Background: Research on hemorheology is driven in part by its significance in blood diseases and the possible use of hemorheology as a diagnostic tool. However, existing data on blood rheology are limited largely to measurements of steady shear behavior often with varying measurement protocols and insufficient characterization of the physiology.
Objective: The effects of ex vivo aging and environmental conditions on blood viscosity are investigated to improve standards for hemorheology measurements.
Methods: Measurements on the viscosity of blood from nine healthy donors are obtained and the physiological state of the blood determined. Steady and transient shear measurements are reported as a function of time from withdrawal. The effect of transportation temperature is also assessed.
Results: Blood transported at 4 °C may exhibit anomalous viscosity variations for short to intermediate times, as opposed to blood transported at room temperature. A time of approximately 3.0 hours was identified as the maximum time after the initial test that accurate rheological tests can be conducted on blood samples.
Conclusions: Measurement protocol and time limit guidelines are established for conducting accurate rheological measurements on blood.
Keywords: Hemorheology; aging; hyperviscosity; measurement protocol; thixotropy.