On-line haemodiafiltration with and without acetate

Background. In patients on on-line convective treatments, given the considerable quantity of dialysis fluid re-infused, the small amount of acetate present in bicarbonate dialysis fluid as a pH stabilizing factor may allow a significant transfer of that anion to the patient, possibly inducing cytokine activation. Methods. To verify this hypothesis, we performed on-line haemodiafiltration (OL-HDF) with (3 mmol/l) and without acetate in dialysis fluid in a cross-over randomized order on 12 prevalent patients. Results. In comparison with the pre-treatment values, plasma acetate levels were unchanged during and after acetate-free OL-HDF, while they were 5–6 times higher in the course of OL-HDF containing acetate in dialysis fluid; plasma acetate levels returned to basal values 2 h after the end of the procedure. The total increase of bases in the patient attributable to acetate was 36%. Plasma bicarbonate values at the end of treatment were significantly lower in treatments without acetate, as compared to those with acetate. Interleukin-6 plasma levels were super-imposable at the beginning and in the course of the two methods compared, but there was a tendency towards a greater increase at an interval of 2 h following OL-HDF with acetate. Conclusions. Our preliminary results confirm the assumption that body gain of acetate is particularly high in convective treatments, while acetate-free OL-HDF slows down acetate burden. Clinical advantages due to these effects should be evaluated in properly designed prospective studies.