Citrate anticoagulation and dialysate with reduced buffer content in chronic hemodialysis

Anticoagulation with trisodium citrate (510 mmol/l) at a rate of 126 ml/h in combination with a calcium-free, 35 mmol/l acetate dialysate and i. v. supplementation of calcium chloride (350 mmol/l) at a rate of 22.5 ml/h has been performed in renal failure patients at risk of bleeding or actively bleeding. Short-term use-i. e. on the average four dialyses in 15 patients-showed no adverse effects or clotting phenomena. However, long-term use-i. e. at least four weeks and on average sixteen dialyses in six chronic hemodialysis patients-caused paresthesias and muscular cramps possibly due to the combination of insufficient calcium supplementation and metabolic alkalosis. To prevent metabolic alkalosis, the acetate content of the dialysate and the infusion rate of citrate were reduced to 29.5 mmol/l and 100 ml/h, respectively. To prevent clotting at this infusion rate, a calcium and magnesium-free dialysate was used and i. v. supplementation of calcium chloride (350 mmol/l) and magnesium chloride (250 mmol/l) was performed at rates of 30 ml/h and 15 ml/h, respectively. Six chronic renal failure patients were dialyzed with this regimen for an average of four months. There were no side effects or metabolic alkalosis noted. When an equimolar amount of bicarbonate replaced the acetate in the calcium and magnesium-free dialysate, side effects and metabolic alkalosis were seen within three dialyses. When the bicarbonate concentration in the dialysate was reduced to 25 mmol/l neither side effects nor metabolic alkalosis was observed. Thus citrate anticoagulation in patients on chronic hemodialysis can only be performed when the buffer content of the dialysate is reduced.