Flow Dynamics and Mixing in Extracorporeal Support: A Study of the Return Cannula

Abstract

Cannulation strategies in medical treatment such as in extracorporeal life support along with the associated cannula position, orientation and design, affects the mixing and the mechanical shear stress appearing in the flow field. This in turn influences platelet activation state and blood cell destruction. In this study, a co-flowing confined jet similar to a return cannula flow configuration found in extracorporeal membrane oxygenation was investigated experimentally. Cannula diameters, flow rate ratios between the jet and the co-flow and cannula position were studied using Particle Image Velocimetry and Planar Laser Induced Fluorescence. The jet was turbulent for all but two cases, in which a transitional regime was observed. The mixing, governed by flow entrainment, shear layer induced vortices and a backflow along the vessel wall, was found to require 9–12 cannula diameters to reach a fully homogeneous mixture. This can be compared to the 22–30 cannula diameters needed to obtain a fully developed flow. Although not significantly affecting mixing characteristics, cannula position altered the development of the flow structures, and hence the shear stress characteristics.

Numerical and experimental investigation of a lighthouse tip drainage cannula used in extracorporeal membrane oxygenation

“…Two circuits were used: one to drive the vessel flow in the vessel and another for the drainage by the cannula using a centrifugal blood pump. The setup was similar to that used by Lemétayer et al 19 The velocity field measurements were acquired using Particle Image Velocimetry (PIV). Zirconium dioxide particles with a diameter of 5 μm were used as tracers and the system comprised a high‐speed Nd:YAG laser (LPY703 50‐200, Litron Laser, Rugby, England) and a Dantec highspeed double frame CCD camera (Speedsense M120, Dantec Dynamics, Skovlunde, Denmark) with a 105 mm Nikkor lens (Nikkor, Nikkon, Tokyo, Japan).…”

“…In particular, the return cannula produces a flow field that resembles a confined jet where the ratio of vessel to cannula diameter sets the level of confinement. Although confined jets from an engineering perspective are well studied, few fluid‐dynamical studies addressed geometries as confined as found in ECMO cannulation 19 . Regarding the drainage cannula, the flow is characterized by strong shear layers developing in the suction region.…”

“…Although confined jets from an engineering perspective are well studied, few fluid‐dynamical studies addressed geometries as confined as found in ECMO cannulation. 19 Regarding the drainage cannula, the flow is characterized by strong shear layers developing in the suction region.…”

Recirculation in single lumen cannula venovenous extracorporeal membrane oxygenation: A non-randomized bi-centric trial

“…In 2018, Togo et al ( 23 ) showed comparable results in an experimental setting in four goats; in their study, the tip-to-tip distance in femoro-jugular configuration was associated with the R f as assessed with the limited oxygen saturation calculation method. In an experimental model it was recently shown that a distance of nine to twelve cannula diameters was required for the mix of native venous and ECMO blood to become homogenous ( 24 ). Further investigation is necessary with respect to the association of higher Rf with lower heart rate.…”

Patient-Specific Computational Modeling of Different Cannulation Strategies for Extracorporeal Membrane Oxygenation

“…This interplay between pulsatile cardiac and steady-state ECMO flow results in regions involving high shear flows, abnormal pulsatility, and differential perfusion pressures. 14 A thorough understanding of both global and regional blood pressure and flow phenomena in different cannulation configurations will aid in patient-specific decision making in ECMO management.…”