How to Evaluate Hemolysis Risk in Medical Devices using Ansys CFD

Good morning, good afternoon, everybody, depending on where you are, or good night, good evening. Thank you for being here today. My name is Jesus Ramirez, Technical Leader of the CFD team at Austin Engineering.

Today, I'm going to talk about how we can use ANSYS CFD to evaluate hemolysis risk in medical devices. Let me show you what I am planning to talk about. Initially, I will give a brief introduction of our company, Austin Engineering, and what hemolysis is, and its impact on patient health.

Then, I will provide an overview of CFD and its applications in hemolysis analysis, and how to select an appropriate blood model for CFD simulation. In the end, I will do a live demo to show you how to set up a basic hemolysis analysis using ANSYS CFD, specifically using some CCFX.

Austin Engineering is an ANSYS lead channel partner, and we have expertise in simulation of structural, thermal, fluid, and electromagnetic fields. We help customers not only with software but also with consulting projects, training, mentorships, or technical support.

Our business is all related to simulation, and we work with different physics, including CFD, structures, electronics, optics, photonics, 3D design analysis, semiconductor, acoustic simulations, and many others.

Hemolysis is a condition that may occur due to various factors, including certain diseases, medications, or improper use of medical devices. Mechanical hemolysis, caused by the blood flowing through a medical device or machine at high velocities or pressures, is the focus of this presentation.

Mechanical hemolysis can cause red blood cells to break, leading to hemolysis. Medical devices that can generate hemolysis if not used properly include blood collection devices, IV catheters, and hemodialysis machines.

High blood flow rates in hemodialysis machines and oxygenators can cause high shear stresses, leading to mechanical hemolysis. CFD can predict the shear stress region, allowing us to predict where hemolysis may occur and its severity.

By optimizing designs to improve product performance, we can reduce hemolysis risk. In the live demo, I will show you how to set up a hemolysis analysis using ANSYS CFD. We will use the Cason model, one of the most used viscosity models for blood, to characterize the blood.

The Cason model is highly used for blood absorption and is included in our ANSYS tools. To account for the effect of shear rate on the viscosity value for blood flow, we can use the Cason model, the Power Law, the Oswald-Dewelle model, or the Carre model.

These models are included in our ANSYS tools, and we can handle non-Newtonian viscosity models to have a good characterization of the blood.

In the setup, we will create the blood material with non-Newtonian properties and use the k-omega SST model, a RANS turbulence model highly recommended for internal flows.

We will also create an additional variable, the hemolysis index, based on some empirical correlations, and use expressions to account for the shear stress, the main driver for hemolysis.

In the boundary conditions, we will use a developed profile for the inlet velocity and a pressure outlet for the outlet. We will also ensure that the solution is converged and do some post-processing to analyze the results.

By reducing the hemolysis index and increasing the velocity, we can design a medical device that gives the desired flow rate without hemolysis.

We can use design exploration tools, such as the response surface method, to understand how the different variables are correlated and propose some points for optimization.

In summary, using ANSYS CFD, we can evaluate hemolysis risk in medical devices by predicting the shear stress region, optimizing designs to improve product performance, and reducing hemolysis risk.