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ISSN オンライン: 2642-0554

QUANTITATIVE VISUALIZATION OF MIXING IN A MODEL OF AN ARTERIALIZED VEIN PUNCTURED BY A CANNULA

Andreas Borg
Division of Fluid Mechanics Lund Institute of Technology Box 118, 221 00 Lund

Laszlo Fuchs
Department of Mechanics, KTH, CICERO, SE-10044 Stockholm; Division of Fluid Mechanics Lund University Lund, 22363, Sweden

要約

Steady flow and mixing in a model of an "arterialized" vein punctured by a cannula as occur during hemodialysis are investigated in vitro. The motivation is that a major cause of vascular access dysfunction is the development of venous stenoses. The interest in mixing of chemical compounds in the dialyzed blood supplied through the cannula is genuine due the clinical impacts of haemodialysis. One is interested also in the mixing of the two streams; namely the untreated blood through the vein and the treated blood through the cannula. This mixing affects the local pH, which in turn can affect the solubility of several salts used for dialysis. This may lead to undesired chemical or bio-chemical processes in the region around the needle.
The mixing of a high Schmidt number substance in the stream entering from the cannula with the base flow in the vein is studied by LIF (Laser Induced Fluorescence). The investigations are performed for a range of typical Reynolds numbers in the cannula and the vein found during hemodialysis.
The study shows complicated mixing patterns around the cannula, and that non-uniformities in the blood persist over long distances for the lower flow rates found in vivo. For the higher flow rates, the flow loses its stability and mixing is enhanced. The nature of this instability is shown, and quantitative data of concentration fluctuations are given. If these mixing patterns are of significance for the development of venous stenoses, they should be possible to link them to the development of lesions.