[Bicarbonate balance in hemodiafiltration (HDF): a comparison between two infusion methods of on-line prepared...

Hemodiafiltration (HDF) has high removal rates of low and middle-high molecular weight uremic toxins. We aimed to understand the efficacy and the safety in correcting on-line HDF acidosis. We compared two infusion methods of on-line prepared solution in HDF: HDF with an infusion solution produced from dialysate (HDF-OL) and HDF with a solution from patient ultrafiltrate after regeneration (HFR).

Eleven patients (four males, seven females) age 66 +/- 10 yrs, dialysis age 5.0 +/- 1.3 yrs, on anuria had two dialysis methods for the 1st session of the week, one HDF-OL and one HFR in 2 different weeks. In HDF-OL a high-flux polysulphone dialyser 1.8 m2 was used, in HFR a two-stage filter was used: polyetersulfone 0.7 m2 + SMC 1.95 m2 and a sorbent cartridge Selecta plus (Bellco) to regenerate the ultrafiltrate. HCO3- in the dialysis bath was 32 mmol/L.

Plasma bicarbonates, before dialysis were 21.6 +/- 2.1 mmol/L on HDF-OL and 21.5 +/- 3.3 on HFR (p=ns), at the end they were 27.5 +/- 1.8 mmol/L on HDF-OL and 27.8 +/- 1.2 mmol/L on HFR (p=ns). On HDF-OL bicarbonates reached a plateau at mid session: 27 +/- 1.2, 27.5 +/- 1.2, 27.5 +/- 1.8 to 120, 180 and 240 min respectively. On HFR the plateau was reached more slowly: 26.1 +/- 1.9, 27.1 +/- 1.4, 27.8 +/- 1.2 with the same times.

HFR-OL and HFR efficaciously corrected acidosis in a 4-h dialysis session. The same results, statistically and clinically, were achieved with infusion solution derived from dialysate and from solution from regenerated ultrafiltrate. In the latter, it was interesting that the global quality of the infusion solution was obtained from a close circuit from the patient ultrafiltrate.