The PROBE Fluid UK randomised controlled trial compares a protocol-based fluid removal strategy with usual care in critically ill patients with acute kidney injury receiving kidney replacement therapy.

Severe acute kidney injury (AKI) in the intensive care unit (ICU) is almost uniformly complicated by fluid accumulation, often leading to fluid overload. Congestion resulting from fluid accumulation is believed to contribute to organ failure. Removal of excess fluid is a central component of dialysis treatment, also known as kidney replacement therapy (KRT). However, there remain important knowledge gaps in our ability to remove excess fluid effectively and safely. If fluid is removed too slowly, fluid overload and its complications persist for longer. If fluid is removed too fast during KRT, patient's blood pressure may drop (ie hemodynamic instability may occur) which may precipitate complications.

The optimal fluid management strategy is currently unknown.

The PROBE Fluid UK study is a randomized clinical trial comparing a protocol-based fluid removal strategy with usual care in critically ill patients with AKI receiving KRT. The fluid management protocol is intended to achieve neutral or negative daily fluid balance by both preventing and treating fluid accumulation.

The primary objective of this trial is to determine whether the intervention results in a difference in cumulative fluid balance from day of randomization to 5 days later. Secondary outcomes will include short-term patient outcomes, safety outcomes, and health resource utilization related to KRT delivery.

Inclusion Criteria:

1. Adult patients aged ≥18 years
2. Admitted to the intensive care unit
3. Acute kidney injury defined by the KDIGO criteria
4. Planned initiation of KRT within 12 hours or the receipt of KRT for AKI for ≤48 hours

Exclusion Criteria:

1. Lack of commitment to maintain kidney, pharmacologic or respiratory support at the time of screening, or probable transition to comfort care within 48 hours according to the treating clinician
2. Probable discharge from the ICU within 48 hours according to treating clinician
3. Severe burn injury (>10% of body surface area)
4. Severe abnormality in serum sodium (>155 or <120 mmol/L)
5. Important ongoing fluid losses are present and/or are expected to require continued maintenance IV fluids during the next 48 hours
6. The clinical care team believes that the proposed intervention is inappropriate