Flux of Dialysis Membrane: Benefit and Risk

Fig. 6.1

Backfiltration, back diffusion of pyrogen, activation of complement, monocyte, neutrophils

Traditional cellulose-type membranes are known to have a lower adsorption capacity for pyrogens . On the other hand, synthetic polymer membranes also have a higher adsorption capacity for pyrogens , which may contribute to prevent back diffusion and backfiltration of pyrogens . However, even in the synthetic polymer membranes with a higher adsorption capacity, it is difficult to block back diffusion and backfiltration of pyrogens because the mean membrane pore size is large.

In 2008, the Japanese Society for Diabetes Therapy published “Standard on Microbiological Management of Fluids for Hemodialysis and Related Therapies,” which is the most strict standard in the world (Kawanishi et al. 2009) (Table 6.1).

Table 6.1

JSDT Standard on microbiological management of fluids for hemodialysis 2008

• Dialysis water (reverse osmosis (RO) water)
Bacteria: <100 CFU/mL	Endotoxin: <0.050 EU/mL
• Standard dialysis fluid
Bacteria: <100 CFU/mL	Endotoxin: <0.050 EU/mL
• Ultrapure dialysis fluid
Bacteria: <0.1 CFU/mL Endotoxin: <0.001 EU/mL (less than the detection limit)
Note: The action level shall be set depending on the quality condition of each facility, typically at 50% of the maximum allowable level, except for the endotoxin level of ultra-pure dialysis fluid
• Online prepared substitution fluid
Sterile and non-pyrogenic Bacteria: <10⁻⁶ CFU/mL	Endotoxin: <0.001 EU/mL (less than the detection limit)

6.6.2 Loss of Necessary Elements such as Albumin in the Body

In dialysis therapy for patients with end-stage kidney disease (ESKD), there has been an effort to remove middle molecules and protein-bound molecules as well as small water-soluble molecules (Vanholder et al. 2008). To remove protein-bound molecules , the membrane with larger pore size is needed, but it also removes necessary elements such as albumin . Therefore, there is a risk of loss of necessary elements in the body (Fournier et al. 2015).

6.7 Does High-Flux Membrane Contribute to Improving Survival?

The flux (solute and water permeability) of membrane has been increased to remove uremic toxins with larger molecule toxins. Here, we look at the effect of high-flux membrane on survival of dialysis patients.

The membrane permeability outcome (MPO) study, a 3-year observational study, investigated the effect of membrane type on patient survival by comparing the survival rates between dialysis patients using high-flux membrane (mean UFR, 44.7 mL/min) and those using low-flux membrane (mean UFR, 9.8 mL/min). The study also compared the survival rates between the two groups according to the presence/absence of diabetes mellitus and hypoalbuminemia (≤4 g/dL or >4 g/dL). Overall, there was no significant difference in survival rates between the two groups. However, subanalysis showed that patients with diabetes and patients with hypoalbuminemia had significantly higher survival rates in the high-flux group compared with the low-flux group. In addition, the blood concentration of β2-microglobulin was significantly lower in the high-flux group compared with the low-flux group (Locatelli et al. 2009).

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