**Author details**

According to the Italian study [17], on-line HDF/HF is a useful tool for treating patients with dialysis induced hypotension. Then diafilters with higher hydraulic permeability with little albumin loss that do not aim to achieve higher solute removal may be useful for those patients. Not to mention, design specifications of dialyzer/diafilter is as important as the membrane

Many classic problems with biocompatibility in the past such as transient leukopenia, complement activation, negative charge syndrome, etc., have already been dissolved by modifying physical and chemical structures of the dialysis membrane. Most currently available synthetic polymeric membranes, however, employ PVP as a hydrophilic agent as well as a pore-forming agent. Study shows that many symptoms including abrupt decrease of blood pressure or shock right after starting treatments could be induced most probably due to PVP included in the membrane, and it is sometimes called "PVP intolerance". Novel hydrophilic agents may be studied for the purpose of replacing PVP. Alternately, novel casting technique in which no hydrophilic agent is necessary has to be studied, knowing that PMMA, EVAL, and PEPA are cast with no additives although they are also originated from petroleum.

Surface modification with the third substances is another way to obtain membranes with preferred permeability as well as biocompatibility. For example, PSf membrane coated with vitamin E showed a great success for reducing reactive oxygen species (ROS) as well as free radicals that also showed preferable clinical results (Terumo, Asahi-Kasei). Toray introduced a novel technique with NV polymer to their PSf membrane to reduce adsorp‐ tion of cells as well as protein molecules on the membrane. Although both two mem‐ branes work well clinically, they still utilize PVP in the same amount as previously included before. Then it should be noted since surface modification is closely related to solute transport as well as biocompatibility, biomimicry situations under dialysis must be further

Since hemodialysis experiments with canines were first reported, many membranes, either natural or synthetic polymeric ones, have been developed and the latter have been the main stream due to higher solute and hydraulic permeabilities as well as better biocompatibility. The mass transport mechanism across the membrane can be expressed by the Fick's 1-st law of diffusion; however, not only the membrane permeability but also the design specifications

The chemical structure of the dialysis membrane determines the hydrophilicity and hydro‐ phobicity of the membrane. Since all synthetic polymeric membranes are made from petrole‐ um, they are hydrophobic in nature. Most of these membranes include a hydrophilic agent

are important for assembling dialyzers with better performances.

permeability in terms of solute removal under given therapeutic conditions.

**7.2. Biocompatibility**

184 Updates in Hemodialysis

**7.3. Surface modification and adsorption**

taken into consideration.

**8. Conclusions**

Akihiro C. Yamashita1\* and Kenji Sakurai2\*

\*Address all correspondence to: yama@hosei.ac.jp

1 Department of Chemical Science and Technology, Faculty of Bioscience and Applied Chemistry, Hosei University, Kajino-cho, Koganei, Tokyo, Japan

2 Hashimoto Clinic, Hashimoto, Midori-ku, Sagamihara, Kanagawa, Japan
