Membrane designs and composition for hemodialysis, hemofiltration and hemodialfiltration: past, present and future.

Today hemodialysis is a routine outpatient treatment, not only carried out in hospitals, but more commonly in free standing units without on site medical supervision. One of the key advances that have underpinned this expansion of hemodialysis provision has been the technological advances in dialyzer membrane technology. Dialyzer membranes have undergone a sea change from collodion tubes to cellulose sheets to the modern day capillary fiber dialyzer. Improvements have not only been limited to reliability of manufacture, but also reduction in bio-incompatibility, and improved small solute clearances. However, the holy Grail remains the development of a dialyzer capable of removing middle sized azotemic retention solutes, and protein bound or lipophilic solutes.