The objectives of this trial are to determine whether, in critically ill patients with severe acute kidney injury (AKI), randomization to accelerated initiation of renal replacement therapy (RRT), compared to standard initiation, leads to:

1. Improved survival (primary outcome); and
2. Recovery of kidney function (principal secondary outcome), defined as independence from RRT at 90 days

Acute kidney injury (AKI) is a common and devastating complication of critical illness. Once AKI is established, treatment is largely supportive and no intervention has been found to restore kidney function or improve overall survival. Renal replacement therapy (RRT), usually in the form of hemodialysis, is frequently needed to manage patients with severe AKI. Such patients have an in-hospital mortality that consistently exceeds 50% with delays in RRT initiation implicated as a possible contributor. A recent meta-analysis suggested that earlier initiation of RRT may improve survival, but this is based on data derived overwhelmingly from observational studies. The investigators recently completed a multi-centre randomized controlled pilot trial that confirmed the feasibility of allocating patients to two different strategies of RRT initiation. Patient recruitment and follow-up, as well as patient safety, were successfully demonstrated during the pilot phase of this research program. The optimal timing of RRT initiation is an existing knowledge gap and a clear priority for investigation.

Inclusion Criteria:

1. Age ≥ 18 years

2. Admission to an intensive care unit (ICU)

3. Evidence of kidney dysfunction [serum creatinine ≥100 µmol/L (women) and ≥ 130 µmol/L (men)]

4. Evidence of severe AKI defined by at least 1 of the following 3 criteria:

   i) ≥ 2-fold increase in serum creatinine from a known pre-morbid baseline or during the current hospitalization; OR ii) Achievement of a serum creatinine ≥ 354 µmol/L with evidence of a minimum increase of 27 µmol/L from pre-morbid baseline or during the current hospitalization; OR iii) Urine output < 6.0 mL/kg over the preceding 12 hours

Exclusion Criteria:

1. Serum potassium > 5.5 mmol/L

2. Serum bicarbonate < 15 mmol/L

3. Presence of a drug overdose that necessitates initiation of RRT

4. Lack of commitment to ongoing life support (including RRT)

5. Any RRT within the previous 2 months (either acute or chronic RRT)

6. Kidney transplant within the past 365 days

7. Known pre-hospitalization advanced chronic kidney disease, defined by an estimated glomerular filtration rate < 20 mL/min/1.73 m2

8. Presence or clinical suspicion of renal obstruction, rapidly progressive glomerulonephritis, vasculitis, thrombotic microangiopathy or acute interstitial nephritis

9. Clinician(s) caring for patient believe(s) that immediate RRT is mandated

10. Clinician(s) caring for patient believe(s) that deferral of RRT initiation is mandated

    • at their discretion, clinicians may administer a bolus of intravenous furosemide (ie, "furosemide stress test") and evaluate the subsequent urine output to help guide decision making regarding the likelihood of AKI progression