[Acetate-free biofiltration: a possible method of renal replacement therapy]

Acetate-free biofiltration (AFB) is a haemodiafiltration method which is used nowadays in the treatment of chronic renal failure. In AFB a dialyzation solution without a buffer is used, in the haemofilter some 2 1/hour are filtred. Simultaneously a sodium bicarbonate infusion in a postdilution mode is administered. The AFB investigation was conceived with the aim to introduce the method into clinical practice and to record the effect of AFB on the patient.

Using the apparatus Monitral SC 30 of Hospal Co. the author made 120 AFB in 23 patients on long-term bicarbonate haemodialysis. In the investigation capillary haemofilters with an AN 69 membrane (Filtral 10 and 12) were used. The blood flow rate was 260 +/- 23 ml/min, the infusion rate of the substitution solution (NaHCO3 with a concentration of 167 mmol/l) was 1.7 +/- 0.1 l/h, the AFB period of 3.64 +/- 0.25 h. Before and after AFB values of the acid-base balance were investigated as well as the ion concentration, nitrogen catabolites, beta-2-microglobulin and cardiovascular stability of the patients. Optimal adjustment of metabolic acidosis was proved, the pH value before vs. after AFB was 7.359 +/- 0.053 vs. 7.444 +/- 0.048, p < 0.001, standard HCO3 20.2 +/- 2.6 vs. 26.0 +/- 2.1 l mmol/l, p < 0.001, adjustment of the ion balance, nitrogen catabolites were effectively eliminated, the Kt/V value was 1.03 +/- 0.22, beta-2-microglobulin declined after AFB from 36.3 +/- 10.0 to 23.8 +/- 8.2 mg/l, p < 0.001. Cardiovascular stability of patients in the course of AFB was very good, symptomatic hypotension was recorded in one patient (0.83%).

AFB is considered by the authors, based on the results of their study and according to data in the literature, an effective and perspective form of substitution of renal function. AFB is particularly suitable for patients with circulatory instability and for those with a limited perspective of renal transplantation who are thus threatened by complications of long-term dialyzation treatment.