Extracorporeal Techniques Based on Adsorption: Nomenclature, Hardware, and Circuit Design

Sorbents have been utilized in the past for intoxication and poisoning, but their spectrum of clinical application is now expanding. Hemoadsorption (HA) is still indicated for toxin and poison removal, but other molecules are considered appropriate targets for this blood purification modality. HA combined with hemodialysis (HA + HD) has been proposed for end-stage kidney disease patients to remove molecules that are not easily removed by classic HD or hemodiafiltration. More recently, a rationale for the use of sorbents in critical illness, sepsis, and acute kidney injury has emerged due to the proposed humoral theory behind these disorders. Pathogenetic circulating molecules in critical illness (damage- and pathogen-associated molecular patterns) cannot be sufficiently removed by classic continuous renal replacement therapies. New sorbent-based extracorporeal therapies have therefore been designed to remove these molecules, offering potential biological and clinical benefits. There is also the possibility of employing selective sorbents to target specific molecules or to perform nonspecific HA for a wide spectrum of molecules. Moreover, there is the possibility of separating plasma from blood and then applying adsorption to plasma or of combining HA with other extracorporeal therapies. Here, we describe a complete appraisal of current available techniques utilizing adsorption.