Abstract
PurposeCurrently used cannulae for extracorporeal carbon dioxide removal (ECCO2R) are associated with complications such as thrombosis and distal limb ischemia, especially for long-term use. We hypothesize that the risk of these complications is reducible by attaching hemodynamically optimized grafts to the patient’s vessels. In this study, as a first step towards a long-term stable ECCO2R connection, we investigated the feasibility of a venovenous connection to the common iliac veins. To ensure its applicability, the drainage of reinfused blood (recirculation) and high wall shear stress (WSS) must be avoided.MethodsA reference model was selected for computational fluid dynamics, on the basis of the analysis of imaging data. Initially, a sensitivity analysis regarding recirculation was conducted using as variables: blood flow, the distance of drainage and return to the iliocaval junction, as well as the diameter and position of the grafts. Subsequently, the connection was optimized regarding recirculation and the WSS was evaluated. We validated the simulations in a silicone model traversed by dyed fluid.ResultsThe simulations were in good agreement with the validation measurements (mean deviation 1.64%). The recirculation ranged from 32.1 to 0%. The maximum WSS did not exceed 5.57 Pa. The position and diameter of the return graft show the highest influence on recirculation. A correlation was ascertained between recirculation and WSS. Overall, an inflow jet directed at a vessel wall entails not only high WSS, but also a flow separation and thereby an increased recirculation. Therefore, return grafts aligned to the vena cava are crucial.ConclusionIn conclusion, a connection without recirculation could be feasible and therefore provides a promising option for a long-term ECCO2R connection.
Highlights
Since its first successful application in 1971,19 extracorporeal life support (ECLS, at that time called extracorporeal membrane oxygenation (ECMO)12) has become an established treatment for circulatory and pulmonary support, and a combination thereof.[34]
We investigate the connection of grafts to the common iliac vessels (CIV) for venovenous ECCO2R
We investigated two different scenarios, represented by different blood flows through the grafts: On the one hand, a critical but still acceptable scenario, in which the flow through the grafts is at the upper end Distance to iliocaval junction (IJ)
Summary
Since its first successful application in 1971,19 extracorporeal life support (ECLS, at that time called extracorporeal membrane oxygenation (ECMO)12) has become an established treatment for circulatory and pulmonary support, and a combination thereof.[34]. ECLS was originally a modified cardiopulmonary bypass, the use of which was limited to short-term support only. The longer duration of support with ECLS was facilitated by the simplification of the circuit. The development was mainly caused by the introduction of polymethylpentene (PMP) hollow fiber membranes.[14]. In the last 10–15 years, the application of ECLS has evolved to a mid-term support with awake and spontaneously breathing patients treated in the ICU.[4] Again, this
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