| [ Summary ] |
Pressure drop of blood and dialysate streams at a countercurrent manner induces internal filtration/backfiltration in commercially available dialyzers. When there is less net filtration of the dialyzer, filtration from the blood to the dialysate, through the membrane occurs in the upper stream of the blood flow and backfiltration from the dialysate to blood in the downstream. Internal filtration/backfiltration depends on membrane permeability and the dialyzer specifications. In order to increase the solute clearance, several types of dialyzers designed to enhance internal filtration have been introduced for clinical applications. In these dialyzers, enhanced internal filtration increased convective transport of the solute in addition to diffusive transport. As seen in an analytical study, the flow rate of internal filtration (QIF) was strongly affected by the inner diameter (D), effective length (Leff), and density ratio (FDR) of the hollow fibers. Solute clearance, especially in larger molecular weight solutes, was increased with QIF values. Development of a dialyzer with enhanced internal filtration, however, should take the patient's safety into account, and hemolysis and endotoxin invasion from the dialysate back to the patient should be avoided. |