Dean vortices: a comparison of woven versus helical and straight hollow fiber membrane modules

Computational Modeling of Effects of Mechanical Shaking on Hemodynamics in Hollow Fibers

Introduction:

Blood-membrane interaction during hemodialysis develops a secondary protein layer on the dialysis membrane surface, resulting in reduction of hemodialyzer performance. Wall shear stress at the surface of the hollow-fiber membrane is one of the determinant factors able to influence dialysis efficiency. Shaking of hemodialyzer during treatment could increase the wall shear stress of the membrane, which could enhance hemodialyzer performance.

Methods:

In this study, hemodynamic changes in hollow fibers were analyzed using computational fluid dynamics software for various shaking conditions of hemodialyzer (longitudinal, transverse, rotational motions).

Results:

Longitudinal motion induced reverse flow, while transverse motion induced symmetric swirling inside the hollow fiber. During rotational motions, nonuniform vortices were developed according to the rotational radius of the hollow fiber. These changes in flow pathlines induced by different shaking profiles increased the relative motion of blood, transmembrane pressure, and wall shear stress on dialysis membrane surfaces. Both longitudinal and transverse shaking profiles showed a linear relationship between shaking velocity (the product of amplitude and frequency) and wall shear stress.

Conclusion:

Performance of hemodialyzer can be enhanced with simple mechanical shaking motions, and optimal shaking profiles for clinical application can be investigated and predicted with the computational fluid dynamics model proposed in this study.