Percutaneous delivery of self-propelling hemostatic powder for managing non-compressible abdominal hemorrhage: a proof-of-concept study in swine

Coagulopathy-independent injectable catechol-functionalized chitosan shape-memory material to treat non-compressible hemorrhage

Uncontrolled non-compressible hemorrhage, which is often accompanied by coagulopathy, is a major cause of mortality following traumatic injuries in civilian and military populations. In this study, coagulopathy-independent injectable catechol-modified chitosan (CS-HCA) hemostatic materials featuring rapid shape recovery were fabricated by combining controlled sodium tripolyphosphate-crosslinking with hydrocaffeic acid (HCA) grafting. CS-HCA exhibited robust mechanical strength and rapid blood-triggered shape recovery. Furthermore, CS-HCA demonstrated superior blood-clotting ability, enhanced blood cell adhesion and activation, and greater protein adsorption than commercial hemostatic gauze and Celox. CS-HCA showed enhanced procoagulant and hemostatic capacities in a lethal liver-perforation wound model in rabbits, particularly in heparinized rabbits. CS-HCA is suitable for mass manufacturing and shows promise as a clinically translatable hemostat.

Incidence of Intra-abdominal Adhesions Following Intraperitoneal Injection of Hemostatic Products in Rabbits

INTRODUCTION

Definitive management of non-compressible intra-abdominal hemorrhage (NCIAH) currently requires a surgeon and operating room capable of performing damage control surgery. In a wartime scenario or a geographically remote environment, these may not be readily available. In this study, we sought to test the safety of 2 emerging injectable hemostatic agents (CounterFlow and Fast Onset Abdominal Management, or FOAM, poloxamer component) versus normal saline control over a prolonged monitoring duration following administration by a non-surgical provider.

MATERIALS AND METHODS

The Institutional Animal Care and Use Committee approved all research conducted in this study. We randomized male New Zealand white rabbits into 2 monitoring cohorts of 24 hours and 2 weeks. Each cohort contained 3 treatment groups (n = 4 rabbits/group): CounterFlow, the testable poloxamer component of FOAM, and normal saline control. We injected each treatment intraperitoneally in the left lower abdominal quadrant. Doses were 15 mL/kg for CounterFlow, 6.3 mL/kg for the poloxamer component of FOAM, and 15 mL/kg for normal saline. We conducted all injections under isoflurane anesthesia monitored by trained veterinary staff. Animals were euthanized at each cohort end point, and a veterinary pathologist blinded to treatment type performed necropsy. The primary outcome was incidence of intra-abdominal adhesions at necropsy. Quantitatively, adhesions when present were graded by the veterinary pathologist on a 1 to 4 scale, where "1" represented adhesions involving from 1 to 25% of the examined abdomen, "2" represented from 26 to 50%, "3" represented from 51 to 75%, and "4" represented from 76 to 100%. Qualitatively, adhesions present were graded by degree ("1" = minimal, "2" = mild, "3" = moderate, and "4" = severe) and chronicity ("1" = acute, "2" = subacute, and "3" = chronic). We also drew d-dimer blood values and measured body weights for each animal. Statistical analysis included either repeated measures 2-way ANOVA or a mixed-effects model (in the case of missing data) with Geisser-Greenhouse correction. We adjusted multiple comparisons using Tukey statistical hypothesis tests.

RESULTS

In the 2-week cohort, 3 CounterFlow animals showed adhesions judged to be "1" quantitatively. Qualitatively, 2 of these were assessed as "1" for degree of adhesions and the other demonstrated a "2." On the chronicity of adhesions scale, 1 animal demonstrated a "2" and 2 demonstrated a "3." No animals in other groups (FOAM and control) demonstrated adhesions. CounterFlow-treated animals showed a statistically significant rise in d-dimer values in the 24-hour cohort only. In the 2-week cohort, CounterFlow-treated animals showed a decrease in body weight at 24 hours after injection but returned to their baseline (normal) body weights at 7 days.

CONCLUSIONS

Findings from this study demonstrate that the tested ingredients of FOAM poloxamer component are safe for intraperitoneal injection and hold potential for further study directed toward prehospital non-compressible intra-abdominal hemorrhage management by non-surgical providers. Although CounterFlow produced abdominal adhesions in 3 of 4 rabbits in the 2-week cohort, these were determined to be "minimal" or "mild" in degree.

Torso hemorrhage: noncompressible? never say never

Since limb bleeding has been well managed by extremity tourniquets, the management of exsanguinating torso hemorrhage (TH) has become a hot issue both in military and civilian medicine. Conventional hemostatic techniques are ineffective for managing traumatic bleeding of organs and vessels within the torso due to the anatomical features. The designation of noncompressible torso hemorrhage (NCTH) marks a significant step in investigating the injury mechanisms and developing effective methods for bleeding control. Special tourniquets such as abdominal aortic and junctional tourniquet and SAM junctional tourniquet designed for NCTH have been approved by FDA for clinical use. Combat ready clamp and junctional emergency treatment tool also exhibit potential for external NCTH control. In addition, resuscitative endovascular balloon occlusion of the aorta (REBOA) further provides an endovascular solution to alleviate the challenges of NCTH treatment. Notably, NCTH cognitive surveys have revealed that medical staff have deficiencies in understanding relevant concepts and treatment abilities. The stereotypical interpretation of NCTH naming, particularly the term noncompressible, is the root cause of this issue. This review discusses the dynamic relationship between TH and NCTH by tracing the development of external NCTH control techniques. The authors propose to further subdivide the existing NCTH into compressible torso hemorrhage and NCTH' (noncompressible but REBOA controllable) based on whether hemostasis is available via external compression. Finally, due to the irreplaceability of special tourniquets during the prehospital stage, the authors emphasize the importance of a package program to improve the efficacy and safety of external NCTH control. This program includes the promotion of tourniquet redesign and hemostatic strategies, personnel reeducation, and complications prevention.

