Background: Regional citrate anticoagulation (RCA) is the recommended standard for continuous renal replacement therapy (CRRT). This study assesses its efficacy in patients admitted to critical care following cardiovascular surgery and the influence of standard antithrombotic agents routinely used in this specific group. Methods: Consecutive cardiovascular surgery patients treated with post-dilution hemofiltration with RCA were included in this prospective observational study. The primary outcome of the study was CRRT circuit life-span adjusted for reasons other than clotting. The secondary outcome evaluated the influence of standard antithrombotic agents (acetylsalicylic acid [ASA], low molecular weight heparin [LMWH] or fondaparinux as thromboprophylaxis or treatment dose with or without ASA) on filter life. Results: Fifty-two patients underwent 193 sessions of CVVH, after exclusion of 15 sessions where unfractionated heparin was administered. The median filter life span was 58 hours. Filter life span was significantly longer in patients receiving therapeutic dose of LMWH or fondaparinux (79 h [2-110]), in comparison to patients treated with prophylactic dose of LMWH or fondaparinux (51 h [7-117], p < 0.001), and patients without antithrombotic prophylaxis (42 h [2-91], p < 0.0001). 12 bleeding episodes were observed; 8 occurred in patients receiving treatment dose anticoagulation, 3 in patients receiving prophylactic dose anticoagulation and 1 in a patient with no antithrombotic prophylaxis. Conclusions:A post dilution hemofiltration with RCA provides prolonged filter life span when adjusted for reasons other than clotting. Patients receiving treatment dose anticoagulation had a significantly longer filter life span than those who were on prophylactic doses or ASA alone.

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Background: Patients with known or new-onset acute renal failure after cardiovascular surgery, requiring renal replacement therapy, can benefit from adequate non-heparin circuit anticoagulation. The idea behind not using heparin relates to the post-operative risk of bleeding. Simplified regional citrate anticoagulation (RCA) protocol proposes the use of citric acid dextrose formula A (ACD-A) during post-dilutional continuous veno-venous hemofiltration (CVVH) with standard bicarbonate buffered calcium containing replacement solution. Citrate accumulation diagnosed upon total to ionized calcium ratio (tCa/iCa) and low ionized calcium (iCa) are considered as the biggest risks related to regional citrate accumulation.Methods: This prospective observational study evaluated electrolyte and acid-base homeostasis in cardiovascular surgery patients with known chronic or new-onset acute renal failure treated with post-dilution continuous veno-venous haemofiltration (CVVH) with a simplified RCA protocol with ACD-A. In total, 50 consecutive cardiovascular surgery patients treated with CVVH with RCA were evaluated. Base excess; pH; bicarbonate, lactate, Na+, Cl-, Mg++, and inorganic phosphate concentrations; the total to ionized calcium ratio (tCa/iCa); and high anion gap metabolic acidosis were assessed during haemofiltration treatment in survivors and non-survivors.Results: Thirty-three (66%) patients died. In total, 235 haemofiltration sessions with a median circuit survival time of 57 hours (1-117) were evaluated. The therapies were very well balanced with regard to sodium and chloride homeostasis. The lactate concentration and anion gap decreased during CVVH sessions longer than 72 hours, but no inter-group difference was observed. The tCa/iCa ratio exceeded 2.5 in 11 of 246 (4.5%) readings and was significantly higher in non-survivors (p=0.037). No correlation was observed between the lactate concentration before haemofiltration and the tCa/iCa ratio during haemofiltration. Magnesium and phosphate concentrations decreased during CVVH, and additional supplementation with magnesium was necessary. The magnesium concentration was lower in the non-survivors.Conclusions: The CVVH RCA protocol provides stable sodium and chloride concentrations and a tendency towards higher pH values and bicarbonate concentrations. Supplementation with magnesium and phosphate ions is needed. The incidence of citrate accumulation exceeded 4% and was significantly higher in non-survivors.Trial registration: retrospectively registered: Clinicaltrials.gov, NCT03836742.

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Background: Patients after cardiovascular surgery, requiring renal replacement therapy, can benefit from adequate non-heparin circuit anticoagulation. Simplified regional citrate anticoagulation (RCA) protocol proposes the use of citric acid dextrose formula A (ACD-A) during post-dilutional continuous veno-venous hemofiltration (CVVH) with standard bicarbonate buffered calcium containing replacement solution. Citrate accumulation diagnosed upon total to ionized calcium ratio (tCa/iCa) and low ionized calcium (iCa) are considered as the biggest risks related to regional citrate accumulation. Methods: This prospective observational case-control study evaluated electrolyte and acid-base homeostasis in cardiovascular surgery patients treated with post-dilution CVVH with a simplified RCA protocol with ACD-A. In total, 50 consecutive cardiovascular surgery patients were evaluated. Base excess, pH, bicarbonate, lactate, Na+, Cl-, Mg++, and inorganic phosphate concentrations, the total to ionized calcium ratio (tCa/iCa), and high anion gap metabolic acidosis were assessed during haemofiltration treatment in survivors and non-survivors. Results: Thirty-three (66%) patients died. The therapies were very well balanced in sodium and chloride homeostasis. The lactate concentration and anion gap decreased during CVVH sessions lasting longer than 72 hours, but no inter-group difference was observed. The tCa/iCa ratio exceeded 4.5% and was significantly higher in non-survivors (p=0.037). Initial lactate concentration did not correlate with tCa/iCa ratio during haemofiltration. Magnesium and phosphate concentrations decreased and additional supplementation with magnesium was necessary. The magnesium concentration was lower in the non-survivors. Conclusions: The incidence of citrate accumulation exceeded 4% and was significantly higher in non-survivors. Supplementation with magnesium and phosphate ions is needed in CVVH with RCA.