Continuous Renal Replacement Therapy (CRRT) — Comprehensive ICU Management

Also known as CRRT · CVVH · CVVHD · CVVHDF · Continuous venovenous haemofiltration · Regional citrate anticoagulation · AKIKI trial · STARRT-AKI trial

CRRT (continuous renal replacement therapy) — the renal support modality for haemodynamically unstable ICU patients. Three modalities: CVVH (continuous venovenous haemofiltration — predominantly convective clearance), CVVHD (continuous venovenous haemodialysis — predominantly diffusive clearance), CVVHDF (continuous venovenous haemodiafiltration — combines dialysis and haemofiltration). Anticoagulation: REGIONAL CITRATE — KDIGO recommends citrate over unfractionated heparin in patients without contraindications, with or without increased bleeding risk; citrate chelates ionised calcium in the circuit, a separate calcium infusion replaces systemic losses, and the total-to-ionised calcium ratio is the sentinel for citrate accumulation (albumin-corrected ratio 2.5 or above defines accumulation; ratio 2.4 or above independently predicts 28-day mortality). Effluent dose: guidelines recommend a prescribed dose of 20 to 25 mL per kg per hour; RENAL (25 vs 40 mL/kg/h) and ATN (20 vs 35 mL/kg/h) showed no survival benefit from higher intensity. Timing: AKIKI and STARRT-AKI showed no mortality benefit from early or accelerated initiation.

high47 referencesUpdated 1 Sept 202628 min readSource-verified · Sept 2026

Checked against its sources on 1 Sept 2026

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CRRT is the renal replacement modality for the haemodynamically unstable ICU patient — three techniques that differ in their mode of solute clearance: CVVH is predominantly convective, CVVHD predominantly diffusive, and CVVHDF combines dialysis and haemofiltration.^[21] Regional citrate is the recommended anticoagulant — KDIGO recommends citrate rather than unfractionated heparin in patients without contraindications, with or without increased bleeding risk, and the total-to-ionised calcium ratio is the sentinel that tells you whether the liver is keeping up (an albumin-corrected ratio of 2.5 or above defines citrate accumulation).^[7]^[11] Prescribe an effluent dose of 20 to 25 mL per kg per hour — current guidelines recommend exactly that, and RENAL (25 versus 40) and ATN (20 versus 35) found no survival benefit from higher intensity. Remember that AKIKI and STARRT-AKI killed the "start early" reflex — wait for an urgent indication, because a delayed strategy averted dialysis in 49 per cent of AKIKI's deferred patients.^[5]^[3]^[4]^[1]^[2]

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