E-Mail karger@karger.com Editorial Blood Purif 2017;44:I–VIII DOI: 10.1159/000476012 The Rise of Expanded Hemodialysis Claudio Ronco a, b a Department of Nephrology Dialysis and Transplantation, St. Bortolo Hospital, and b International Renal Research Institute, Vicenza, Italy apy called “expanded hemodialysis.” Its simple set up and application offer the possibility to use it even in patients with suboptimal vascular access or even with an indwelling cath- eter. The system does not require particular hardware or un- usual nursing skill. The quality of dialysis fluid is, however, mandatory to ensure a safe conduction of the dialysis ses- sion. This new therapy is likely to modify the outcome of end- stage kidney disease patients, thanks to the enhanced re- moval of molecules traditionally retained by current dialysis techniques. © 2017 S. Karger AG, Basel Introduction Significant improvements have been made to hemodi- alysis over the years leading to longer survival and im- proved quality of life in patients with end-stage kidney disease (ESKD). However, despite technological advances and improved patient care, long-term outcomes are still suboptimal with a high rate of hospitalization and mortal- ity. This is partly due to a case mix, with older and sicker patients presenting a high prevalence of comorbidities. Nevertheless, important limitations of current dialysis techniques emerge clearly with several uremic solutes in- adequately removed even by the most sophisticated renal replacement therapies [1–6]. While we are struggling with these challenges, health care systems are fixing boundar- ies to the overall expenditure and budgets, being con- Abstract The low water permeability feature of original cellulosic membranes was considered an advantage in the absence of dialysis equipment that are capable of controlling water re- moval. The advent of ultrafiltration control systems led to the development and use of high-flux (HF) membranes that allowed improved middle molecule removal including β-2 microglobulin. Further advances in technology allowed bet- ter control over the structure and permeability of mem- branes. Different polymers and improved spinning modali- ties led to significant advances in solute removal and hemo- compatibility. Inner surface modification produced a reduction in membrane thrombogenicity and protein-mem- brane interaction with a less tendency to fouling and perme- ability decay. Further evolution in technology led to the de- velopment of a new class of membranes referred to as pro- tein-leaking membranes or super-flux or high cutoff (HCO). These membranes are more permeable than conventional HF membranes and allow some passage of proteins, includ- ing albumin. The rationale for these membranes is the need for increased clearance of low molecular weight proteins and protein-bound solutes. However, albumin loss in pro- tein-leaking HCO membranes represents a limitation whose effect in patients is still controversial. The last evolution in the field of membranes is the development of a new class defined as “high retention onset” (HRO) due to the peculiar high sieving value in the middle to high molecular weight range. The introduction of HRO membranes in the clinical routine has enabled the development of a new concept ther- Published online: May 10, 2017 Claudio Ronco, MD Department of Nephrology, Dialysis and Transplantation International Renal Research Institute of Vicenza (IRRIV) San Bortolo Hospital, Viale Rodolfi 37, IT–36100 Vicenza (Italy) E-Mail cronco  @  goldnet.it © 2017 S. Karger AG, Basel www.karger.com/bpu