In this study, the impact of the cannula geometry on the formation of the depot in subcutaneous tissue is investigated when injecting insulin using an insulin pump. The simulations have been conducted using the Computational Fluid Dynamics (CFD) software ANSYS Fluent. The study is focusing on rapid acting insulin analogues typically used in insulin pump therapy, which enter the bloodstream very shortly after administration. A previously developed 2-dimensional simulation has been transferred into a 3-dimensional case in order to simulate cases with non-axisymmetric geometries. The tissue has been modeled as a homogeneous anisotropic porous media by the use of different porosity values in the parallel and perpendicular direction with respect to the skin surface. The process of absorption is implemented into the model by the use of a locally variable species sink term. The basic case, simulated with a solid cannula, has been compared to other cannula geometries in order to evaluate if the delivery of insulin in the tissue can be improved. The geometries under consideration are the addition of circumferential holes in the wall of the cannula as well as using an array of cannulas instead of a single cannula. The depot formation is analyzed simulating a standard bolus injection of 0.05ml of insulin using an injection time of 25 seconds. It is observed that the addition of multiple holes in the wall of the cannula or using an array of cannulas can alter the shape of the depot quite significantly. The impact of the depot shape on the diffusion of insulin in the tissue has been evaluated by measuring the total volume of the depot after injection.

This content is only available via PDF.
You do not currently have access to this content.