Bicarbonate Hemodialysis: Influence on Plasma Refilling and Hemodynamic Stability

Abstract

The present study compares the effect of sodium bicarbonate (LoNaHCO₃, Na = 134, HCO₃ = 33 mEq/l) and sodium acetate (LoNaAc, Na =134, acetate 33 mEq/l) dialysate on the extravascular fluid mobilization (V_FM) and hemodynamic changes in 6 patients during 3 h of hemodialysis with equivalent fluid ultrafiltration of about 600 ml/h. The cumulative decrease in plasma volume after 1, 2 and 3 h of dialysis was significantly less during LoNaHC0₃dialysis than during LoNaAc dialysis, with plasma volume almost completely refilled by V_FM during the first 2 h of LoNaHCO₃ dialysis. High sodium acetate dialysate (HiNaAc, Na = 144, acetate = 33 mEq/l) with equivalent fluid ultrafiltration also resulted in less net decrease in plasma volume and greater V_FM than LoNaAc, although the temporal pattern of refilling was somewhat different from that during LoNaHCO₃: rapid and complete refilling during the early portion of LoNaHCO₃, slower and more progressive refilling during HiNaAc, with similar cumulative refilling for LoNaHCO₃ and HiNaAc by 3 h. Mean arterial pressure (MAP) tended to decrease during LoNaAc dialysis, whereas MAP remained stable during LoNaHCO₃ and increased slightly during HiNaAc. This study, therefore, suggests that improved hemodynamic stability utilizing bicarbonate dialysate may be due, in part, to greater plasma refilling and better preservation of plasma volume.