I.D.E.A.L.-I.C.U. (Initiation of Dialysis EArly Versus Late in Intensive Care Unit)

Inclusion Criteria:

Adults (males or females, age >18 years) with severe sepsis or septic shock who develop acute renal failure (as defined by the "injury" stage of the RIFLE classification) will be eligible for inclusion.

Severe sepsis is defined as the presence of suspected or documented infection, systemic inflammatory response syndrome (SIRS) and at least one sign of hypoperfusion or organ dysfunction:

• Neurological (encephalopathy with Glasgow score <13),
• Respiratory (PaO2/FiO2 <300 mmHg)
• Hematological (platelet count < 100,000/mm3)
• Hepatic (bilirubinemia >2mg/dL)
• Metabolic acidosis (lactates >2.5 mMol/L or base deficit >5 mEq/L or HCO3─< 18mEq/L)
• Circulatory (systolic arterial blood pressure <90 mmHg or drop of at least 40 mmHg in normal blood pressure in the absence of any other cause of hypotension)

SIRS is defined as the simultaneous presence of at least 2 of the following criteria :

• Body temperature ≥ 38°C ou ≤ 36°C
• Heart rate ≥ 90 bpm
• Respiratory rate ≥ 20/mn or PaCO2 ≤ 32 mmHg
• Leucocytes ≥ 12,000/mm3 or ≤ 4,000/mm3 or >10% immature forms.

Septic shock is defined as severe sepsis with persistent hypotension despite adequate vascular filling and/or need for intropic or vaso-active drugs.

Acute renal insufficiency is defined as the "injury" stage of the RIFLE classification, i.e. the presence of at least one of the following criteria:

• Increased creatinine x 2 times the baseline value
• Decrease of >50% in glomerular filtration rate (GFR)
• Oliguria < 0.5 ml/kg/h for 12 hours

All patients are required to provide informed consent after having been appropriately informed about the study. In case of temporary incapacity of the patient to sign, the consent form can be signed by a surrogate.

Exclusion Criteria:

Patients presenting any of the following criteria will not be eligible for inclusion in the study:

1. Patients with chronic renal failure classified beyond the "injury" stage according to the RIFLE classification at dialysis.
2. Patients already presenting emergency criteria for immediate hemodialysis at the time of randomization (i.e. hyperkalemia >6.5 mmol/L or pH<7.15 or pulmonary oedema by fluid overload)
3. Patients aged less than 18 years
4. Pregnant women.
5. Moribund patients whose life expectancy is less than 24 hours
6. Patients unlikely to survive to 28 days because of uncontrollable comorbidities (e.g. cardiac, pulmonary or hepatic disease at the terminal stage, hepatorenal syndrome, uncontrolled cancer, severe post-anorexic encephalopathy…)
7. Patients with advance directives indicating their wish not to be resuscitated.
8. Patients under legal guardianship.