UC San Diego

Blood transfusions are life-saving procedures designed to provide hemorrhaging patients with the ability to transport oxygen throughout their body by administering blood products. However, resources for these procedures, namely blood donations, are steadily declining in the United States, raising concerns around blood availability during times of emergency or natural disaster. To prevent potential blood shortages, a variety of blood products, including red cell substitutes and plasma expanders, have been developed. Prior to clinical use of these products, their influence in the function of blood must be studied. One important consideration is their impact on the hemostatic state of a patient including prevalence of clotting and coagulation mechanisms impacted. The purpose of this work is to evaluate coagulation changes of four blood replacement products using existing tests and a newly proposed method. Rats were subjected to exchange-infusion of 20% of their blood volume, and a standard panel of clinical assays was performed to determine the impact of 5% HSA, Hextend®, PolyHSA, and PolyHb on coagulation. Results indicate that polymerized bovine hemoglobin supports hemostasis when exposed to collagen, suggesting promising applications for hemorrhaging trauma patients with extreme quantities of exposed collagen. A secondary study tested a different coagulation measurement technique that mimics blood flow in the microvasculature called a U-Thromboelastometer (UTEM), based on the concept of a U-manometer. Results of this study provide proof of concept of this method as it detected variance between red cell substitutes and plasma expanders in the mechanical properties of clots under physiological shear conditions.