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- Open Access
Regional citrate anticoagulation in CVVH: a new protocol combining citrate solution with a phosphate-containing replacement fluid
© Morabito et al.; licensee BioMed Central Ltd. 2012
- Published: 20 March 2012
- Serum Phosphate
- Citr Solution
- Citr Concentration
Regional citrate anticoagulation (RCA) is a highly effective anticoagulation (AC) method in CRRT and different combinations of citrate (Citr) and CRRT solutions can affect the acid-base (A-B) balance. Regardless of the AC protocol, hypophosphatemia occurs frequently in CRRT (80%). The aim was to evaluate safety and effects on A-B balance of a new RCA-CVVH protocol using 18 mmol/l Citr solution combined with a phosphate-containing hemofiltration (HF) solution.
In our center, RCA-CVVH is routinely performed with a 12 mmol/l predilution Citr solution (Prismocitrate 10/2) and a postdilution HF solution (HCO3- 32, Ca2+ 1.75, Mg2+ 0.5, K+ 2 mmol/l) (protocol A). In the case of persistent acidosis, not related to Citr accumulation, NaHCO3 infusion is started. In order to optimize the buffer balance, a new protocol has been designed throughout a mathematical model developed to estimate Citr and HCO3- mass transfer. Recently introduced solutions have been adopted: 18 mmol/l predilution Citr solution (Prismocitrate 18), postdilution HF solution (Phoxilium, HCO3- 30, phosphate 1.2, Ca2+ 1.25, Mg2+ 0.6, K+ 4 mmol/l) (protocol B). In relation to Qb, the Citr solution rate was set to meet the target circuit Citr concentration (3 mmol/l). To maintain systemic Ca2+ (1.1 to 1.25 mmol/l), CaCl2 10% was started according to estimated Ca2+ loss.
In a cardiac surgery patient with AKI, A-B status and electrolytes have been evaluated comparing protocol A (five circuits, 301 hours) versus protocol B (two circuits, 97 hours): pH 7.39 ± 0.03 versus 7.44 ± 0.03 (P < 0.0001), blood HCO3- 22.3 ± 1.8 versus 22.6 ± 1.4 mmol/l (P = NS), BE -2.8 ± 2.1 versus -1.6 ± 1.2 (P < 0.01), serum phosphate 0.85 ± 0.2 versus 1.3 ± 0.5 mmol/l (P = 0.027), serum K+ 4 ± 0.2 versus 4.2 ± 0.3 mmol/l (P = NS) with KCl infusion 4 ± 0.2 versus 1.4 ± 1.5 mmol/hour (P < 0.0001). Protocol A required NaHCO3 and Na-phosphate infusion (8.9 ± 2.8 mmol/hour and 5 g/day, respectively) while protocol B allowed one to stop both supplementations. Systemic and circuit Ca2+ were easily maintained in the target range with both protocols.
Although needing confirmation in an adequate number of patients, protocol B was able to provide a buffer balance more positive than protocol A and allowed one to adequately control the A-B status without additional NaHCO3 infusion and in the absence of alkalosis, despite the use of a standard HCO3- concentration HF solution. Furthermore, the combination of a phosphate-containing replacement fluid appeared effective to prevent hypophosphatemia. Finally, the use of a mathematical model allowed predicting the effects of different replacement solutions and/or RCA-CVVH settings on the mass balance of the main solutes.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.