**6. Summary**

**Figure 5.** (a): Dialysate flow rate dependence of the spKt/V value in dialyser FDY150GW (b): Dialysate flow rate de‐ pendence of the spKt/V value in dialyser FX60 (c): Dialysate flow rate dependence of the spKt/V value in dialyser Vi‐

At a constant blood flow rate (QB=300 ml/min), a group of 6 patients received three treatments each at QD=300, 500 und 800 ml/min, with each set repeated for each of the 3 types of dialysers tested in vitro. In order to assess the effectiveness of treatment, the urea reduction ratio, single pool Kt/V (spKt/V) and equilibrated Kt/V (eqKt/V) were obtained (Daugirdas formula). In addition, OCM data were obtained for the dialysis machine FMC 5008 (Eff.Kt, Eff.Kt/V).

The figures show (as do the urea reduction ratios and eqKt/V results) that each step increase

The interesting question for dialysis patients is of course the exact impact this may have on treatment time. A sample calculation using results from the FX60 dialyser will demonstrate

*Patient BWopt Vcalc K300 K500 K800 KtV300 t300 tcalc500 tcalc800 t300-t500 t300-t800 No. kg L ml/min ml/min ml/min min min min min min* 75.0 37.1 186 199 209 1.18 240 220 209 **20 31** 60.0 26.9 181 197 207 1.57 240 215 204 **25 36** 66.0 23.0 158 190 202 1.35 180 163 154 **17 26** 75.5 33.6 184 202 216 1.71 300 285 267 **15 33** 69.0 31.8 173 199 207 1.36 240 217 208 **23 32** 69.5 27.9 178 188 201 1.93 300 287 268 **13 32**

**Table 3.** Time saved by using a dialysate flow rate of QD=500 ml/min or QD=800 ml/min instead of a dialysate flow rate

in dialysate flow can significantly improve the effectiveness of haemodialysis.

(Vcalc from OCM EffKt and measured Kt/V; tcalc=Kt/V(QD300)\*V/K)

taPES150HF

196 Updates in Hemodialysis

this (see Table 3).

of QD=300 ml/min

In vitro measurements obtained from a number of different modern high flux dialysers show that the characteristics "Clearance (QB, QD)" manage to closely match theoretical scenarios of expected interdependence. However, in spite of a number of different structural improve‐ ments, the KoA value remains dependent upon the dialysate flow rate. A higher dialysate flow rate of around 800 ml/min ensures that the fibre bundle is bathed more evenly in dialysate, thus improving the effectiveness of dialysis.

In vivo investigations confirm that increases in dialysate flow rates are likely to produce significantly improved Kt/V values.
