UBC Theses and Dissertations
Improving the efficacy of hemostatic agents by increasing their transport into wounds Baylis, James
Uncontrollable hemorrhage remains a leading cause of mortality in many situations, including during surgery and following trauma. Many hemostatic interventions have been developed, but mortality and morbidity remain high because they are ineffective or difficult to use in cases of severe bleeding. Blood flow can rapidly wash away topically applied hemostatic agents and prevents them from reaching leaking vessels and forming robust clots. We hypothesized that increasing the transport of hemostatic agents into wounds could improve their ability to manage bleeding. To test this hypothesis, I developed self-propelling particles that can transport through flowing blood and into wounds. These particles, consisting of calcium carbonate and an organic acid, delivered two hemostatic agents, thrombin and tranexamic acid (TXA), and improved their ability to stop bleeding in mice (Chapter 3). Next, I showed that self-propelling particles loaded with thrombin applied with gauze (PTG) significantly improved survival in a swine model of massive traumatic bleeding without compression, compared to those agents on gauze without propulsion (Chapter 4). This demonstrates that increasing transport of hemostatic agents could increase their utility for managing clinically relevant hemorrhage, such as from battlefield trauma. In two sheep models of surgical hemorrhage, PTG’s ability to stop bleeding was compared to two clinical standard interventions (Chapter 5). In a model of endoscopic surgical bleeding, PTG significantly reduced bleeding time compared to control gauze. In a model of massive open surgical bleeding, PTG achieved hemostasis in more cases than a standard thrombin-containing hemostatic agent. These demonstrate that increased transport of hemostatic agents could enable improved management of surgical bleeding. Finally, formulating TXA with self-propelling particles increased its ability to inhibit fibrinolysis in vitro and reduce bleeding in mice in vivo, demonstrating that these particles could transport a variety of hemostatic agents and increase their efficacy too (Chapter 6). The findings of this thesis suggest that improving the transport of hemostatic agents into wounds, such as by using self-propelling particles, is a promising approach for increasing the efficacy of those agents, and may present an opportunity to reduce mortality, morbidity, and the clinical burden associated with bleeding.
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