The Artificial Kidney Initiation in Kidney Injury 2

Inclusion Criteria: All of the following criteria must be fulfilled to be included in the observational study (first stage): * Adults (\>18 years) * Hospitalized in a study ICU. * Evidence of acute kidney injury compatible with the diagnosis of acute tubular necrosis in a context of ischemic or toxic aggression and who receive (or received for the same episode) invasive mechanical ventilation and/or catecholamine infusion. * Acute kidney injury stage 3 of KDIGO classification defined by at least one of the following criteria: serum creatinine concentration of more than 4 mg/dl (354 µmol/liter) or greater than 3 times the baseline creatinine level, anuria (urine output of 100 ml/day or less) for more than 12 hours, oliguria (urine output below 0.3 ml/kg/h or below 500 ml/day) for more than 24 hours. To be randomized (randomization stage), supplemental criteria must be fulfilled. These criteria can appear either immediately after inclusion in the observational stage, or during the follow-up of the patient in the observational stage, in the absence of any non-inclusion criteria (listed below) at the time of randomization: * Oliguria/anuria (urine output \<0.3 ml/kg/h or \<500 ml/day) for more than 72 hours or serum urea concentration comprised between 40 and 50 mmol/l. * Affiliation to a social security regime Exclusion Criteria: * Severity criteria mandating immediate RRT initiation (Table 1) * Serum urea level \> 50 mmol/l * Severe chronic renal failure (defined by a cre…