International Renal Research Institute of Vicenza, Vicenza, Italy.
Department of Nuclear medicine, San Bortolo Hospital, aULSS8 Berica, Vicenza, Italy.
Blood Purif. 2018;46(3):196-204. doi: 10.1159/000489993. Epub 2018 Jun 8.
Inadequate removal of molecules between 5 and 50 KDa may cause long-term complication in chronic hemodialysis. Medium cut-off (MCO) is a new class of membranes with enhanced sieving properties and negligible albumin loss. MCO membrane makes it possible to perform expanded hemodialysis (HDx), a technique based on high internal filtration (IF).The present study is designed to quantify IF in 2 MCO dialyzers (Theranova 400 and 500, Baxter, Deerfield, USA) using a nuclear imaging technique previously validated.
Blood and dialysate compartment pressure drop along with transmembrane pressure; they were measured in a closed in vitro circuit with human blood (blood flow [QB] = 300 and 400 mL/min; dialysate flow 500 mL/min; net ultrafiltration rate 0 mL/min). A non-diffusible marker molecule (albumin macro-aggregates labeled with 99Tc metastable) was injected in the blood compartment and nuclear emission was recorded by a gamma camera. Relative variations in the concentration of the marker molecule along the length of the filter were used to calculate local cross filtration.
Based on marker concentration profiles, IF was estimated. For Theranova 400, IF were 29.7 and 41.6 mL/min for QB of 300 and 400 mL/min. For Theranova 500, IF were 31.6 and 53.1 mL/min for QB of 300 and 400 mL/min respectively.
MCO membrane provides significant amounts of IF due to the particular combination between hydraulic permeability of the membrane and reduced inner diameter of the fibers. High IF combined with enhanced sieving profile of MCO membrane leads to improved removal of a wider spectrum of uremia retention molecules in HDx, without requiring complex equipment.
在慢性血液透析中，如果不能有效清除 5 到 50 kDa 之间的分子，可能会导致长期并发症。中截留（MCO）是一类新型膜，具有增强的筛分性能和可忽略不计的白蛋白损失。MCO 膜使进行扩展血液透析（HDx）成为可能，这是一种基于高内过滤（IF）的技术。本研究旨在使用先前验证过的核成像技术来量化 2 种 MCO 透析器（百特的 Theranova 400 和 500）中的 IF。
在一个封闭的体外回路中，用人体血液（血流 [QB] = 300 和 400 mL/min；透析液流量 500 mL/min；净超滤率 0 mL/min）测量血液和透析液隔室压力降以及跨膜压力。将一种不可扩散的标记分子（用 99Tc 亚稳态标记的白蛋白大聚集体）注入血液隔室，并用伽马相机记录核发射。沿过滤器长度变化的标记分子浓度的相对变化用于计算局部交叉过滤。
根据标记浓度分布，估计了 IF。对于 Theranova 400，QB 为 300 和 400 mL/min 时，IF 分别为 29.7 和 41.6 mL/min。对于 Theranova 500，QB 为 300 和 400 mL/min 时，IF 分别为 31.6 和 53.1 mL/min。
MCO 膜由于膜的水力渗透性和纤维内径降低之间的特殊组合，提供了大量的 IF。高 IF 与 MCO 膜增强的筛分特性相结合，可在 HDx 中更有效地清除更广泛的尿毒症保留分子，而无需复杂的设备。
