Ruggedized Self-Propelling Hemostatic Gauze Delivers Low Dose of Thrombin and Systemic Tranexamic Acid and Achieves High Survival in Swine With Junctional Hemorrhage

INTRODUCTION

Hemorrhage is responsible for 91% of preventable prehospital deaths in combat. Bleeding from anatomic junctions such as the groin, neck, and axillae make up 19% of these deaths, and reports estimate that effective control of junctional hemorrhage could have prevented 5% of fatalities in Afghanistan. Hemostatic dressings are effective but are time-consuming to apply and are limited when proper packing and manual pressure are not feasible, such as during care under fire. CounterFlow-Gauze is a hemostatic dressing that is effective without compression and delivers thrombin and tranexamic acid into wounds. Here, an advanced prototype of CounterFlow-Gauze, containing a range of low thrombin doses, was tested in a lethal swine model of junctional hemorrhage. Outcomes were compared with those of Combat Gauze, the current dressing recommended by Tactical Combat Casualty Care.

MATERIALS AND METHODS

CounterFlow-Gauze containing thrombin doses of 0, 20, 200, and 500 IU was prepared. Swine received femoral arteriotomies, and CounterFlow-Gauze was packed into wounds without additional manual compression. In a separate study using a similar model of junctional hemorrhage without additional compression, CounterFlow-Gauze containing 500 IU thrombin was tested and compared with Combat Gauze. In both studies, the primary outcomes were survival to 3 h and volume of blood loss.

RESULTS

CounterFlow-Gauze with 200 and 500 IU had the highest 3-h survival, achieving 70 and 75% survival, respectively. CounterFlow-Gauze resulted in mean peak plasma tranexamic acid concentrations of 9.6 ± 1.0 µg/mL (mean ± SEM) within 3 h. In a separate study with smaller injury, CounterFlow-Gauze with 500 IU achieved 100% survival to 3 h compared with 92% in Combat Gauze animals.

CONCLUSIONS

An advanced preclinical prototype of CounterFlow-Gauze formulated with a minimized thrombin dose is highly effective at managing junctional hemorrhage without compression. These results demonstrate that CounterFlow-Gauze could be developed into a feasible alternative to Combat Gauze for hemorrhage control on the battlefield.

Self-propelling thrombin powder enables hemostasis with no observable recurrent bleeding or thrombosis over 3 days in a porcine model of upper GI bleeding

BACKGROUND AND AIMS

Hemostatic powders used to manage upper GI bleeding continue to exhibit high recurrent bleeding rates. Previously, self-propelling thrombin powder (SPTP) sprayed endoscopically managed severe Forrest class 1A bleeding. Here, we evaluate SPTP in a 3-day recovery model of diffuse ulcerated bleeding.

METHODS

Five anesthetized pigs underwent an endoscopic mucosal snare resection to trigger diffuse ulcer bleeding and were treated with SPTP. The time to hemostasis and the amount of powder delivered were measured. Pigs were recovered and monitored.

RESULTS

Five pigs achieved hemostasis in 4.5 ± 1.2 minutes At 3 days after the procedure, the pigs were rescoped and showed no recurrent bleeding. Measured blood parameters were not significantly different from baseline. There were no signs of foreign bodies or thromboembolism during gross necropsy and histopathology of key organs.

CONCLUSIONS

SPTP is a promising novel material that stopped diffuse ulcer bleeding in 5 pigs without recurrent bleeding or adverse local or systemic events.

Efficacy and safety of CounterFlow in animal models of hemorrhage

LAY SUMMARY

The efficacy of current hemostatic technologies is limited by several factors. Outward blood flow washes hemostatic drugs away from the wound, and hemostatic drugs often require focus, training, and time to use correctly, are highly specific to one type of injury, or pose severe safety risks. CounterFlow is a novel product that could potentially save military and civilian lives by stopping heavy bleeding from a variety of organs and other bodily locations that current technology cannot easily treat. Upon contact with blood, CounterFlow releases bursts of gas to safely self-propel bio-degradable clot-forming and clot-stabilizing drugs against blood flow, delivering them to the source of bleeding. This unique mechanism allows CounterFlow to be applied quickly to a wide assortment of wounds and to act effectively with little management after application. CounterFlow was tested in multiple animal models representing common and deadly bleeding scenarios, including internal bleeding, care under fire without compression, and surgical bleeding, and it was found to outperform current care options by stopping bleeds faster and increasing survival times. CounterFlow is also safe to use and biocompatible. This narrative review summarizes studies testing the effectiveness and safety of CounterFlow, discusses useful applications, and describes future plans for the product.

Videoconferencing for Large Animal Trauma Experiments During COVID-19: A Cross-Continent Experience

INTRODUCTION

COVID-19 shutdowns in many research facilities across North America impacted preclinical trauma-related research and development. Shutdown limited the speed and resources available for large animal experiments necessary for advancing medical devices and technologies. However, the pandemic led to the rapid adoption and expansion of videoconferencing in social circles, workplaces, and primary care health settings. Here, we describe the use of simple videoconferencing equipment to plan and carry out 3 total weeks of large animal experiments with a large, cross-continent, interdisciplinary team testing a novel technology in swine models of noncompressible intraabdominal hemorrhage and junctional hemorrhage.

MATERIALS AND METHODS

Animal experiments using swine were scheduled over 3 weeks in February and March 2021 to take place in Toronto, Canada. All relevant animal protocols and COVID-19 site-specific risk assessments were completed and approved by the responsible institutional committees. Experiments were conducted by connecting 12 total research personnel from 3 sites by a simple video conferencing setup which included low-cost, high-definition webcams and standard smartphones streaming to Zoom.

RESULTS

Video conferencing allowed for 3 weeks of trauma experiments to take place at the height of Toronto's third peak of COVID-19 cases. Up to 3 experiments were completed for models requiring 6 hours of monitoring, and up to 5 experiments were completed for models requiring 3 hours of monitoring. The large amount of digital data collected during these experiments was rapidly shared with our network of collaborators, who analyzed results and interpreted findings in real time.

CONCLUSIONS

The system described in this paper has the potential to reduce costs of trauma animal model development and allow for rapid testing and implementation of life-saving devices in settings with limited onsite personnel as experienced during the COVID-19 pandemic.

Emerging gene therapies for enhancing the hemostatic potential of platelets

Platelet transfusions are an integral component of balanced hemostatic resuscitation protocols used to manage severe hemorrhage following trauma. Enhancing the hemostatic potential of platelets could lead to further increases in the efficacy of transfusions, particularly for non-compressible torso hemorrhage or severe hemorrhage with coagulopathy, by decreasing blood loss and improving overall patient outcomes. Advances in gene therapies, including RNA therapies, are leading to new strategies to enhance platelets for better control of hemorrhage. This review will highlight three approaches for creating modified platelets using gene therapies: (i) direct transfection of transfusable platelets ex vivo, (ii) in vitro production of engineered platelets from platelet-precursor cells, and (iii) modifying the bone marrow for in vivo production of modified platelets. In summary, modifying platelets to enhance their hemostatic potential is an exciting new frontier in transfusion medicine, but more preclinical development as well as studies testing the safety and efficacy of these agents are needed.