Abstract
Hemodialysis catheters are used to support blood filtration, yet there are multiple fundamentally different approaches to catheter tip design with no clear optimal solution. Side-holes have been shown to increase flow rates and decrease recirculation but have been associated with clotting/increased infection rates. This study investigates the impact of changing the shape, size and number of side-holes on a simple symmetric tip catheter by evaluating the velocity, shear stress and shear rate of inflowing blood. A platelet model is used to examine the residence time and shear history of inflowing platelets. The results show that side-holes improve the theoretical performance of the catheters, reducing the maximum velocity and shear stress occurring at the tip compared to non-side-hole catheters. Increasing the side-hole area improved performance up to a point, past which not all inflow through the hole was captured, and instead a small fraction slowly ‘washed-out’ through the remainder of the tip resulting in greater residence times and increasing the likelihood of platelet adhesion. An oval shaped hole presents a lower chance of external fibrin formation compared to a circular hole, although this would also be influenced by the catheter material surface topology which is dependent on the manufacturing process. Overall, whilst side-holes may be associated with increased clotting and infection, this can be reduced when side-hole geometry is correctly implemented though; a sufficient area for body diameter (minimising residence time) and utilising angle-cut, oval shaped holes (reducing shear stress and chances of fibrin formation partially occluding holes).
Highlights
Hemodialysis is the process by which blood is removed via a dialysis catheter situated in the right atrium or superior vena cava (SVC), filtered externally, resupplied back into the bloodstream through the same catheter
This study aims to investigate the impact of different side-hole configurations on the local hemodynamics and catheter performance through several computational fluid dynamic (CFD) studies
As flow patterns through the sideholes were consistent across almost all configurations, velocity contours along the centreline for a representative sample of the tip designs are shown in Fig 6 with contours of the remainder available in the supplementary data
Summary
Hemodialysis is the process by which blood is removed via a dialysis catheter situated in the right atrium or superior vena cava (SVC), filtered externally, resupplied back into the bloodstream through the same catheter. Chronic kidney disease (CKD) affects an estimated 15% of adults in the USA [1], with more than 726,000 receiving dialysis [2]. CFD of hemodialysis catheter side-holes of dialysis catheters and were involved in the initial conception of the study but were not involved in the data collection or analysis nor drafting of the manuscript and decision to publish. Additional funding was provided to D.G.O. by the Engineering and Physical Sciences Research Council (EPSRC) Grant EP/N509590/1
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