Current Directions in Biomedical Engineering (2018-09-01)

In silico study of the dynamic interaction between extracorporeal circulation and native circulation

  • Bongert Markus,
  • Gehron Johannes,
  • Geller Marius,
  • Böning Andreas,
  • Grieshaber Philippe

DOI
https://doi.org/10.1515/cdbme-2018-0014
Journal volume & issue
Vol. 4, no. 1
pp. 55 – 58

Abstract

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An in silico investigation of modelled Extracorporeal Life Support (ECLS) via a femoral arterial cannula revealed the existence of both a defined separation zone between the opposing flows (ECLS, native flow) and different ranges dependent on flow distribution. The interaction between pulsating native circulation and constant ECLS flow is dynamic. A transient simulation model was developed to investigate the dynamic influence on this fluid mechanical interaction. The in silico model is based on a CT-generated 3D model derived from a life-sized silicon aorta. A geometric standard cannula (16Fr) is inserted femoral. Inlet boundary conditions such as the temporal flow profile of a subject from the left ventricle (native circulation) and the flow from the femoral cannula are varied such that during transient simulations the summed flow (total perfusion) is 5.5 l/min. The outlet pressure boundary conditions at the branching arteries are selected such as to model the downstream vascular system. Transient simulations revealed the dynamic effects of different flow fractions (Heart - ECLS) on the flow. Stationary simulations show a separation zone between the two flows, the position of which respectively the ECLSrange, oscillates dependent of the native circulation. Furthermore, it was noted that a raised pulse was impedimental to ECLS. This can be partly compensated by increasing the length of cannula inserted. At the same time the ECLS supply for the brain can improve at the cost of performance post-bifurcation. Increasing the ECLS fraction to above 50% flow led to retrograde flow combined with blood suction from the femoral artery. The EMPAC project model has been further developed to include investigation of the dynamic effects of blood flow. This has made it possible for the first time to analyse in detail and evaluate the temporal effects of both opposing flows streams. A subsequent investigation explains whether aortic elasticity plays a significant role.

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