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The physics of red cell sedimentation.
Physics in Medicine and Biology
|February 1, 1985
Summary
Normal red blood cells (erythrocytes) sediment at a constant rate in saline, but this rate varies with concentration. Whole blood exhibits different sedimentation behavior, supporting a theory of energy dissipation in heterogeneous fluids.
Area of Science:
- Biophysics
- Hematology
- Fluid Dynamics
Background:
- Understanding erythrocyte sedimentation is crucial for diagnosing various medical conditions.
- Previous theoretical studies proposed energy dissipation mechanisms in heterogeneous fluids like blood.
Purpose of the Study:
- To experimentally determine the sedimentation rate of normal human erythrocytes in saline.
- To investigate the influence of red blood cell concentration on sedimentation velocity.
- To compare sedimentation behavior in a red cell-saline suspension versus anticoagulated whole blood.
Main Methods:
- Blood samples were collected from healthy volunteers.
- Erythrocytes were isolated, washed, and resuspended in isotonic saline.
- Sedimentation rates were measured over time at varying cell concentrations.
- Sedimentation in anticoagulated whole blood was also analyzed.
Main Results:
- Erythrocyte sedimentation velocity was constant over time for a specific concentration in saline.
- Sedimentation rate showed experimental variation with red cell concentration.
- The 'Svedberg constant' for normal red cells was evaluated by extrapolating to zero concentration.
- Whole blood exhibited significantly different sedimentation rates and variable velocity (acceleration/deceleration) compared to saline suspensions.
Conclusions:
- Experimental data align with continuum physics theory for erythrocyte sedimentation.
- Observed differences in whole blood support the theory of an internal energy dissipative mechanism in heterogeneous fluids.
- This mechanism is proposed to be absent in homogeneous fluids like water.