Abstract
Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a mechanical system that provides rapid and short-term support for patients with cardiac failure. In many patients, pulmonary function is also impaired, resulting in poorly-oxygenated cardiac outflow competing against well-oxygenated VA-ECMO outflow, a condition known as North-South syndrome. North-South syndrome is a primary concern because of its potential to cause cerebral hypoxia, which has a critical influence on neurological complications often seen in this patient population. In order to reduce ischemic neurological complications, it is important to understand how clinical decisions regarding VA-ECMO parameters influence blood oxygenation. Here, we studied the impacts of flow rate and cannulation site on oxygenation using a one-dimensional (1D) model to simulate blood flow. Our model was initially tested by comparing blood flow results to those observed from experimental work in VA-ECMO patients. The 1D model was combined with a two-phase flow model to simulate oxygenation. Additionally, the influence of various other clinician-tunable parameters on oxygenation in the common carotid arteries (CCAs) were tested, including, blood viscosity, cannula position within the insertion artery, heart rate, and systemic vascular resistance (SVR), as well as geometrical changes such as arterial radius and length. Our results indicated that blood oxygenation to the brain strongly depended on the cannula insertion site and the VA-ECMO flow rate with a weaker but potentially significant dependence on arterial radius. During femoral cannulation, VA-ECMO flow rates greater than ~4.9L/min were needed to perfuse the CCAs. However, axillary and central cannulation began to perfuse the CCAs at significantly lower flow (~1L/min). These results may help explain the incidence of cerebral hypoxia in this patient population and the common need to change cannulation strategies during treatment to address this clinical problem. While this work describes patient-averaged results, determining these relationships between VA-ECMO parameters and cerebral hypoxia is an important step towards future work to develop patient-specific models that clinicians can use to improve outcomes.
Original language | English |
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Article number | 109707 |
Journal | Journal of Biomechanics |
Volume | 104 |
DOIs | |
State | Published - May 7 2020 |
Funding
Research reported in this publication was supported by the Office of the Director, National Institutes Of Health under Award Number DP5OD019876. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Support was provided by the Big Data-Scientist Training Enhancement Program (BD-STEP) of the Department of Veterans Affairs, the Hartwell Foundation, and Duke Morton H. Friedman Fellowship. We thank Duke OIT for their help with the Duke Compute Cluster runs.
Funders | Funder number |
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National Institutes of Health | |
NIH Office of the Director | DP5OD019876 |
NIH Office of the Director | |
Office of the Director | |
U.S. Department of Veterans Affairs | |
Hartwell Foundation |
Keywords
- 1D blood flow
- Computational fluid dynamics
- ECMO
- Hemodynamics
- Mixing zone