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In Vitro Model of Physiological and Pathological Blood Flow with Application to Investigations of Vascular Cell Remodeling
Published on: November 3, 2015
Viscoelasticity of pediatric blood and its implications for the testing of a pulsatile pediatric blood pump
Jennifer A Long1, Akif Undar, Keefe B Manning
1Department of Bioengineering, The Pennsylvania State University, University Park, PA 16802, USA.
Insights
Pediatric blood viscosity and elasticity were measured, revealing similar viscoelastic properties to adult blood. These findings inform the development of pediatric blood pumps using viscoelastic analogs.
Area of Science:
- Biomedical Engineering
- Hemodynamics
- Rheology
Background:
- Blood rheology, including viscosity and elasticity, is crucial for understanding blood flow, particularly in medical devices like pulsatile blood pumps.
- Previous research has focused on blood viscosity, but the elasticity of pediatric blood remains largely uncharacterized, hindering device design.
- The viscoelastic properties of blood significantly impact flow dynamics within small blood pumps, affecting filling characteristics and flow separation.
Purpose of the Study:
- To measure and characterize the viscosity and elasticity of pediatric blood across a range of hematocrit values.
- To compare the viscoelastic properties of pediatric blood with adult blood.
- To develop pediatric blood analog solutions based on measured properties for use in blood pump testing.
Main Methods:
- Utilized an oscillatory rheometer to measure blood viscosity and elasticity against shear rate.
- Tested pediatric blood samples with hematocrit levels ranging from 19% to 56%.
- Statistically analyzed data to compare pediatric and adult blood viscoelasticity at constant hematocrit.
Main Results:
- Presented comprehensive data on pediatric blood viscosity and elasticity as a function of shear rate and hematocrit.
- Found minimal influence of patient age on blood viscoelasticity.
- Demonstrated statistically similar viscoelastic properties between adult and pediatric blood when compared at constant hematocrit.
Conclusions:
- Pediatric blood exhibits viscoelastic properties comparable to adult blood.
- Developed validated blood analog solutions for pediatric hematocrit levels.
- These findings are essential for optimizing the design and performance of pediatric blood pumps by incorporating realistic viscoelastic fluid behavior.
Abstract:
Red blood cell hematocrit, aggregation and deformability, and plasma protein concentration influence the viscosity and elasticity of whole blood. These parameters affect the flow properties, especially at low shear rates (< 50 s(-1)). In particular, we have previously shown that the viscoelasticity of fluid affects the inlet filling characteristics and regions of flow separation in small pulsatile blood pumps. Although the viscosity of pediatric blood has been thoroughly studied, its elasticity has not been previously measured. Here we present the viscosity and elasticity of pediatric blood against shear rate for hematocrits from 19-56, measured using an oscillatory rheometer. There is little effect of patient age on blood viscoelasticity. A statistical analysis showed that when compared at constant hematocrit, blood from adult and pediatric patients had similar viscoelastic properties. We present blood analog solutions, as a function of hematocrit, constructed on the basis of the pediatric measurements. Flow field results for viscoelastic analogs of 20, 40 and 60% hematocrit and a Newtonian analog will be compared in the initial, in vitro testing of the Penn State pediatric blood pump, to determine the importance of incorporating a viscoelastic analog into the desigh interaction.
