Introduction. Regional citrate anticoagulation (RCA) is increasingly used in CRRT, especially in high bleeding risk patients (pts). Regardless of anticoagulation (AC) protocol, hypophosphatemia occurs frequently in CRRT. The aim was to evaluate safety and effects on acid-base (A-B) balance and phosphatemia of a new RCA-CVVH protocol using a 18 mmol/L citrate solution (Citr) combined with a phosphate-containing replacement solution (sol).

Methods. In pts with AKI following cardiac surgery, RCA-CVVH was performed using a 18 mmol/L Citr (Prismocitrate 18/0) and a recently introduced phosphate-containing post-dilution sol with bicarbonate (30 mEq/L) and calcium (1.25 mmol/L) (Phoxilium). In relation to blood flow rate (Qb), Citr rate was set to meet a circuit (circ) citrate concentration of 2.5 mmol/L, modified to obtain circ-Ca++ <0.5 mmol/L. CaCl2 (10%) was infused to maintain systemic Ca++ (s-Ca++) 1.1-1.25 mmol/L.

Results. In a period of 7 months, 10 pts at high bleeding risk (age 71.8±11.7, SOFA 14.71±2.5) underwent RCA-CVVH using the new protocol. Initial settings: Qb 140 mL/min; Q Citr 910±31.6 mL/h; Q post-dilution 1190±31.6 mL/h; estimated Citr load 9.7±0.5 mmol/h; CaCl2 1.7±0.3 mL/h. Twenty-five RCA-CVVH circ were used with filter life 46.8±30.3 h (median 43; total 1170). RCA stopping causes: 56% scheduled, 24% CVC malfunction, 8% clotting, 8% medical procedures, 4% alarm handling/technical issues. No pts had metabolic or bleeding complications (transfusion rate 0.29/day). Patient’s A-B status and electrolytes: pH 7.43±0.04, HCO3- 24.3±1.8 mmol/L, BE -0.3±2.4, s-Ca++ 1.13±0.11 mmol/L (CaCl2 infusion 2.2±0.9 mmol/h), phosphate 3.5±1.2 mg/dL without additional supplementation needs, K+ 4.3±0.3 mmol/L (KCl infusion 2.5±2.5 mmol/h).

Conclusion. The new RCA-CVVH protocol allowed adequate filter survival in spite of a low citrate dose, a higher than usual target circuit Ca++ and a calcium-containing replacement solution. Furthermore, the protocol provided a optimal A-B balance and was able to prevent hypophosphatemia reducing the need for additional infusions. Finally, the use of uncustomized, conventional, CRRT solutions allowed to further reduce RCA-CVVH complexity minimizing the risk of errors related to bags handling.