Einfacher und sicherer Austausch von Komponenten in extrakorporalen Blutkreisläufen

• Simple and safe exchange of components of extracorporeal blood circuits

Wagner, Georg; Steinseifer, Ulrich (Thesis advisor); Jacobs, Georg (Thesis advisor)

Düren : Shaker Verlag (2021)
Book, Dissertation / PhD Thesis

In: Aachener Beiträge zur Medizintechnik 64
Page(s)/Article-Nr.: XII, 139 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2020

Abstract

Extracorporeal systems are among the most sophisticated therapeutic options because they carry the patient's blood outside the body. The special properties of blood, such as the coagulation system, place high demands on the systems. In about 80 % of long-term applications, a component fails and must be replaced. Current procedures for replacement are in need of optimization for patients and users. Therefore, it should be investigated whether a procedure can be created to enable a simple, fast and safe exchange. The analysis of the currently described procedures and the user requirements shows that a new technical solution is needed. Simplicity of exchange is seen as a central demand, leading to increased security on several levels. Using the design methodology, several concepts are created and evaluated, and the best one is used for validation in a laboratory model. The operating forces are a critical aspect, they are mainly caused by the friction of the seals. In the case of elastomers, nonlinear aspects and complex interdependencies play a critical role, making it impossible to make a prediction from existing data that is close to the application. Own investigations on different material pairings regarding the required contact stresses and the resulting frictional forces show that the contact pressures and forces required here are only about 10 % of those normally used. The laboratory model designed in this way is used to test the sealing concept and hemocompatibility. Areas with increased risk of thrombosis are identified by CFD and validated by PIV. Blood tests show that hemolysis is very low. The time required for replacement can be greatly reduced. In addition, the leakage that occurs and the amount of air introduced are very low. In the optimized design, the gained knowledge on the design of the flow path is implemented and the effectiveness is shown by means of CFD. Finally, the fulfillment of the requirements is evaluated.