Leypoldt J K, Schmidt B, Gurland H J
Nephrology Department, Klinikum Grosshadern, University of Munch, FRG.
Blood Purif. 1991;9(2):74-84. doi: 10.1159/000170000.
A method for determining local transmembrane fluid movement in a commercial hemodialyzer at low dialysate flow rates by measuring changes along the dialyzer length in the local concentration of a marker macromolecule added to the dialysis solution has been developed. The method was evaluated in vitro at zero net ultrafiltration using dialyzers containing polysulfone (n = 4) and cuprophane (n = 3) membranes. The local concentration of the marker macromolecule along the dialyzer length was higher than the input dialysate concentration only during experiments with dialyzers containing polysulfone membranes. These observations provide direct empirical evidence that fluid movement in the dialysate to blood direction, i.e., backfiltration, occurs during hemodialysis with this highly permeable membrane. Net rates of backfiltration for the dialyzer containing polysulfone membrane were also calculated from changes in the local concentration of the marker macromolecule and mass balance considerations. The calculated backfiltration rates increased with increasing blood flow rate and trended upward with increasing dialysate flow rate. The described methodology provides a novel approach for the further characterization of fluid and solute transport during hemodialysis with highly permeable membranes.
已开发出一种方法，通过测量添加到透析液中的标记大分子局部浓度沿透析器长度的变化，来确定商用血液透析器在低透析液流速下的局部跨膜流体运动。使用含有聚砜膜（n = 4）和铜仿膜（n = 3）的透析器，在零净超滤的体外条件下对该方法进行了评估。仅在使用含有聚砜膜的透析器进行实验时，标记大分子沿透析器长度的局部浓度才高于输入透析液浓度。这些观察结果提供了直接的经验证据，表明在使用这种高渗透性膜进行血液透析期间，透析液向血液方向的流体运动，即反滤过发生。还根据标记大分子局部浓度的变化和质量平衡考虑因素，计算了含有聚砜膜的透析器的反滤过净速率。计算出的反滤过速率随血流速率的增加而增加，并随透析液流速的增加而呈上升趋势。所描述的方法为进一步表征使用高渗透性膜进行血液透析期间的流体和溶质转运提供了一种新方法。
