CITRATE-CONTAINING DIALYSATE FOR HIGH CLOTTING RISK HAEMODIALYSIS PATIENTS – A PILOT, RANDOMISED CROSSOVER TRIAL

CITRATE-CONTAINING DIALYSATE FOR HIGH CLOTTING RISK HAEMODIALYSIS PATIENTS – A PILOT, RANDOMISED CROSSOVER TRIAL

Titrating the optimal anticoagulation dose for haemodialysis patients is an important yet difficult task. Excessive anticoagulation leads to bleeding and systemic heparinization whilst insufficient anticoagulation leads to clotting. Citrate, often used in regional citrate anticoagulation in continuous renal replacement, chelates calcium which is a key player in the clotting cascade. Citrate-containing dialysate is marketed to improve solute clearance and potentially reduces clotting. It is unknown whether switching from acetate-containing dialysate to citrate-containing dialysate for patients with high clotting risks could negate the increment in anticoagulation. This study aims to reduce the usage of anticoagulation in haemodialysis patients.

A pilot randomised crossover trial was performed among haemodialysis patients (n=30) with high clotting risks. High clotting risk is defined as having a baseline 2000 International Unit (IU) tinzaparin and necessitate the increment of anticoagulation due to recent extracorporeal circuit clotting or significant thrombus formation in the venous chamber. It involved switching to citrate-containing dialysate in the intervention-phase and maintaining acetate-containing dialysate with an extra 500-IU tinzaparin in the comparator-phase. The primary endpoint was failure to complete the dialysis session due to clotting. Secondary endpoints included delivered dialysis dose Kt/Vurea, visual performance scale of venous chamber and dialyzer status (Fig. 1 & 2) and systemic calcium concentration.

144 sessions of haemodialysis were performed (Fig. 3). The primary outcome, clotting of the circuit causing premature termination of haemodialysis, occurred in 7 patients of the citrate-phase whilst it occurred in 2 patients of the acetate-phase, therefore was not statistically significant (Table 1). The secondary endpoint, delivered dialysis dose and visual dialyzer performance scale, favoured the acetate-containing dialysate with anticoagulation increment group, suggesting that there was more subclinical clotting in the citrate-containing group (Table 2). Systemic calcium level was similar except in the subgroup of 1.75mmol/L, in which the post-dialysate sample of the citrate-containing group was lower.

For patients with high clotting risks, switching from acetate- to citrate-containing dialysate allowed completion of the whole haemodialysis session without utilising an extra dose of low molecular weight heparin at mid-dialysis, although sub-clinical clotting was more severe. This is clinically significant as patients with both high bleeding and clotting risk can potentially keep a lower level of anticoagulation for their haemodialysis.