Can dialyzer membrane selection affect outcomes in patients with acute kidney injury requiring dialysis?

The choice of dialyzer membrane may potentially affect not only solute clearances but also blood-dialyzer interactions. Although on one hand alteration of the dialyzer surface or pore size to increase inflammatory mediator loss may potentially be beneficial for patients with acute kidney injury (AKI), dialyzer membrane interactions, which precipitate intradialytic hypotension, may worsen AKI. Several years ago cellulosic membrane dialyzers were shown to reduce both patient survival and renal recovery in patients with AKI. This review looks at the earlier studies of dialyzer membrane choice and outcomes in AKI, besides discussing the newer developments in membrane technology for patients with AKI.     

膜生物反应器中临界通量理论的研究

膜污染是影响膜生物反应器大规模化应用的重要因素之一,而膜生物反应器在低于临界通量运行时能有效减缓膜污染.介绍了临界通量理论的概念、测定方法、产生机理和影响因素,并对各影响因素间的相互关系做了探讨.其中临界通量概念有强弱两种形式,膜生物反应器工艺应用的主要为弱形式的临界通量;临界通量的测定方法主要包括流量阶梯法、压力阶梯法和滞后效应法等;临界通量存在的机理可归结于活性污泥粒子所受的趋向于膜表面的拖曳力与粒子的返混作用达到了平衡,而拖曳力与返混力的大小主要与膜与膜组件特性、混合液性质及操作条件有关,且各个因素间相互影响.     

Comparison of urea clearance in low‐efficiency low‐flux vs. high‐efficiency high‐flux dialyzer membrane with reduced blood and dialysate flow: An in vitro analysis

Rapid removal of small molecules during hemodialysis places an acutely ill patient with kidney failure at an increased risk of hemodynamic instability and for dialysis disequilibrium syndrome. The use of high‐flux, high‐efficiency (HEF) dialyzers may increase this risk despite reductions in blood and dialysate flow. We performed in vitro experiments to compare urea clearance at low dialysate flow and various blood flows using a low‐efficiency low‐flux (LEF) and a HEF membrane. Compared to LEF, there was a significant increase in the clearance of urea at all blood flows with the HEF (all P values < 0.005). HEF dialyzer (F180NR) had higher urea clearance at a blood flow of 150 mL/min than LEF dialyzer (F5) at blood flow of 300 mL/min (144.1 ± 0.99 vs. 130.1 ± 0.001 mL/min for F180 vs. F5, respectively, P < 0.002). Our data suggest that use of HEF dialyzer are not as safe as LEF in high‐risk acute dialysis patients since these are associated with more rapid removal of urea despite reduction in blood and dialysate flow as compared to LEF.     

Yellowish discoloration of dialyzer

A 43‐year‐old Chinese man with chronic viral hepatitis and end‐stage renal disease, receiving conventional hemodialysis for 6 years, presented with general malaise and abdominal fullness. After 4.5 hours of hemodialysis, the hollow fibers of the dialyzer turned yellow. Biochemistry studies showed hyperbilirubinemia. The actual serum bilirubin (7.4 mg/dL) could be proved. Abdominal echography survey was negative. Hyperbilirubinemia was secondary to acute exacerbation of chronic viral hepatitis. Anuria and skin hyperpigmentation in uremia lack the tea‐color urine and mask clinical jaundice in the presence of hyperbilirubinemia. Careful observation of dialyzer yellowish discoloration gave us timely discovery of patient's hyperbilirubinemia.     

微孔膜的可压缩性及参数变化对膜蒸馏跨膜传质速率的影响

针对两种聚四氟乙烯膜在膜两侧压差为10～100kPa范围内进行了气体渗透实验,结果表明：实验用膜具有一定的可压缩性,随膜两侧压差的增大,膜孔径r减小,而膜孔隙率与有效厚度的比值ε／τδ是增大的,且其变化幅度随膜厚度的增大而增大,通过求解数学模型方程得到了不同膜参数时直接接触式膜蒸馏和真空膜蒸馏跨膜传质速率的预测值,与相同条件下的膜蒸馏实验测定的传质速率进行对比,结果表明：由膜的可压缩性带来的膜参数变化能够使跨膜传质速率有所增长,采用相近压差下气体渗透实验测定的膜参数能够较准确地预测膜蒸馏的跨膜传质速率。     

