Unapparent systemic effects of regional anticoagulation with citrate in continuous renal replacement therapy a narrative review

Abstract

After citrate administration, calcium citrate complexes are formed. Clearance in diffusive modes increases with the dialysate flow, in convective modes with filtration flow [12]. Complexes that are not removed through the hemofilter return to the patient. In convective modes up to 60% of the citrate given prefilter is cleared via the hemofilter into the effluent (sometimes more in diffusive modes), the rest returning to the patient for metabolization [12]. Decreasing blood flow limits the amount of delivered citrate to the extracorporeal circuit. Limiting blood flows in convective modes in combination with high filtration rates may lead to a high filtration fraction. Therefore, higher blood flows resulting in a higher delivered citrate dose may be necessary in convective modes, compared to diffusive modes, to achieve similar levels of clearance [4]. The Kidney Disease Improving Global Outcomes guidelines recommend targeting an effluent flow of 20–25 ml/kg/h [1]. Before the blood from the circuit is returned to the patient, calcium is added to normalize iCa and coagulation. Numerous protocols for regional citrate anticoagulation are available, utilizing different citrate solutions and CRRT modalities (continuous veno-venous hemofiltration (CVVH), continuous veno-venous hemodialysis (CVVHD), continuous veno-venous hemodiafiltration (CVVHDF)[4].