Numerical calculation of hemolysis levels in peripheral hemodialysis cannulas

Hemolysis in extracorporeal life support systems presents an underestimated problem. In this article, we investigate the hemolytic potential of peripheral hemodialysis cannulas numerically. An axisymmetrical finite element model of 3 cannula sizes was built (13G, 14G, and 16G) that was refined sufficiently in the vicinity of the cannula tip to compute accurately scalar shear stresses. Scalar shear stresses were utilized in Giersiepen's equation to calculate the red blood cell damage (RBD) along streamlines. The streamlines were chosen such that they bound a percentage of the blood flow through the cannula. By integration of the RBD results, the total damage of the cannula was determined and expressed in modified index of hemolysis for comparison with published results. Calculated RBD was overestimated by Giersiepen's equation. The ranking of the cannulas according to their hemolytic potential was preserved. This indicates that power-law equations may be suited for hemolysis prediction of laminar flow devices.