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Effect of whole blood viscosity and red cell mass on canine thromboelastographic tracings

Brooks, Aimee C
http://rave.ohiolink.edu/etdc/view?acc_num=osu1397244092

Abstract Details

2014, Master of Science, Ohio State University, Veterinary Clinical Sciences.
Abnormalities in hemostasis can result in life-threatening bleeding or thrombotic disorders. Whole blood viscoelastic methodologies including thromboelastography (TEG) have become increasingly popular in human and veterinary research and clinical medicine as a means of assessing coagulation. However, the properties of blood that influence these methodologies must be understood to accurately interpret the results, especially when in vitro findings do not match what is expected in vivo. It is well established that the hematocrit (Hct) of a sample influences the TEG tracing. While, clinically, anemia has been shown to result in an increased risk of bleeding, anemic TEG tracings typically have a hypercoagulable appearance. The opposite is also seen, as TEG tracings of samples with high Hct appear hypocoagulable. The reason for this effect of Hct on TEG tracings is unknown. However, as Hct is the main determinant of whole blood viscosity, it is possible the influence of red blood cells on the TEG is truly the effect of viscosity. In order to elucidate this difference, whole blood viscosity must be manipulated separately from Hct. We hypothesized that the effect of Hct on TEG tracings may be due to a mechanical bias of the methodology due to the effect of Hct on blood viscosity, rather than the red blood cells themselves. To test this hypothesis, three experiments were performed. The first used alginate (ALG) to normalize blood viscosity independent of red cell mass at varying hematocrits (45%, 20%, and 10%) and compared to control samples diluted in saline. The second experiment had a similar design, but used a different agent, carboxymethylcellulose (CMC) to modify viscosity at Hcts of 20% and 10% compared to saline-diluted controls. Finally, TEG tracings and whole blood viscosity of naturally anemic dogs were compared immediately before and after red blood cell transfusion. These three experiments demonstrate that increasing the whole blood viscosity of a sample does make TEG tracings appear less hypercoagulable than anemic saline controls, independent of Hct. However, this effect appears to be relatively small, and the Hct has additional effects shifting the TEG tracing towards decreased hypercoagulability, independent of viscosity. The influence of the agent used to alter viscosity demonstrates that ALG may have additional properties that alter coagulation that have not been previously reported. To rule out an artifact of calcium binding, we demonstrate that the effect of CMC-altered viscosity on TEG tracings is preserved even with the addition of extra calcium. Finally, increasing Hct with RBC transfusion in clinically anemic dogs correlates with mildly decreased MA and G TEG values and increased whole blood viscosity. However, these alterations towards decreased hypercoagulability are relatively small compared to the global coagulation status of the animal. Overall, this data indicates that whole blood viscosity does have a small impact on TEG tracings independent of Hct, the effect of RBC mass on TEG tracings is greater than what can be explained by the impact of viscosity alone, and that these changes are relatively small in dogs with clinically significant anemia requiring red blood cell transfusion.
Edward Cooper, Dr. (Advisor)
147 p.
Health Sciences; Medicine; Veterinary Services
Canine; hematocrit; thromboelastography; TEG; anemia; transfusion; alginate; carboxymethylcellulose; viscosity; red blood cell

Recommended Citations

Citations

  • Brooks, A. C. (2014). Effect of whole blood viscosity and red cell mass on canine thromboelastographic tracings [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397244092

    APA Style (7th edition)

  • Brooks, Aimee. Effect of whole blood viscosity and red cell mass on canine thromboelastographic tracings. 2014. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1397244092.

    MLA Style (8th edition)

  • Brooks, Aimee. "Effect of whole blood viscosity and red cell mass on canine thromboelastographic tracings." Master's thesis, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397244092

    Chicago Manual of Style (17th edition)

osu1397244092
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This open access ETD is published by The Ohio State University and OhioLINK.