Only limited data exist on the benefit of online hemodiafiltration in patient with Acute kidney injury. The objective of this pilot RCT is to assess the feasibility of a large multicentre RCT to determine whether, in patients with AKI requiring acute renal replacement therapy, does exposure to Online Hemodiafiltration reduce the inflammatory status and improve renal recovery compared to conventional intermittent hemodialysis at the ICU.

Despite sparse data on the advantages of hemodiafiltration over conventional hemodialysis for intermittent dialysis, there is limited data comparing these modalities in AKI from various aetiologies in critically ill patients. As RCTs involving renal replacement therapy at the ICU are exceptionally challenging to complete, thus a rigorous RCT based on appropriate sample size and relevant clinical outcomes is crucial. The objective of this pilot RCT is to assess the feasibility of a larger multicentre RCT to determine whether, in patients with AKI requiring acute renal replacement therapy, does exposure to Post-dilution Hemodiafiltration or Pre-dilution Hemodiafiltration reduce the inflammatory status and improve renal recovery compared to conventional intermittent hemodialysis at the ICU. As post-dilution HDF has never been adequately evaluated in an ICU context, comparison between pre-dilution and post-dilution HDF is also required to confirm feasibility.

This proof-of-concept pilot trial will focus on three feasibility endpoints. It will be considered successful if the following criteria are achieved :

• Protocol adherence: If ≥85% of overall dialysis sessions are administered per-protocol according to the allocated modality
• Adherence to follow-up: If it was possible to obtain end-of-study outcomes in ≥90% of participants, and
• Participant accrual: If the average monthly enrolment is 4 or more participants per months.

Inclusion Criteria:

• Hospitalised in the ICU
• Acute kidney injury stage 3 (KDIGO-AKI Criteria)
• Requiring RRT for AKI, as judged by the attending clinician (initiation) or conversion from CRRT to intermittent dialysis
• Adult of 18 years or more

Exclusion Criteria:

• Female subjects who are pregnant or breast-feeding or considering becoming pregnant during the study.
• Subjects who are participating in another study involving dialysis interventions
• Subjects or relatives/next-of-kin unable to provide written informed consent
• Creatinine clearance (CrCl) < 30 mL/min measured by 24-hour urine collection or eGFR or on chronic dialysis at baseline
• Subjects on active immunosuppressive therapy (>10mg of prednisone, biologic therapies, calcineurin inhibitors, mTOR inhibitors or antimetabolites)
• Subjects with active contraindication to anticoagulation during dialysis session
• Subjects whose RRT is not part of their life goal