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CRRT Dose Prescription — CVVH/CVVHDF Protocol

Personalization of continuous renal replacement therapy dose, anticoagulation, and solution choice in the critically ill patient.

Written by: Saygı Hospital Health Guide Editorial Board
Published: · Last updated:

This content is for general information; please consult your physician for diagnosis and treatment.

References (3)

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What is CRRT Dose Prescription — CVVH/CVVHDF Protocol?

Continuous Renal Replacement Therapy (CRRT) is a 24-hour, continuous dialysis modality used for acute kidney injury (AKI) in hemodynamically unstable critically ill patients. Compared with intermittent hemodialysis, it provides slower fluid and solute removal and better hemodynamic tolerability.

Main modes — CVVH (Continuous Veno-Venous Hemofiltration — purely convective, with replacement fluid), CVVHD (purely diffusive, with dialysate), and CVVHDF (combined). Convective modes offer an advantage in clearing middle-molecular-weight uremic toxins.

Dose — the effluent dose (filtrate + dialysate flow) target is 20-25 mL/kg/hour. The ATN (2008) and RENAL (2009) trials showed no mortality difference between high-dose (>35 mL/kg/hour) and standard-dose CRRT. A 20-25% drop between prescribed and delivered dose (from filter clotting and interruptions) should be anticipated.

Anticoagulation — regional citrate anticoagulation (RCA) is recommended in the 2012 KDIGO guidelines (longer filter life, less bleeding, but requires monitoring for metabolic alkalosis and citrate accumulation). Alternatives: systemic heparin, argatroban (for HIT), or no anticoagulation (shorter filter life) in specific circumstances.

Symptoms

Hemodynamically unstable AKI — vasopressor requirement, intolerance of IHD, hypotension during intermittent HD
Oliguria with severe fluid overload (pulmonary edema; ARDS with critical fluid balance) that is diuretic-unresponsive
Life-threatening hyperkalemia (>6.5), metabolic acidosis (pH <7.15), or uremic symptoms (pericarditis, encephalopathy, bleeding)
Severe hyper-/hyponatremia, intoxication (lithium, methanol, ethylene glycol in selected cases)
Cytokine removal in sepsis — high-volume hemofiltration or adsorption cartridges (CytoSorb, oXiris) — evidence is limited

Risk Factors

Catheter-placement complications — pneumothorax, bleeding, arterial puncture, infection (CLABSI)
Anticoagulation — bleeding (heparin) versus citrate toxicity (total/ionized Ca ratio >2.5)
Hypothermia — the CRRT circuit causes heat loss; active warming is required
Electrolyte disturbances — hypophosphatemia (40-60%), hypomagnesemia, hypokalemia should be corrected with additives
Drug dosing — antibiotics (vancomycin, meropenem, piperacillin-tazobactam) are removed by CRRT; underdosing leads to treatment failure

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Hemodynamically unstable AKI at KDIGO stage 2-3 with an absolute indication (hyperkalemia, fluid overload, uremic symptoms)
  • Sepsis + AKI + vasopressor requirement — early CRRT decision (late initiation does not affect mortality per AKIKI/IDEAL-ICU)
  • Intermittent HD attempted but not hemodynamically tolerated — transition to CRRT

Treatment Methods

01
Catheter placement — a 13-14 French double-lumen central venous catheter (right jugular preferred; femoral acceptable; subclavian not recommended due to stenosis risk); ultrasound guidance mandatory
02
Mode selection — CVVHDF is the default in most centers (convective + diffusive, with the advantage of middle-molecular-weight clearance); CVVH may be selected for sepsis/cytokine removal
03
Dose calculation — effluent flow = 20-25 mL/kg/hour × body weight. For a 70-kg patient, ~1500 mL/hour. Post-dilution (replacement fluid after filter) is more effective but shortens filter life; pre-dilution is safer with ~15% dose loss
04
Anticoagulation — RCA preferred: citrate flow 3-4 mmol/L of blood pre-filter, post-filter ionized Ca 0.25-0.35, systemic Ca infusion targeting 0.45-0.55. Heparin alternative: 10-20 U/kg/hour with aPTT 1.5×
05
Solution selection — bicarbonate-based, electrolyte-balanced (sodium 140, potassium 2-4, calcium 1.5, magnesium 0.5, chloride 110, bicarbonate 32). Potassium and phosphate additives are titrated under clinical monitoring
06
Monitoring and dose adjustment — electrolytes, BUN, creatinine, ionized calcium (in RCA), magnesium, and phosphate twice daily. Adjust drug doses for CRRT clearance (vancomycin 15 mg/kg q24h, meropenem 1 g q12h, etc.). Target filter life 48-72 hours

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.