0391-3988/418-07 $25.00/0 The International Journal of Artificial Organs / Vol. 31 / no. 5, 2008 / pp. 418-424 Regional citrate anticoagulation for hemodialysis: calcium-free vs. calcium containing dialysate - A randomized trial J. BUTUROVIC-PONIKVAR, S. CERNE, J. GUBENSEK, R. PONIKVAR Center for Dialysis, Department of Nephrology, University Medical Center Ljubljana, Ljubljana - Slovenia © Wichtig Editore, 2008 ABSTRACT: Background: The majority of citrate protocols for hemodialysis (HD) use calcium (Ca)- free dialysate, a limited number use dialysate with Ca, aiming to simplify the procedure. This ran- domized clinical study sought to compare the anticoagulant effect of citrate using Ca-free dialysate and dialysate with Ca 1.25 mmol/L. Methods: Fifty HD procedures (in 5 chronic HD patients treated by chronic citrate anticoagulation) were randomly assigned to Ca-free dialysate (25 procedures) or Ca-1.25 dialysate (25 procedures), both with Mg 0.5 mmol/L, Na 138 mmol/L, and bicarbonate 28 mmol/L. Ca-free HD: 15% Na 3 citrate 80 ml/hour was infused into the arterial line, and 1 M CaCl 2 , 14 ml/hour into the venous line. Ca-1.25 group: 15% Na 3 citrate 100 ml/hour, 1 M CaCl2 2-4 ml/hour. Polyflux H dialyzers were used. An- tithrombotic effect was assessed visually after HD at 3 points: dialyzer, arterial, and venous bubble traps, using a score of 5 (no clotting) to 1 (total clotting). Results: Ca-free group: arterial bubble trap score 4.7 ± 0.5, dialyzer 4.5 ± 0.6, venous bubble trap 4.8 ± 0.6. Ionized calcium (iCa) at dialyzer inlet 0.34 ± 0.17, outlet 0.21 ± 0.06 mmol/L. All HDs were completed successfully. Ca-1.25 group: arterial bubble trap score 4.7 ± 0.5 (NS), dialyzer 2.6 ± 1.04 (p<0.01), venous bubble trap 2.4 ± 0.9 (p<0.01). Volume of clot in venous bubble trap was 1.9 ± 1.8 mL (range 0.5-6 mL). iCa at dialyzer inlet 0.24 ± 0.05 mmol/L (p<0.05), outlet 0.63 ± 0.11 mmol/L (p<0.01). Four of 25 HD procedures (16%) were prematurely terminated due to threatening dialyzer clotting, in 6/25 HD procedures (24%), the venous line was changed (p<0.01). Conclusion: Citrate anticoagulation with Ca-1.25 dialysate resulted in significantly worse anticoagu- lation of dialyzer and venous bubble trap compared with Ca-free dialysate, despite higher citrate dose. (Int J Artif Organs 2008; 31: 418-24) KEY WORDS: Anticoagulation, Citrate, Hemodialysis, Metabolic alkalosis, Regional citrate anti- coagulation INTRODUCTION Citrate has many characteristics of the ideal anticoagu- lant for hemodialysis. Its anticoagulant effect is excellent and is limited to the dialysis circuit, without causing sys- temic anticoagulation. In addition to inhibiting coagula- tion, it reduces platelet deposition on the dialyzer mem- brane (1). By the decreased activation of platelets and coagulation, citrate anticoagulation may also increase the dialysis dose delivered. By chelating calcium (Ca) and magnesium, citrate reduces some of the effects of blood interaction with the dialyzer membrane (2-4), which are Ca- and magnesium-dependent, thus improving biocom- patibility of dialysis circuit. Using citrate, we avoid he- parin-induced thrombocytopenia, the condition that is in- creasingly recognized especially in intensive care units. Citrate is easily dialyzable (molecular weight of trisodium citrate is 294 Da), with an extraction coefficient of 70% or Artificial Kidney and Dialysis