Hemoadsorption and plasma adsorption: two current options for the 3rd dimension of dialysis purification

The adsorption technique has opened a new frontier in the field of purification through hemodialysis. This technique has proved to be effective in removing uremic toxins previously deemed inaccessible due to their size or charge, as well as to their molecular interactions with blood proteins. In this context, this review provides a detailed explanation of the role of Polyester-polymer alloy (PEPA®) membranes and hemodiafiltration with endogenous reinfusion. The polyester-polymer alloy membrane is a three-layered dialysis membrane with adsorbent properties, representing an innovative approach to engineering the filter membrane to achieve adsorbent characteristics while maintaining biocompatibility with blood. Haemodiafiltration with endogenous reinfusion is a technique where a first filter separates plasma water from blood, then plasma water is led to a sorbent cartridge. After contact with the sorbent, the purified plasma water reconstitutes the whole blood, which is led to a second filter where diffusion takes place. Both techniques are efficacious in removing middle-molecular weight molecules and protein-bound toxins, and have a role in reducing inflammation and erythropoietin resistance. However, the additional clinical advantage of adsorption is partially offset by lack of selectivity in the absorption process, potentially resulting in the loss of micro- and macronutrients or drugs. Therefore, further studies are encouraged to evaluate the impact of absorption on patient outcomes and clinical applicability in certain medical conditions.