Heparin as an anticoagulant for the dielectric measurement of blood

Testing blood ex-vivo allows physicians to gain an understanding of what is happening within the human body. Once blood is extracted from the body, it begins to clot. This process can affect the outcome of blood tests, particularly for dielectric measurements. As a result, the dielectric measurements recorded are dependent on time after extraction. To solve the clotting problem, and to allow measurements at any time, anticoagulants are employed. However, a number of anticoagulants have been shown to greatly alter the dielectric properties of fresh blood. In this paper, we analyze the anticoagulant heparin, which works by a different mechanism to stop coagulation than other previously studied anticoagulants. Specifically, heparin acts as a cofactor, accelerating the natural anticoagulation process by several orders of magnitude rather than chelating with clotting factors. We compare intra-individually the dielectric measurements of pure and heparin blood samples at 37°C, taken from four healthy adult volunteers. We also compare the heparin results to previous data on other anticoagulants, specifically, ethylene diamene tetra acetic acid (EDTA) and sodium citrate. In this exploratory study, we found that the effects of heparin on blood are 2.66% or less for the relative permittivity and conductivity, and that heparin has the least effect on dielectric measurements when compared to the other commonly used anticoagulants. These results suggest heparin as the anticoagulant of choice for dielectric measurement.