Which dialysis method works best for ICU kidney failure? a Head-to-Head test

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Adults (\> or= 18 years old) in ICU 2. Receiving (or who have received) invasive mechanical ventilation and/or catecholamine infusion 3. Availability of both equipment IHD and CRRT (in the investigational center at the time of inclusion) 4. One of the 2 following situations 4.a: Either at least one of the 3 following complications of AKI\* (whatever the KDIGO stage): persistent severe hyperkalaemia despite medical treatment, persistent severe metabolic acidosis despite medical treatment or severe pulmonary edema due to fluid overload despite diuretic therapy 4.b: Or an AKI stage 3 of KDIGO with one of the 2 following criteria: serum urea concentration\>40mmol/L or persistence of oligo-anuria\>3 days \*Definitions of these complication are provided in the main text (Section 7.1) 5. Affiliation of social security system 6. Written consent obtained from the patients (from a support person, family member or a close relative if the patient is not able to expressing and sign consent) or inclusion without initial consent in case of emergency, if the patient is not able to express his/her consent and in the absence of support person, family member or a close relative Exclusion Criteria: * Moribund state (patient likely to die within 24h) * Previous inclusion in the study * Subject deprived of freedom, or under a legal protective measure (example: patients under guardianship or curatorship) * Subject receiving state medical aid * Pregnancy or breastfeeding woman * Patient included in another research trial on AKI * Advanced chronic kidney disease (CKD) defined by an estimated GFR\<20 mL/min/1.73 m2 * Presence of a drug overdose or of a dialyzable toxin that necessitates RRT (because IHD may be preferable in these conditions). * Presence or clinical suspicion of renal obstruction, rapidly progressive glomerulonephritis, vasculitis, thrombotic microangiopathy or acute interstitial nephritis * Brain injured patients or other causes of increased intracranial pressure * Fulminant hepatic failure