Philip J L, Jaffrin M Y, Ding L
Department of Biological Engineering, University of Compiegne, France.
J Biomech Eng. 1994 Nov;116(4):514-20. doi: 10.1115/1.2895803.
The use of pulsed blood flow in membrane plasmapheresis permits enhancement of plasma filtration yet may result in high levels of hemolysis due to large increases in instantaneous transmembrane pressure (TMP). This work investigates the occurrence of hemolysis as a function of TMP and wall shear rates (gamma w) for both steady and pulsed blood flow conditions. Two types of hollow fiber filters with identical polypropylene membranes but different lengths and membrane areas (0.1 and 0.25 m2) were tested. Fresh citrated bovine blood was circulated through the fibers at various blood flowrates and TMP in a single pass circuit using a pulsation generator, made of a single roller peristaltic pump. The free hemoglobin concentration of the plasma, Hbm, was measured from permeate samples collected at each set of TMP and gamma w conditions. It was found that the net hemolysis generated by the filtration was proportional to the membrane area. This justified the introduction of an hemolysis index, IH, equal to the plasma hemoglobin per unit membrane area. The boundary for the occurrence of hemolysis was thus defined by setting IH = 30 mg/dl.m2. For both steady and pulsed flow conditions the hemolysis boundaries were found to be straight lines in the TMP-gamma w plane. They were identical for the two filters under steady flow but different for pulsed flow. At the same time mean wall shear rates hemolysis occurred at a lower time mean TMP under pulsed flow conditions than under steady flow conditions.
在膜血浆置换术中使用脉冲血流可提高血浆过滤效率，但由于瞬时跨膜压力（TMP）大幅增加，可能导致高水平的溶血。这项研究调查了在稳定血流和脉冲血流条件下，溶血发生率与TMP和壁面剪切速率（γw）之间的关系。测试了两种具有相同聚丙烯膜但长度和膜面积不同（0.1和0.25平方米）的中空纤维过滤器。使用由单滚轮蠕动泵制成的脉动发生器，让新鲜的枸橼酸化牛血以不同的血流速率和TMP在单程回路中循环通过纤维。从在每组TMP和γw条件下收集的渗透液样品中测量血浆中的游离血红蛋白浓度Hbm。发现过滤产生的净溶血与膜面积成正比。这证明引入溶血指数IH是合理的，IH等于单位膜面积的血浆血红蛋白。因此，通过将IH = 30 mg/dl·m2设定来定义溶血发生的边界。对于稳定血流和脉冲血流条件，在TMP-γw平面中溶血边界均为直线。在稳定血流条件下，两种过滤器的溶血边界相同，但在脉冲血流条件下不同。同时，在相同的平均壁面剪切速率下，脉冲血流条件下的溶血发生时的时间平均TMP低于稳定血流条件下的时间平均TMP。
