A Lengthwise Examination of Dyed Hemofilter Membrane Tubes for Flow Distribution

Abstract

Hemofilters are used in hemodialysis for critical blood purification. However, hemofilters usually operate at about half the blood flow as hemodialyzers, which may affect the blood-flow distribution within the blood side of the hemofilters and possibly result in an uneven distribution. If the blood-flow distribution is uneven, then it is possible that the filtration flow rate around the many hollow fibers may also be uneven. This research examines the blood-flow distribution of two hemofilters (Excelflo and Hemofeel) using a viscous dye solution instead of blood. Ten long hollow fibers were removed from five different locations within the filters. These individual fibers were then cut lengthwise and the insides of the fibers were examined for their color-concentration distribution. A difference in the color concentration between the two filters was discovered inside of the fibers, indicating that a difference in blood-flow distribution did exist. Furthermore, we also learned that the length and direction of the hollow fibers in the two filters produced a difference in the color-concentration patterns, also indicating a difference in the filtration flow distribution. This research suggests that it is possible to analyze flow distribution in hemofilters with dyes and that the arrangement of the hollow fibers also affects the distribution of the filtration flow.