Predilution Solutions to Reduce Clotting in CRRT
Regional citrate anticoagulation is the recommended first-line approach to reduce clotting in CRRT for patients without contraindications to citrate. 1
Anticoagulation Options for CRRT
First-Line Approach
- Regional citrate anticoagulation is superior to other methods for preventing circuit clotting in CRRT when there are no contraindications 1, 2
- Citrate works by chelating calcium in the extracorporeal circuit, inhibiting the coagulation cascade 2
- This approach provides regional anticoagulation without increasing systemic bleeding risk 1
Alternative Approaches
- For patients with contraindications to citrate (severe liver dysfunction), unfractionated or low-molecular-weight heparin can be used 1
- In patients with high bleeding risk, running CRRT without anticoagulation is preferable to using heparin 1
- For patients with heparin-induced thrombocytopenia (HIT), direct thrombin inhibitors (argatroban) or Factor Xa inhibitors (danaparoid, fondaparinux) should be used 1
CRRT Modality Considerations
- CVVHD (Continuous Venovenous Hemodialysis) provides greater solute clearance than CVVH at equivalent flow rates 3
- Predilution CVVH has approximately 15% lower clearance of small molecules compared to postdilution CVVH or CVVHD 3
- At low blood flow rates typically used in pediatric patients, CVVHD appears optimal for maximizing clearance while minimizing filter clotting 3
Optimizing Circuit Patency Through Technical Adjustments
- Use partial predilution in convective modes (CVVH) to reduce hemoconcentration and extend filter life 4
- Individualize control of filtration fraction to prevent excessive hemoconcentration 4
- Optimize catheter position and size (larger inner diameter catheters in right internal jugular vein preferred) 4, 5
- Maintain appropriate blood flow rates (typically 100-150 mL/min for CVVHDF) 6
Fluid Composition Recommendations
- Use bicarbonate-buffered solutions rather than lactate-buffered solutions for dialysate and replacement fluid 6
- Dialysate or substitution fluid should contain physiologic concentrations of electrolytes 6
- Avoid fluids with supra-physiologic glucose concentrations 6
- Consider using dialysis solutions containing potassium, phosphate, and magnesium to prevent electrolyte disorders 2
Monitoring Requirements
- During citrate anticoagulation, frequently measure post-filter and systemic ionized calcium to titrate citrate and calcium replacement 6, 2
- Monitor acid-base balance regularly, particularly in patients at risk for citrate accumulation 2
- Track serum sodium levels to prevent hypernatremia with citrate anticoagulation 2
- Monitor for electrolyte abnormalities including hypophosphatemia, hypokalemia, and hypomagnesemia 2
Special Considerations
- Implement strict protocols for citrate anticoagulation with adequate staff education 2
- Delivered effluent dose should target 20-25 mL/kg/h with prescription of 25-30 mL/kg/h to account for treatment interruptions 6
- For patients with liver dysfunction receiving citrate, closely monitor for signs of citrate accumulation 2
By implementing these evidence-based approaches to anticoagulation and optimizing CRRT settings, circuit patency can be maximized while minimizing complications related to clotting and bleeding.