CLINICAL-EVALUATION OF 4 DIFFERENT HIGH-FLUX HEMODIALYZERS UNDER CONVENTIONAL CONDITIONS IN-VIVO

Four types of high-flux hemodialyzers, Primus 2000 (high-flux polysulf one 2.0 mc(2), Altra-Flux 170 G (cellulose diacetate 1.7 m(2)), FLX-15 GW (polyester-polymer alloy 1.5 m(2)) and PAN-85 DX (polyacrylonitril e 1.7 m(2)) were evaluated in vivo. A total of 12 stable chronic hemod ialysis patients participated in the study and each type of dialyzer w as tested once in 9 of them. Blood samples for the measurement of BUN, creatinine, phosphate, uric acid, albumin and beta(2)-microglobulin ( beta(2)M) were drawn before and 5 min after the end of the study dialy sis. During dialysis, which was performed in all patients with a blood flow rate of 250 ml/min for 240 min, the dialysate (550-600 ml/min) w as collected every hour and samples were drawn for the measurements of all the above substances. The mean total amount of low-molecular subs tances removed per session by each dialyzer was very close to 19.5 g f or urea, 2.0 g for creatinine, 0.9 g for phosphate and 1 g for uric ac id. The one-third (30-33%) of the above amounts were removed during th e first hour of dialysis. Dialyzers' clearances for creatinine and uri c acid were significantly higher in Primus dialyzer comparing to FLX-1 5 GW (p < 0.05) while the clearance for urea showed a borderline signi ficance (p = 0.055). No difference was found either among Altra-Flux 1 70 G? FLX-15 GW and PAN-85 DX or between Primus and PAN-85 DX dialyzer s. Phosphate clearance did not show any difference among the four dial yzers. The lowest amount of albumin removed per session was 0.75 g by PAN-85 DX and the highest 1.8 g by FLX-15 GW, while the equivalents fo r beta(2)M were 80 mg by Altra-Flux 170 G and 142 mg by PAN-85 DX. A s ignificant adsorption of beta(2)M on these dialysis membranes was indi cated by the combination of a satisfactory serum beta(2)M reduction ra tio (post-/predialysis values = 0.52, 0.77, 0.60, 0.55) with a reduced beta(2)M clearance (23.9, 13.6, 20.2. 25.1 ml/min). During the first hour of dialysis, in comparison to the following time, the highest amo unts of albumin and beta(2)M (expressed as percentage of total) were r emoved by the Primus 2000 dialyzer. Our results indicate that under co nventional conditions small differences in the surface area of the hig h-flux dialyzers are unimportant regarding the removal of low molecule s. However, the composition of the membrane seems to play an important role in the removal of high-molecular substances.