ICU · Renal
Acute kidney injury and renal replacement therapy
Also known as Acute kidney injury (AKI) · AKI · Renal replacement therapy (RRT) · CRRT · Continuous venovenous haemofiltration (CVVH) · Haemodialysis · KDIGO classification · AKIKI trial
AKI is an abrupt reduction in kidney function (KDIGO: creatinine increase =26.5 umol/L in 48h, or =1.5x baseline, or urine output <0.5 mL/kg/hr for 6h). Classified Stage 1-3 by severity. Causes: pre-renal (most common, hypoperfusion), intrinsic (ATN, AIN, GN), post-renal (obstruction). Management: treat the cause, optimise haemodynamics, avoid nephrotoxins. RRT indications: AEIOU (Acidosis, Electrolyte, Ingestion, Overload, Uraemia). Timing: STARRT-AKI (2020): no benefit of early RRT. CRRT preferred in haemodynamically unstable.
Checked against its sources on 3 Sept 2026
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Red flags
- STARRT-AKI (NEJM 2020): early initiation of RRT does NOT improve survival — wait for definitive indication unless urgent
- Hyperkalaemia (K+ >6.5 with ECG changes) is a medical emergency — calcium gluconate first, then insulin/dextrose, then RRT if refractory
- Avoid nephrotoxins: NSAIDs, ACE inhibitors, aminoglycosides, contrast, vancomycin — each dose in AKI worsens the injury
- Citrate anticoagulation for CRRT is preferred over heparin — lower bleeding risk, but monitor for calcium accumulation and metabolic alkalosis
Meet the patient
A 68-year-old with urosepsis is on day three in ICU. Her creatinine has tripled from 90 to 340 umol/L, she has made 120 mL of urine in twelve hours, and the blood gas shows potassium 6.8 mmol/L with peaked T waves and a widened QRS. The registrar reaches for the CRRT order form 'to stay ahead of the curve'.[20]
Two questions will decide her next hour — the two that decide every AKI: is there an indication to dialyse? (AEIOU answers that) and what stopped the kidney working? (the pre-renal, intrinsic, post-renal split answers that). Hold those two and the disease arranges itself.[1]
References27ShowHide
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