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.

The Use of Large Animal Models in Trauma and Bleeding Studies

BACKGROUND

 Major trauma often results in significant bleeding and coagulopathy, posing a substantial clinical burden. To understand the underlying pathophysiology and to refine clinical strategies to overcome coagulopathy, preclinical large animal models are often used. This review scrutinizes the clinical relevance of large animal models in hemostasis research, emphasizing challenges in translating findings into clinical therapies.

METHODS

 We conducted a thorough search of PubMed and EMBASE databases from January 1, 2010, to December 31, 2022. We used specific keywords and inclusion/exclusion criteria centered on large animal models.

RESULTS

 Our review analyzed 84 pertinent articles, including four animal species: pigs, sheep, dogs, and nonhuman primates (NHPs). Eighty-five percent of the studies predominantly utilized porcine models. Meanwhile, sheep and dogs were less represented, making up only 2.5% of the total studies. Models with NHP were 10%. The most frequently used trauma models involved a combination of liver injury and femur fractures (eight studies), arterial hemorrhage (seven studies), and a combination of hemodilution and liver injury (seven studies). A wide array of coagulation parameters were employed to assess the efficacy of interventions in hemostasis and bleeding control.

CONCLUSIONS

 Recognizing the diverse strengths and weaknesses of large animal models is critical for trauma and hemorrhage research. Each model is unique and should be chosen based on how well it aligns with the specific scientific objectives of the study. By strategically considering each model's advantages and limitations, we can enhance our understanding of trauma and hemorrhage pathophysiology and further advance the development of effective treatments.

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.

Emerging hemostatic materials for non-compressible hemorrhage control

Non-compressible hemorrhage control is a big challenge in both civilian life and the battlefield, causing a majority of deaths among all traumatic injury mortalities. Unexpected non-compressible bleeding not only happens in pre-hospital situations but also leads to a high risk of death during surgical processes throughout in-hospital treatment. Hemostatic materials for pre-hospital treatment or surgical procedures for non-compressible hemorrhage control have drawn more and more attention in recent years and several commercialized products have been developed. However, these products have all shown non-negligible limitations and researchers are focusing on developing more effective hemostatic materials for non-compressible hemorrhage control. Different hemostatic strategies (physical, chemical and biological) have been proposed and different forms (sponges/foams, sealants/adhesives, microparticles/powders and platelet mimics) of hemostatic materials have been developed based on these strategies. A summary of the requirements, state-of-the-art studies and commercial products of non-compressible hemorrhage-control materials is provided in this review with particular attention on the advantages and limitations of their emerging forms, to give a clear understanding of the progress that has been made in this area and the promising directions for future generations.

Percutaneous delivery of self-propelling thrombin-containing powder increases survival from non-compressible truncal hemorrhage in a swine model of coagulopathy and hypothermia

BACKGROUND

Non-compressible truncal hemorrhage (NCTH) remains a leading cause of preventable death on the battlefield. Definitively managing severe NCTH requires surgery within the first hour after injury, which is difficult when evacuating casualties from remote and austere environments. During delays to surgery, hemostatic interventions that are performed prehospital can prevent coagulopathy and hemorrhagic shock and increase the likelihood that casualties survive to receive definitive care. We previously reported that a self-propelling thrombin-containing powder (SPTP) can be delivered percutaneously into the abdomen as a minimally invasive intervention and can self-disperse through pooled blood to deliver the hemostatic agents thrombin and tranexamic acid (TXA) locally to noncompressible intracavitary wounds. We hypothesized that in swine with massive NCTH, dilutional coagulopathy and hypothermia, delivering SPTP could extend survival times.

METHODS

Ten swine (n = 5 per group) underwent NCTH from a Grade V liver injury following a midline laparotomy. The laparotomy was closed with sutures afterwards, creating a hemoperitoneum, and animals were managed with crystalloid fluid resuscitation, or crystalloid resuscitation and SPTP. SPTP was delivered into the closed abdomen using a CO2-powered spray device and a catheter placed into the hemoperitoneum, entering through the upper right quadrant using the Seldinger technique. Survival to one and three hours was recorded. In an additional animal, hemorrhage was created laparoscopically and SPTP was imaged in-situ within the abdomen to visually track dispersion of the particles.

RESULTS

SPTP dispersed as far as 35 +/- 5.0 cm within the abdomen. SPTP increased survival to one and three hours (Kaplan-Meier p = 0.007 for both). The median survival time was 61 minutes with SPTP and 31 minutes without (p = 0.016).

CONCLUSION

SPTP effectively disperses medications throughout a hemoperitoneum and increases survival in a model of NCTH. SPTP is a promising strategy for nonsurgical management of NCTH, warranting further testing of its safety and efficacy.

LEVEL OF EVIDENCE

Basic Science, N/A.

Hemostatic biomaterials to halt non-compressible hemorrhage

Non-compressible hemorrhage is an unmet clinical challenge, which occurs in inaccessible sites in the body where compression cannot be applied to stop bleeding. Current treatments reliant on blood transfusion are...