How to manage icodextrin levels when on Continuous Renal Replacement Therapy (CRRT)?

Managing Ionized Calcium (iCal) Levels During CRRT

Critical Understanding: Citrate Anticoagulation and Calcium

Regional citrate anticoagulation during CRRT chelates calcium in the extracorporeal circuit, requiring systematic calcium replacement and monitoring to prevent life-threatening hypocalcemia. 1

Preferred Anticoagulation Strategy

• Regional citrate anticoagulation is recommended over heparin for CRRT in patients without citrate contraindications (Grade 2B). 1
• Citrate provides superior circuit longevity while minimizing systemic anticoagulation effects 1
• In patients with increased bleeding risk, citrate remains preferred over no anticoagulation (Grade 2C) 1

Citrate Contraindications Requiring Alternative Approaches

• Severe liver failure (inability to metabolize citrate to bicarbonate) 1
• Shock states with tissue hypoperfusion and lactic acidemia 2
• Citrate accumulation risk (citrate/ionized calcium ratio >2.5) 1

Calcium Monitoring Protocol During Citrate CRRT

Monitor ionized calcium levels every 4-6 hours initially, then every 6-12 hours once stable: 3, 4

• Systemic (post-filter) ionized calcium target: 1.0-1.2 mmol/L 1
• Circuit (pre-filter) ionized calcium target: 0.25-0.35 mmol/L (ensures adequate anticoagulation) 1
• Measure both pre-filter and post-filter iCal to assess citrate efficacy and patient safety 1

Calcium Replacement Strategy

Administer calcium chloride or calcium gluconate via separate central venous access (never through the CRRT circuit): 1

• Starting calcium infusion rate: 1-2 grams calcium chloride per hour (adjust based on iCal levels) 1
• Calcium replacement rate typically equals 60-80% of citrate infusion rate 1
• Use calcium chloride preferentially (provides 3x more elemental calcium than gluconate per gram) 1

Signs of Citrate Accumulation and Toxicity

Monitor for widening gap between total and ionized calcium (>2.5 mmol/L suggests citrate accumulation): 1

• Progressive metabolic acidosis despite bicarbonate generation 1
• Hypocalcemia refractory to calcium replacement 1
• Hemodynamic instability, arrhythmias, or altered mental status 1

Alternative Anticoagulation When Citrate Contraindicated

• Use unfractionated heparin or low-molecular-weight heparin (Grade 2C) 1
• In heparin-induced thrombocytopenia: use argatroban (0.7-1.7 µg/kg/min) or Factor Xa inhibitors (Grade 1A) 1
• No anticoagulation is acceptable in high bleeding risk patients, though circuit life decreases 1

CRRT Prescription Considerations Affecting Calcium

• Deliver effluent volume of 20-25 mL/kg/h (Grade 1A) 1, 2
• Use bicarbonate-based replacement fluids when available (preferred over lactate, especially in shock/liver failure) 1, 2
• Prescribe 20-25% higher than target dose to account for downtime and circuit issues 2, 3

Common Pitfalls to Avoid

• Never infuse calcium through the CRRT circuit (causes immediate circuit clotting) 1
• Avoid citrate in patients with lactate >5 mmol/L or severe liver dysfunction 1, 2
• Do not rely on total calcium alone—ionized calcium is the physiologically active form requiring monitoring 1
• Recognize that hypomagnesemia and hypokalemia commonly develop during CRRT and require concurrent monitoring 4