Citrate anticoagulation during CVVH in high risk bleeding patients

Background: Regional citrate anticoagulation (RCA) is an effective form of anticoagulation for continuous renal replacement therapy (CRRT) in patients with contraindications to heparin. Its use has been very limited, possibly because of the need for special infusion solutions and difficult monitoring of the metabolic effects. Objective: To investigate the safety and the feasibility of an RCA method for continuous veno-venous hemofiltration (CVVH) using commercially available replacement fluid. Methods: We evaluated 11 patients at high risk of bleeding, requiring CVVH. RCA was performed using commercially available replacement fluid solutions to maintain adequate acid-base balance. We adjusted the rate of citrate infusion to achieve a post-filter ionized calcium concentration [iCa] < 0.4 mmol/L when blood flow was < 250 ml/min, or < 0.6 mmol/L when blood flow was > 250 ml/min. When needed, we infused calcium gluconate to maintain systemic plasma [iCa] within the normal range. Results: Twenty-nine filters ran for a total of 965.5 h. Average filter life was 33.6 +/- 20.5 h. Asymptomatic hypocalcemia was detected in 6.9% of all samples. No [iCa] values < 0.9 mmol/L were observed. Hypercalcemia (1.39 +/- 0.05 mmol/L) occurred in 2.5% of all samples. We observed hypematremia (threshold 153 mmol/L) and alkalosis (threshold 7.51) in only 9.3% and 9.4% respectively of all samples, mostly concomitantly. No patient showed any signs of citrate toxicity. Conclusions: We developed a protocol for RCA during CVVH using commercially available replacement fluid that proved safe, flexible and applicable in an Intensive Care Unit (ICU) setting.