Skip to main content

Regional citrate anticoagulation in CVVH: a new protocol combining citrate solution with a phosphate-containing replacement fluid


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.

Author information

Authors and Affiliations


Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Cite this article

Morabito, S., Pistolesi, V., Tritapepe, L. et al. Regional citrate anticoagulation in CVVH: a new protocol combining citrate solution with a phosphate-containing replacement fluid. Crit Care 16, P366 (2012).

Download citation

  • Published:

  • DOI:


  • HCO3
  • Serum Phosphate
  • Hypophosphatemia
  • Citr Solution
  • Citr Concentration