旋转切向流管式膜微滤渗透通量模型研究

推导出了旋转切向流管式膜微滤的过滤渗透速度和膜通量的理论表达式 .实验和计算结果表明了模型的有效性     

影响一体式平板膜生物反应器临界通量的因素

利用阶梯式通量递增法测定了一体式平板膜-生物反应器中的临界通量,对不同操作条件下测定值的差异进行了考察.通过正交试验设计,研究了曝气强度、污泥浓度(MLSS)和滤液COD(SCOD)三个因素分别在0.8,1.2,1.5 m3/h;10,20,30 g/L和50,100和150 mg/L水平下对临界通量测得值的影响.研究发现,污泥浓度和SCOD均对临界通量测得值呈负影响作用,而曝气强度则起正作用.随着污泥浓度和SCOD的增大,临界通量测得值是逐步减小的;而曝气强度的增大在一定程度上可以提高临界通量值.其中,临界通量测定值受SCOD的影响最大,MLSS次之,曝气强度最小.     

膜蒸馏研究的新进展

对９０年代以来膜蒸馏工艺过程的影响因素、过程机理以及膜蒸馏用膜材料及膜结构几方面的研究和进展进行了综述。在此基础上提出了模蒸馏的研究方向。     

Effect of dialysis dose and membrane flux on hemoglobin cycling in hemodialysis patients

Many studies found that hemoglobin (Hb) fluctuation was closely related to the prognosis of the maintenance hemodialysis patients. We investigated the association of factors relating dialysis dose and dialyzer membrane with Hb levels. We undertook a randomized clinical trial in 140 patients undergoing thrice‐weekly dialysis and assigned patients randomly to a standard or high dose of dialysis; Hb level was measured every month for 12 months. In the standard‐dose group, the mean (±SD) urea reduction ratio was 65.1% ± 7.3%, the single‐pool Kt/V was 1.26 ± 0.11, and the equilibrated Kt/V was 1.05 ± 0.09; in the high‐dose group, the values were 73.5% ± 8.7%, 1.68 ± 0.15, and 1.47 ± 0.11, respectively. The standard deviation (SD) and residual SD (liner regression of Hb) values of Hb were significantly higher in the standard‐dose group and low‐flux group. The percentage achievement of target Hb in the high‐dose dialysis group and high‐flux dialyzer group was significantly higher than the standard‐dose group and low‐flux group, respectively. Patients undergoing hemodialysis thrice weekly appear to have benefit from a higher dialysis dose than that recommended by current KDQQI (Kidney Disease Qutcome Quality Initiative) guidelines or from the use of a high‐flux membrane, which is in favor of maintaining stable Hb levels.     

预处理剂对陶瓷膜表面性质及渗透通量的影响

考察了不同预处理剂对陶瓷膜表面性质及渗透通量的影响,结果表明:表面活性剂的加入,使陶瓷膜表面的负电性以及亲水性得到提高,膜渗透通量从100L/(m2·h)提高到200L/(m2·h);碱式氯化铝中Al3+在膜表面的吸附,导致膜表面呈现正电位,相应的膜渗透通量只有50L/(m2·h);吸附剂对渗透通量的影响主要体现其在乳化废水中表面电位的不同,呈负电性的二氧化硅有利于渗透通量的提高,而呈正电性的氧化铝会导致膜通量的下降.     

血液透析器膜材料研究进展

从膜材料的血液相容性、可纺性以及价格等因素出发,简要介绍了影响透析膜膜材料性能的因素.通过大量调研发现目前临床上的透析膜所使用的膜材料主要有纤维素类、聚砜类、聚丙烯腈类以及聚氨酯类等.在前人研究的基础上,对透析器膜材料的国内外进展情况作了全面综述,并对其发展趋势作出预测.     

Thrombocytopenia associated with dialysis treatments

We present a case of a 51-year-old woman who developed thrombocytopenia associated with dialysis treatments. Laboratory values revealed a platelet count of 50,000 or less postdialysis, with recovery of platelet count during her interdialytic period. An extensive work up including infectious serology and heparin-induced thrombocytopenia test was negative. Based on the pattern of thrombocytopenia and negative work-up, it is concluded that her thrombocytopenia was due to her dialysis treatments. We discuss the literature on thrombocytopenia and hemodialysis and postulate that our patient had a reaction to her dialyzer membrane or to the electron beam radiation method used to sterilize her dialyzer.     

