New Dialysis Technology and Biocompatible Materials

Although haemodialysis is an established treatment for patients with end-stage kidney disease, sustaining life for more than 2 million patients world-wide, the mortality of dialysis patients remains high and is greater than that for some of the more common solid organ cancers. As such, the question arises as to whether more efficient clearance of the waste products of metabolism which accumulate would improve outcomes. Recent reports of an association between improved patient survivals with higher-volume on-line haemodiafiltration exchanges would support this hypothesis. This has led to both the development of newer dialyser designs based on microfluidics using convective clearances to increase middle-molecule clearances and also a generation of superflux dialysers designed to remove larger-molecular-weight azotaemic toxins which have yet to be studied in large randomised prospective clinical trials. However, haemodiafiltration and superflux dialysers do not affectively clear protein-bound azotaemic toxins, and there is accumulating evidence that some of these toxins increase cardiovascular morbidity and mortality. This has led to resurgence in the interest of developing adsorption devices, using activated carbon technology, and the development of composite dialyser membranes by either adding carbons or other biomaterials to increase adsorption capacity to the standard dialyser. While anaphylactoid reactions used to be a recognised complication of haemodialysis, improvements in dialyser membrane bioincompatibility and changing sterilisation techniques have markedly reduced these reactions. Organic chemicals can leach out from the plastics in the blood lines and dialyser, and attention is required to adequately rinse the extracorporeal circuit to reduce patient exposure.