[On-line hemodiafiltration without acetate].

PURPOSE: The suitably filtered dialysate which is currently reinfused during on-line hemodiafiltration (HDF-OL) contains bicarbonate and small doses of acetate. The trend of acetataemia During "forced" convective treatments has never been studied. The gain in acetate secondary to the considerable quantities of fluids infused might have clinical significance in relation to the well-known side effects of this anion. METHODS: In this pilot study 12 patients underwent HDF-OL with reinfusion in predilution of 40 L of substitution fluids containing or not 3 mmol/L of acetate. Apart from this variable, all the other treatment parameters were the same in both procedures. The treatments were carried out in two short consecutive intervals in a random sequence. RESULTS: During HDF-OL the use of dialysate containing small doses of acetate is associated with levels of acetataemia 5-6 times higher compared to the basal. HDF-OL without acetate cancels out this increase. The acetate gained by the patients is significant, on average 75 mmol, and accounts for over 1/3 of the global base gain. Consequently, the bicarbonataemia levels at the end of treatment are significantly higher in HDF-OL with acetate than in the treatment without. Two hours after the end of the treatments the IL-6 levels tend to grow in both methods, but numerically less in HDF-OL without acetate; the difference verges on meaningfulness. CONCLUSIONS: The acetate gain is significant during forced convective treatments carried out with standard dialysate. This acetate gain can trigger cytokinin activation. These events are cancelled out by eliminating the acetate from the dialysate. The absence of this anion will be compensated with appropriate increases in the concentration of bicarbonate in the dialysis fluid.