Renal & Electrolytes

CRRT Effluent Dose (mL/kg/h) Calculator

Total effluent rate per kg per hour, with a predilution correction, against the KDIGO target of 20–25 mL/kg/h delivered.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

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Formula

Effluent (mL/h) = dialysate + replacement (pre- and post-filter) + pre-blood-pump fluid + net patient fluid removal
Dose (mL/kg/h) = effluent ÷ weight
Predilution correction: dose × Qb ÷ (Qb + pre-filter fluid), with blood flow Qb in mL/h (mL/min × 60)
Example: 80 kg, dialysate 1,000, pre-filter 500, post-filter 500, removal 100 mL/h: effluent 2,100 mL/h = 26.3 mL/kg/h; at Qb 200 mL/min (12,000 mL/h), × 12,000 ÷ 12,500 = 25.2

How it is used

• KDIGO recommends delivering an effluent volume of 20–25 mL/kg/h for CRRT in AKI (1A); because delivered dose usually falls short of the prescription, this generally means prescribing 25–30 and keeping interruptions short (KDIGO 2012).
• Higher doses did not help: ATN compared 20 with 35 mL/kg/h and RENAL 25 with 40 mL/kg/h, with no difference in mortality; RENAL saw more hypophosphatemia at the higher dose (KDIGO 2012).
• Effluent overstates the dose with predilution, interruptions and a clogging membrane; check delivered against prescribed dose often and adjust (KDIGO 2012; Neri 2016).

Key points

• Record every minute of downtime (bag changes, filter clotting, CT trips): the delivered dose is the prescribed dose minus that time.

Same formula as the app. Open it in the web app.

Related one-pagers

• CRRT (Continuous Renal Replacement)KDIGO: deliver 20–25 mL/kg/h
• Electrolyte ImbalancesChronic SIADH: restrict fluid first; restriction cannot work when urine Na + K exceeds serum Na (Furst 2000). Second line (Europe 2014): urea 0.25–0.50 g/kg/day or a loop diuretic with oral salt. Tolvaptan starts in hospital, with no fluid restriction for 24 h, for at most 30 days (label: liver injury); Europe advises against vaptans. Hypovolemia: 0.9% saline or balanced fluid at 0.5–1 mL/kg/h (Europe 2014).
• BurnsAdult · 0.5 mL/kg/h (about 30 to 50 mL/h)
• Acute Kidney Injury1 · 1.5–1.9 × baseline, or up ≥0.3 mg/dL · <0.5 mL/kg/h for 6–12 h

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For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.