**4. Performance evaluation in vivo**

The biocompatibility and separation performance of PES-based hemodialysis membranes in vivo are also discussed. Animal experiments are carried out to evaluate the PES hollow fiber membranes firstly, and goat was selected as the experimental animal. Experiments were performed to evaluate the solute clearance and the blood compatibility. The blood compatibility and performance of the PES-based high-flux hemodialysis membrane in hemodialyzation were also clinically evaluated, and compared with those of two conventional high-flux membranes, polysulfone (PSF) and polyamide (PA) membranes. The PES and PSF membranes showed similar blood compatibility and solute clearance, and the blood compatibility for PES and PSF might be better than that of the PA membrane.

Polyethersulfone Hollow Fiber Membranes for Hemodialysis 79

Table 1 also summarizes the clearance data and the reduction ratio after the dialysis for small molecules in vivo. Changes in 2-microglobulin during the dialysis for the goats are

The ultrafiltration coefficient was obtained by the hemodialysis process using the simulated solution with a value of 81ml/h.mmHg, from which we could conclude that the PES

The PES membrane was able to reduce the plasma burden of 2-microglobulin during the treatment, as shown in Figure 8. The data were analyzed by consideration of actual values and the percentage reductions achieved. The reduction ratio was about 50% after the treatment for 4 hrs; this value is comparable to that for PSF membrane and polyflux

As shown in table 1, the reduction ratio for the 2-microglobulin was smaller than that for the urea and creatinine due to the higher molecular weight (p<0.05). The alteration of 2 microglobulin in plasma levels may not simply be a result of trans-membrane transport; the adsorption to the membrane may also play a role in the observed plasma changes (Hoenich & Katopodis, 2002). For the removal of 2-microglobulin, cellulose derived membrane is impermeable to 2- microglobulin due to its dense symmetrical structure which does not permit the easy diffusion or convection of proteins through the membrane, while polyacrylonitrile (PAN), polysulfone and polymethylmethacrylate (PMMA) membrane could be used (Moachona et al., 2002). The PMMA membrane could also adsorb 2 microglobulin. To remove 2-microglobulin more efficiently from plasma, hemodialysis membranes must therefore not simply be considered as filters of low-molecular-weight metabolites but should be equally assessed for their capacity to eliminate potentially deleterious low-molecular-weight plasma proteins. For the PES membrane, 2 microglobulin adsorption is not an important mechanism of removal. The large solute removal by the membrane is mainly caused by the asymmetric structure and the higher ultra-filtration coefficient, which was presumably caused by the larger pore size and the

plotted in Figure 8. The reduction ratio was about 50% after the treatment for 4hrs.

**4.1.2 Results and discussion** 

(Hoenich & Katopodis, 2002).

hydrophilicity of the membrane.

0

Fig. 8. Changes in 2-microglobulin during the dialysis. Data are expressed as the

0 50 100 150 200 250 Time (mins)

20

40

60

Normalized value (%

meansSD, n =3 (From reference, Su et al., 2008)

80

100

membrane was a high-flux hemodialysis membrane.

**4.1.2.1 Solute transport** 
