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Micro-particle Image Velocimetry for Velocity Profile Measurements of Micro Blood Flows
Published on: April 25, 2013
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Blood viscosity in microvessels: experiment and theory
Timothy W Secomb1, Axel R Pries2
1Department of Physiology, University of Arizona, Tucson, AZ 85724, USA.
Comptes Rendus. Physique
|August 5, 2014
Summary
Blood viscosity decreases in narrow tubes due to red blood cell deformation, a phenomenon impacting microvascular flow. In vivo measurements show higher viscosity than in vitro experiments, requiring further theoretical understanding.
Area of Science:
- Biophysics
- Fluid Mechanics
- Hematology
Background:
- Blood exhibits unique flow properties due to its composition as a suspension of deformable red blood cells.
- The Fåhraeus-Lindqvist effect describes the decrease in blood viscosity with decreasing tube diameter.
- Microvessels, where most circulatory resistance occurs, operate within the size range of this effect.
Purpose of the Study:
- To review experimental observations of blood's apparent viscosity in narrow tubes, both in vitro and in vivo.
- To explore the discrepancy between in vitro and in vivo measurements of blood viscosity in microvessels.
- To summarize progress in developing theoretical models for blood flow in microcirculation.
Main Methods:
- Review of experimental data on blood viscosity in glass tubes of varying diameters (10-300 μm).
- Comparison of in vitro (glass tubes) and in vivo (microvessels) blood viscosity measurements.
- Analysis of theoretical approaches to explain the observed viscosity changes.
Main Results:
- Blood's apparent viscosity significantly decreases with tube diameter in vitro, consistent with the Fåhraeus-Lindqvist effect.
- Blood viscosity in microvessels in vivo is substantially higher than predicted by in vitro experiments.
- Red blood cell deformability is a key factor in the observed Fåhraeus-Lindqvist effect.
Conclusions:
- The Fåhraeus-Lindqvist effect is a critical factor in understanding blood flow in narrow tubes.
- Discrepancies between in vitro and in vivo viscosity highlight the complexity of microcirculatory hemodynamics.
- Further theoretical development is needed to fully explain blood flow behavior in microvessels.
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