碳化硅陶瓷膜在油水分离中的应用研究

以孔径为0.1μm的碳化硅陶瓷膜,在跨膜压差0.2MPa、温度20℃、伴有固定时间间隔的反冲洗浓排条件下,通过死端过滤处理含油废水.结果表明,膜通量大,出水质量满足<碎屑岩油藏注水水质推荐指标及分析方法>标准(SY/T-532994)的要求,可以作为回注水;且膜简易清洗后,通量可100%恢复.     

膜的污染及其清洗

综述了膜污染的机理及其影响因素，膜的清洗方法及常用的清洗剂，然后根据这些原则清洗中空纤维膜超滤红霉素板框滤液引起的膜污染，得到适合该情形的好的清洗剂，只须用三种化学清洗剂交替清洗，结合清洗技巧，很快膜通量恢复，实验重复性好。本文的清程序和方法可指导膜过滤过程膜污染的清洗。     

用于膜蒸馏苦咸水淡化的PTFE疏水膜实验研究

利用目前国内生产的PTFE疏水膜,以自来水、盐水溶液作工质进行了多层并接气隙式膜蒸馏实验,比较了几种膜的分离性能,研究了料液温度、料液流量、浓度对膜渗透通量的影响,各种膜的通量稳定性及污染情况.实验结果表明:4#膜在长期自来水、盐水实验中通量、电导率都较稳定,特别是在后期实验中,通量最大;而孔径大、涂层薄的1#膜在前期实验中通量较大,而随运行时间增长,通量有所下降,特别是盐水实验中,截留率低,电导率高,因此不适合淡化苦咸水用,综合来看4#膜性能较好.实验后各种膜表面的污染情况较严重,都有黄色沉积物.     

旋转切向入流对膜蒸馏通量的影响

研究了三向旋转切向入流对膜蒸馏的通量的影响,其中讨论了喷嘴形状、进水管与所在圆周中心距离、喷嘴前端距膜面距离、喷嘴与热容腔半径方向之间夹角、喷嘴与进水管之间夹角等膜组件结构参数对膜通量的影响.实验结果发现,可以通过调节这些参数来改变膜通量.     

发动机进气系统高通量富氧膜的研制

采用交联改性的方法对较低分子量的乙烯基硅橡胶进行了改性研究,制备了高通量的富氧膜,结合单因素实验法和Design-expert正交实验设计,考察了原料配比、交联反应时间、固化温度和固化时间等因素对富氧膜性能的影响,确定了最佳富氧性能膜的制备条件:原料配比4.3,反应时间2.15h,固化温度86.25℃,固化时间1.75h;获得了富氧浓度为28.68%,透气量为4696.33 barrer的富氧膜,该膜的富氧浓度与常规商品化膜相当,透气量为常规商品化膜的2~4倍,有应用于发动机富氧进气系统的前景。通过扫描电镜检测、机械性能检测等手段对复合膜进行了进一步表征。     

Calixarene-based photoresponsive ion carrier for the control of Na flux across a lipid bilayer membrane by visible light

A photoresponsive ion carrier based on calix[4]arene was synthesized for the control of Na⁺ flux across lipid bilayer membranes by visible light. Calix[4]arene was chosen as a basic skeleton of a photoresponsive ion carrier because its ether derivatives are known to act as Na⁺ ion carriers in lipid bilayer membranes. For the synthesis of a photoresponsive carrier, dimethylaminoazobenzene was introduced as a photochromic moiety to an ether derivative of p-tert-butylcalix[4]arene. The ion transport ability of the dimethylaminoazobenzene appended calix[4]arene was examined by using a voltage-clamp method. When the calix[4]arene derivative was incorporated into a planar lipid bilayer membrane which separated two chambers filled with 100 mM of NaCl solutions, membrane currents resulting from Na⁺ flux were observed under applying external voltages between two chambers. The concentration dependence of the calix[4]arene derivative on the membrane currents indicated the formation of a 1:1 complex with Na⁺ ions for the calix[4]arene-mediated ion transport across the lipid bilayer membrane. By using visible light (> 400 nm), Na⁺ flux across lipid bilayer membranes containing the dimethylaminoazobenzene appended calix[4]arene derivative could be controlled.