Citrate- Versus Acetate-Based Dialysate in Bicarbonate Haemodialysis: Consequences on Haemodynamics, Coagulation, Acid-Base Status and Electrolytes

Introduction:

A concentrate for bicarbonate haemodialysis acidified with citric instead of the less physiologic acetic acid has been successfully implemented in the United States in the past 7 years [1-3]. Contrarily to traditional regional citrate anticoagulation, the small amount of citrate used in the acid concentrate (0.8 mmol/L only; about one-fifth of the concentration necessary to achieve anticoagulation [1,4,5]) affects the calcium concentration and the locally enhanced coagulation activation in a limited way, resulting in approximately 10% reduction in post-dialysis ionized calcium and in no measurable systemic anticoagulation [1]. The absence of significant systemic repercussions is related to both, the low amount of citrate used but also the rapid conversion of citrate into bicarbonate taking place in the liver and muscles and determining a higher post-dialysis bicarbonataemia [1,6,7]. Despite the rapid citrate clearance, the local consequences of removing calcium from the blood clotting cascade has measurable positive effects on the dialyser life-span in the "reuse" modality and on the dialysis quality quantified by urea Kt/V [1,3]. The improvement in urea clearance was correlated to a postulated favourable effect on dialyser fibre permeability mediated by the intra-dialyser anticoagulants properties of citrate [1,3,8]. Considering the importance of limiting the biocompatibility related coagulation activation taking place in the extracorporeal circuit [9-17], disposing of a simple way to inhibit it without affecting the systemic coagulation and the bleeding risk [18] is very promising.

Even if thousands of patients have been treated in the recent years with haemodialysis fluids based on citric instead of acetic acid, the haemodynamic tolerance (the reduction in ionized calcium concentration and the increase in bicarbonateamia could both result in a lower intra-dialytic blood pressure [19-25]) and the amount of systemic coagulation activation related to each one of the modalities, were not investigated.

The aim of this randomized, controlled, single blind, cross-over study in single-use dialyser bicarbonate haemodialysis, is to detail the consequences on systemic haemodynamics, coagulation activation, acid-base status, calcium balance and dialysis efficiency of using citric instead of acetic acid in the haemodialysis fluids.

Methods and patients: