Module 18 · Renal, fluids & metabolic

Renal replacement therapy

NewPhase 2

Renal replacement therapy in the ICU: when to start (AEIOU, STARRT-AKI, AKIKI 2), choosing CRRT, IHD or SLED, writing a CRRT prescription, citrate vs heparin, troubleshooting circuits, and antibiotic dosing on CRRT.

6 topics

Drugs in this module

Doses written for this module's context. The same drug may read differently in another module.

Trisodium citrate (regional citrate anticoagulation)

Regional anticoagulant (chelates calcium)

Indications
First-line CRRT anticoagulation (KDIGO) in patients without contraindication
Adult dose
Pre-filter citrate (e.g. 4% trisodium citrate or citrate-containing replacement fluid) dosed to achieve post-filter ionised Ca 0.25-0.35 mmol/L; systemic calcium chloride/gluconate infusion post-filter to keep patient ionised Ca 1.0-1.2 mmol/L.
Preparation (India)
Commercial citrate solutions (e.g. 4% trisodium citrate, Prismocitrate/Regiocit) - availability limited in India; machine-specific protocols.
Cautions
Citrate accumulation in liver failure, severe lactic acidosis (lactate > 4 mmol/L) or severe shock: high anion gap acidosis, total/ionised Ca ratio > 2.5. Metabolic alkalosis and hypernatraemia with excessive citrate.
Monitoring
Post-filter and systemic iCa at 1 h, then 6-hourly; total Ca daily; ABG, Na, Mg.

Unfractionated heparin (CRRT circuit)

Anticoagulant

Indications
CRRT circuit anticoagulation when citrate is unavailable or contraindicated
Adult dose
Optional priming; pre-filter infusion 5-10 units/kg/h (typically 300-1,000 units/h), titrated to aPTT 45-60 s (≈ 1.5x control) or per local protocol.
Preparation (India)
25,000 units in 50 mL NS = 500 units/mL (or 5,000 units in 50 mL = 100 units/mL for low-dose circuit use).
Cautions
Bleeding, HIT (switch to citrate/argatroban). Avoid if active bleeding or platelets < 50 x10^9/L.
Monitoring
aPTT 6-hourly initially, platelets daily.

Meropenem

Carbapenem

Indications
Severe hospital-acquired / ESBL infections
Adult dose
CRRT (effluent 20-25 mL/kg/h): 1 g q8h (2 g q8h for CNS or high MIC). IHD: 500 mg-1 g q24h, dose after dialysis. SLED: 1 g q12h (after session).
Preparation (India)
500 mg and 1 g vials; extended infusion over 3 h.

Piperacillin-tazobactam

Antipseudomonal penicillin + beta-lactamase inhibitor

Indications
Hospital-acquired infections
Adult dose
CRRT: 4.5 g q8h (or 3.375 g q6h); extended infusion. IHD: 2.25 g q8-12h + dose after dialysis.
Preparation (India)
4.5 g vials.

Vancomycin

Glycopeptide

Indications
MRSA infections
Adult dose
Load 20-25 mg/kg (actual body weight) for all; CRRT maintenance ~15 mg/kg q24h (or 7.5-10 mg/kg q12h) guided by levels (trough 15-20 mg/L or AUC 400-600). IHD: 15-25 mg/kg load, then 500-1,000 mg after each session by pre-dialysis levels.
Preparation (India)
500 mg and 1 g vials; infuse ≤ 10 mg/min.

Colistin (colistimethate sodium)

Polymyxin

Indications
CRE/MDR gram-negative infections
Adult dose
Load 300 mg colistin base activity (CBA) = 9 million units. CRRT: maintenance ~220-440 mg CBA/day in divided doses (international consensus suggests higher doses due to clearance). IHD: daily dose on non-dialysis days + supplemental dose after dialysis.
Preparation (India)
1 million and 2 million unit vials (1 million units ≈ 33 mg CBA).
Cautions
Nephrotoxicity, neurotoxicity; dose labelling confusion (units vs mg CBA vs mg CMS).

Module references (10)

  1. 1

    Kidney Disease: Improving Global Outcomes (KDIGO) AKI Work Group. KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl 2012;2:1-138 (summary: Nephron Clin Pract 2012;120:c179-84).

  2. 2

    STARRT-AKI Investigators. Timing of initiation of renal-replacement therapy in acute kidney injury. N Engl J Med 2020;383:240-51.

  3. 3

    Gaudry S, Hajage D, Schortgen F, et al. Initiation strategies for renal-replacement therapy in the intensive care unit (AKIKI). N Engl J Med 2016;375:122-33.

  4. 4

    Gaudry S, Hajage D, Martin-Lefevre L, et al. Comparison of two delayed strategies for renal replacement therapy initiation for severe acute kidney injury (AKIKI 2). Lancet 2021;397:1293-300.

  5. 5

    Zarbock A, Kellum JA, Schmidt C, et al. Effect of early vs delayed initiation of renal replacement therapy on mortality in critically ill patients with acute kidney injury: the ELAIN randomized clinical trial. JAMA 2016;315:2190-9.

  6. 6

    RENAL Replacement Therapy Study Investigators. Intensity of continuous renal-replacement therapy in critically ill patients. N Engl J Med 2009;361:1627-38.

  7. 7

    VA/NIH Acute Renal Failure Trial Network. Intensity of renal support in critically ill patients with acute kidney injury. N Engl J Med 2008;359:7-20.

  8. 8

    Zarbock A, Kullmar M, Kindgen-Milles D, et al. Effect of regional citrate anticoagulation vs systemic heparin anticoagulation during continuous kidney replacement therapy on dialysis filter life span and mortality (RICH). JAMA 2020;324:1629-39.

  9. 9

    Hoff BM, Maker JH, Dager WE, Heintz BH. Antibiotic dosing for critically ill adult patients receiving intermittent hemodialysis, prolonged intermittent renal replacement therapy, and continuous renal replacement therapy: an update. Ann Pharmacother 2020;54:43-55.

  10. 10

    Ostermann M, Joannidis M, Pani A, et al. Patient selection and timing of continuous renal replacement therapy (ADQI 17). Blood Purif 2016;42:224-37.