadequate with increased serum concentrations of urea and creatinine.

Renal failure differs from renal insuffiency as the latter where renal function is abnormal but is capable of sustaining essential bodily functions.

Causes divided into prerenal, postrenal and intrinsic.

Defined as anuric when urine volume is <50 mL for 24 hours, oliguric when volume is <500 mL for 24 hours and non oliguric when volume is from 500-6000 mL for 24 hours, and polyuric for urine output greater than 6000 mL for 24 hours.

Prerenal azotemia is a functional response to renal hypoperfusion, with preservation of renal tissues.

With a lack of renal function the creatinine generally rises about 2 mg per kg of body weight per day.

In hospitalized-acquired cases mortality ranges from 40% to more than 75% when associated with multiple organ dysfunction syndrome.

Affects approximately 2-7% of hospitalized patients.

Affects more than 35% of critically ill patients.

Renal replacement therapy is the mainstay of treatment.

Renal replacement required in 5-6% of critically ill patients and its use is associated with in hospital mortality rates of 50-80%.

A reduction in 28 day mortality from 46% with alternate day dialysis to 28% with daily dialysis (Schiffl).

A reduction in mortality noted (Ronco) from 59% to 43% when ultra filtration increased from 20-35 ml per kg per hour during continuous venovenous hemo-filtration.

A reduction in mortality reported from 61% to 41% when an increased rate of continuous venovenous hemo-filtration utilized (Saudan).

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