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LIF study of mixing in a model of a vein punctured by a cannula

Borg, Andreas and Fuchs, Laszlo LU (2002) In International Journal of Heat and Fluid Flow 23(5). p.664-670
Abstract
Steady flow and mixing in a model of an "arterialized" vein punctured by a cannula as occurs during hemodialysis has been investigated in vitro. The motivation is that a major cause of vascular access dysfunction is the development of venous stenoses. This phenomenon lacks physiological explanation. However, one may attribute this quick process to the chemical content of the dialyzed blood and its flow near the point of infusion. The interest in mixing of chemical compounds in the dialyzed blood supplied through the cannula is, therefore, genuine due to the clinical impacts of haemodyalysis. We are interested in understanding the mixing of the two streams; namely, the untreated blood through the vein and the treated blood through the... (More)
Steady flow and mixing in a model of an "arterialized" vein punctured by a cannula as occurs during hemodialysis has been investigated in vitro. The motivation is that a major cause of vascular access dysfunction is the development of venous stenoses. This phenomenon lacks physiological explanation. However, one may attribute this quick process to the chemical content of the dialyzed blood and its flow near the point of infusion. The interest in mixing of chemical compounds in the dialyzed blood supplied through the cannula is, therefore, genuine due to the clinical impacts of haemodyalysis. We are interested in understanding 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. In addition, since the blood contains molecules of widely different diffusivity properties, the local composition of blood near the point of injection is of interest. The hypothesis is that concentration non-uniformities may lead to undesired chemical or bio-chemical reactions leading to the pathological 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 laser induced fluorescence (LIF). 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. We have further considered the effect of rotating the cannula. This leads to a significant change in the mixing process. The significance of the non-uniformities in mixing of solvents in the blood for the development of venous stenoses should be further studied not only in fluid dynamical terms but also in terms of endothelial (cellular) effects. (C) 2002 Published by Elsevier Science Inc. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
International Journal of Heat and Fluid Flow
volume
23
issue
5
pages
664 - 670
publisher
Elsevier
external identifiers
  • wos:000176511800014
  • scopus:0036779268
ISSN
0142-727X
DOI
10.1016/S0142-727X(02)00162-5
language
English
LU publication?
yes
id
0d100de8-41c0-4106-99de-faacc5e01e8e (old id 334540)
date added to LUP
2007-08-10 14:21:24
date last changed
2017-01-01 04:49:01
@article{0d100de8-41c0-4106-99de-faacc5e01e8e,
  abstract     = {Steady flow and mixing in a model of an "arterialized" vein punctured by a cannula as occurs during hemodialysis has been investigated in vitro. The motivation is that a major cause of vascular access dysfunction is the development of venous stenoses. This phenomenon lacks physiological explanation. However, one may attribute this quick process to the chemical content of the dialyzed blood and its flow near the point of infusion. The interest in mixing of chemical compounds in the dialyzed blood supplied through the cannula is, therefore, genuine due to the clinical impacts of haemodyalysis. We are interested in understanding 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. In addition, since the blood contains molecules of widely different diffusivity properties, the local composition of blood near the point of injection is of interest. The hypothesis is that concentration non-uniformities may lead to undesired chemical or bio-chemical reactions leading to the pathological 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 laser induced fluorescence (LIF). 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. We have further considered the effect of rotating the cannula. This leads to a significant change in the mixing process. The significance of the non-uniformities in mixing of solvents in the blood for the development of venous stenoses should be further studied not only in fluid dynamical terms but also in terms of endothelial (cellular) effects. (C) 2002 Published by Elsevier Science Inc.},
  author       = {Borg, Andreas and Fuchs, Laszlo},
  issn         = {0142-727X},
  language     = {eng},
  number       = {5},
  pages        = {664--670},
  publisher    = {Elsevier},
  series       = {International Journal of Heat and Fluid Flow},
  title        = {LIF study of mixing in a model of a vein punctured by a cannula},
  url          = {http://dx.doi.org/10.1016/S0142-727X(02)00162-5},
  volume       = {23},
  year         = {2002},
}