Disruptive technologies for hemodialysis: medium and high cutoff membranes. Is the future now?

Abstract

In the past decade, a new class of hemodialysis (HD) membranes (high retention onset class) became available for clinical use. The high cutoff (HCO) and the medium cutoff (MCO) membranes have wider pores and more uniformity in pore size, allowing an increased clearance of uremic toxins. Owing to the mechanism of backfiltration/internal filtration, middle molecules are dragged by the convective forces, and no substitution solution is needed. The HCO dialyzer is applied in septic patients with acute kidney injury requiring continuous kidney replacement therapy. The immune response is modulated thanks to the removal of inflammatory mediators. Another current application for the HCO dialyzer is in hematology, for patients on HD secondary to myeloma-kidney, since free light chains are more efficiently removed with the HCO membrane, reducing their deleterious effect on the renal tubules. In its turn, the MCO dialyzer is used for maintenance HD patients. A myriad of clinical trials published in the last three years consistently demonstrates the ability of this membrane to remove uremic toxins more efficiently than the high-flux membrane, an evolutionary disruption in the HD standard of care. Safety concerns regarding albumin loss as well as blood contamination from pyrogens in the dialysate have been overcome. In this update article, we explore the rise of new dialysis membranes in the light of the scientific evidence that supports their use in clinical practice.

Acute Kidney Injury and Blood Purification Techniques in Severe COVID-19 Patients

“…Middle molecular weight molecules, including cytokines in the range of 20 kDa to 50 kDa, are successfully removed both with MCO and HCO hemofilters by means of diffusion and convection. The difference between MCO and HCO membranes resides in a narrower range of pore size (mean pore radius is 5 nm and 10 nm, respectively), providing a more selective remotion of solutes with negligible serum albumin losses when using MCO routinely compared to HCO filters [ 122 ]. Previous trials have documented a reduction in both plasma levels of inflammatory cytokines and transcription of pro-inflammatory cytokines due to the enhanced removal of soluble mediators with MCO membranes [ 123 ].…”

“…TPE is associated with the risk of hypocalcemia due to the use of citrate as an anticoagulant, which chelates calcium; the risk of transfusion reactions due to replacement fluid (most commonly, hypotension when albumin is used, and urticaria when plasma is used); and significant removal of coagulation factors, medication, endogenous immunoglobulins, anti-inflammatory mediators, and therapeutic monoclonal antibodies [ 133 ]. As stated above, HCO membranes are associated with significant serum albumin losses, that are mitigated with the use of MCO membranes [ 122 ].…”

Injúria renal aguda e métodos de suporte: padronização da nomenclatura

“…Suporte reNal artificial extracorpóreo 3,[17][18][19][20][21][22] HeModiálise convencional -Duração: até 6 horas.…”

Tree‐like PA6/PVP/CS hemodialysis membrane to improve the contradiction between medium molecular toxins and proteins

“…To improve the removal of medium molecular molecules, Dehghan et al 13 explored the effect of different molecular weight polyvinylpyrrolidone (PVP) to achieve a high cut‐off (HCO) membrane in cooperation. HCO membranes can significantly improve the removal of middle molecular toxins, but there is a problem of high albumin loss 14,15 . Based on this, many researchers have proposed a medium cut‐off (MCO) membrane with a molecular weight cut‐off value close to that of albumin to achieve high medium molecule toxin removal ability while preventing protein loss 16–19 .…”

“…HCO membranes can significantly improve the removal of middle molecular toxins, but there is a problem of high albumin loss. 14,15 Based on this, many researchers have proposed a medium cut-off (MCO) membrane with a molecular weight cut-off value close to that of albumin to achieve high medium molecule toxin removal ability while preventing protein loss. [16][17][18][19] However, the process of customized pore size is complex and demanding, so the MCO membrane is not easy to prepare.…”