Practical issues of regional anticoagulation during continuous renal replacement therapy

Introduction: Extracorporeal blood purification techniques have become a well-established part of routine practice in intensive care units. The issue of major concern while applying these techniques is to ensure appropriate anticoagulation to prevent the clotting of the circuit. Aim: The aim of this paper is to present regional anticoagulation as a method which is currently used in continuous extracorporeal blood purification techniques. Material and methods: This work is based on the available literature and the authors’ experience. Results and discussion: Anticoagulation used to prevent the clotting of the circuit in extracorporeal blood purification techniques may be regional or systemic. Regional anticoagulation inhibits clotting only in the extracorporeal circuit. In this case either sodium citrate together with calcium substitution or heparin with protamine sulfate is used. Systemic anticoagulation involves the inhibition of clotting in the extracorporeal circuit and in the patient’s body. Regional citrate anticoagulation (RCA) is obtained with the use of citrate. With this technique calcium substitution is necessary in order to prevent hypocalcemia. Other possible complications include alkalosis, metabolic acidosis, hypercalcemia and hypomagnesemia. This paper presents also some practical aspects of regional anticoagulation during continuous renal replacement therapy (CRRT) Conclusions: The application of RCA has contributed to a wider use of CRRT in intensive therapy units. The greatest advantage of this method is almost complete elimination of bleeding complications associated with the therapy. It enables effective blood purification in the patients in whom the use of heparins is contraindicated. This fact has found confirmation in Kidney Disease: Improving Global Outcomes (KDIGO) guidelines.

Albumin Loss and Citrate Load in Pre-Dilution High Cut-Off-CVVHDF with Regional Citrate (18 mmol/L) and High Cut-Off CVVHD with Systemic Heparin: An in vitro Study

Background: Convective therapies with high cut-off membranes (HCO) are usually not recommended because of theoretical excessive albumin loss. The aim of this in vitro study is to demonstrate the noninferior safety of pre-dilution hemodiafiltration with HCO (HCO-CVVHDF) with isotonic citrate anticoagulation (18 mmol/L) with respect to heparin anticoagulated hemodialysis with HCO (HCO-CVVHD) in terms of albumin removal and citrate load. Method: ­Albumin removal was compared in vitro between 3 pre-­dilution-HCO-CVVHDF with citrate anticoagulation and 3 ­HCO-CVVHD with heparin anticoagulation during 30-min single-pass and 180-min recirculation phases. Results: Considering concentrations and flows in the extracorporeal circuit, the transmembrane albumin removal was 2.06 (1.51; 2.09) g and 2.09 (1.9; 2.8) g respectively for HCO-CVVHDF and HCO-CVVHD, during the single-pass phase; 2.8 (2.67; 4.59) g and 2.54 (2.35; 4.67) g, respectively, for HCO-CVVHDF and HCO-CVVHD during the recirculation phase. Based on the citrate saturation coefficients, a citrate metabolic load of 8.86 mmol/h has been calculated for HCO-CVVHDF. Conclusion: HCO-CVVHDF performed with regional anticoagulation with 18 mmol/L citrate solution does not induce higher ­albumin transmembrane removal compared to HCO-CVVHD.

Chloride content of solutions used for regional citrate anticoagulation might be responsible for blunting correction of metabolic acidosis during continuous veno-venous hemofiltration

Background Citrate, the currently preferred anticoagulant for continuous veno-venous hemofiltration (CVVH), may influence acid-base equilibrium. Methods The effect of 2 different citrate solutions on acid-base status was assessed according to the Stewart-Figge approach in two consecutive cohorts of critically ill adult patients. The first group received Prismocitrate 10/2 (PC10/2; 10 mmol citrate/L). The next group was treated with Prismocitrate 18/0 (PC18; 18 mmol citrate/L). Both groups received bicarbonate-buffered fluids in post-dilution. Results At similar citrate flow, the metabolic acidosis present at baseline in both groups was significantly attenuated in PC18 patients but persisted in PC10/2 patients after 24 h of treatment (median pH 7,42 vs 7,28; p = 0.0001). Acidosis in the PC10/2 group was associated with a decreased strong ion difference and an increased strong ion gap (respectively 43 vs. 51 mmol/L and 17 vs. 12 mmol/L, PC10/2 vs. PC18; both p = 0.001). Chloride flow was higher in PC10/2 than in PC18 subjects (25.9 vs 14.3 mmol/L blood; p < 0.05). Conclusion Correction of acidosis was blunted in patients who received 10 mmol citrate/L as regional anticoagulation during CVVH. This could be explained by differences in chloride flow between the applied citrate solutions inducing hyperchloremic acidosis.