use of intermittent hemodialysis and continuous venovenous hemofiltration (cvvh) (a type of continuous hemodialysis). among critically ill patients, intensive renal replacement therapy with cvvh does not appear to improve outcomes compared to less intensive intermittent hemodialysis. however, other clinical and health economic studies demonstrated that, initiation of crrt is associated with a lower likelihood of chronic dialysis and was cost-effective compared with irrt in patients with acute kidney injury. complications metabolic acidosis, hyperkalemia, and pulmonary edema may require medical treatment with sodium bicarbonate, antihyperkalemic measures, and diuretics. lack of improvement with fluid resuscitation, therapy-resistant hyperkalemia, metabolic acidosis, or fluid overload may necessitate artificial support in the form of dialysis or hemofiltration. however, oliguria during anesthesia may predict aki, but the effect of a fluid load is highly variable. striving toward a predefined urine output target to prevent aki is futile. early recovery of aki aki recovery can be classified into three stages 1–3 on the basis of the inverse of the aki kdigo serum creatinine criteria. prognosis mortality mortality after aki remains high. aki has a death rate as high as 20%, which may reach up to 50% in the intensive care unit (icu). each year, around two million people die of aki worldwide. aki develops in 5% to 30% of patients who undergo cardiothoracic surgery, depending on the definition used for aki. if aki develops after major abdominal surgery (13.4% of all people who have undergone major abdominal surgery) the risk of death is markedly increased (over 12-fold). kidney function depending on the cause, a proportion of patients (5–10%) will never regain full kidney function, thus entering end-stage kidney failure and requiring lifelong dialysis or a kidney transplant. patients with aki are more likely to die prematurely after being discharged from hospital, even if their kidney function has recovered. the risk of developing chronic kidney disease is increased (8.8-fold). epidemiology new cases of aki are unusual but not rare, affecting approximately 0.1% of the uk population per year (2000 ppm/year), 20x incidence of new eskd (end-stage kidney disease). aki requiring dialysis (10% of these) is rare (200 ppm/year), 2x incidence of new eskd. there is an increased incidence of aki in agricultural workers because of occupational hazards such as dehydration and heat illness. no other traditional risk factors, including age, bmi, diabetes, or hypertension, were associated with incident aki. acute kidney injury is common among hospitalized patients. it affects some 3–7% of patients admitted to the hospital and approximately 25–30% of patients in the intensive care unit. acute kidney injury was one of the most expensive conditions seen in u.s. hospitals in 2011, with an aggregated cost of nearly $4.7 billion for approximately 498,000 hospital stays. this was a 346% increase in hospitalizations from 1997, when there were 98,000 acute kidney injury stays. according to a review article of 2015, there has been an increase in cases of acute kidney injury in the last 20 years which cannot be explained solely by changes to the manner of reporting. history before the advancement of modern medicine, acute kidney injury was referred to as uremic poisoning while uremia was contamination of the blood with urine. starting around 1847, uremia came to be used for reduced urine output, a condition now called oliguria, which was thought to be caused by the urine's mixing with the blood instead of being voided through the urethra. acute kidney injury due to acute tubular necrosis (atn) was recognized in the 1940s in the united kingdom, where crush injury victims during the london blitz developed patchy necrosis of kidney tubules, leading to a sudden decrease in kidney function. during the korean and vietnam wars, the incidence of aki decreased due to better acute management and administration of intravenous fluids.