| [ Summary ] |
The Diffusive performance of hemodialyzers should change with changes in blood flow rates (QB) and/or dialysate flow rates (QD). It is caused not only because the amount of blood which needs to be treated by the dialyzer changes, but also because the overall mass transfer-area coefficient (K0A) changes with QB and/or QD. This effect may be estimated by computing film mass transfer coefficients, which can be done by using various experimental equations reported in literature. It is still useful to perform a calculation of clearance (CL) changes by changing QB and/or QD, assuming K0A to be constant. With this simulation, it can be easily shown that CL cannot exceed the smallest value of QB, QD, K0A and must be equal to by far the smallest of the three, if any. It could also be possible to obtain a better prediction, employing K0A as a function of QB, QD and other necessary parameters. However, even with such efforts, it is very difficult to predict a change in the effective area A, which precludes us from predicting a real number for clearance, when module design, blood or dialysate flow rates are changed. |