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Effect of plasma expander viscosity on the cell free layer
C Makena Hightower1, Ozlem Yalcin, Beatriz Y Salazar Vázquez
1Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA. cmhighto@ucsd.edu
Biorheology
|August 4, 2011
Summary
Low and high viscosity plasma expanders affect the cell-free layer (CFL) width in rat microcirculation. Higher viscosity expanders, like Hetastarch, result in a smaller CFL increase compared to lower viscosity expanders such as human serum albumin.
Area of Science:
- Physiology
- Microcirculation research
- Hemodynamics
Background:
- The cell-free layer (CFL) is a plasma-rich region near the vessel wall in microcirculation.
- Understanding CFL dynamics is crucial for predicting blood flow and oxygen delivery.
- Plasma expanders are used to manage blood volume but can alter blood rheology.
Purpose of the Study:
- To investigate the impact of low and high viscosity plasma expanders on CFL width.
- To analyze the effects of hemodilution with specific plasma expanders on microvascular parameters.
- To determine the relationship between plasma expander viscosity and CFL changes.
Main Methods:
- Hemodilution (40% blood volume) using 5% human serum albumin (HSA) or 6% Hetastarch in Sprague-Dawley rats.
- Microcirculation analysis in exteriorized cremaster muscle arterioles.
- Measurement of mean arterial pressure, heart rate, flow velocity, and CFL width at various time points.
- Determination of blood and plasma viscosity from terminal blood samples.
Main Results:
- Both HSA and Hetastarch hemodilution significantly increased CFL width, pseudoshear rate, diameter, and flow.
- Peripheral vascular resistance decreased post-hemodilution.
- The increase in CFL width was significantly greater with HSA compared to Hetastarch.
- Hetastarch led to a significant increase in blood and plasma viscosity compared to HSA.
Conclusions:
- Plasma expander viscosity significantly influences CFL width in microcirculation.
- Lower viscosity expanders (HSA) induce a greater increase in CFL width than higher viscosity expanders (Hetastarch).
- The observed effects are proportional to the molecular weight of the colloids in the plasma expander solutions.
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