Hemostatic Efficacy of a Recombinant Thrombin-Coated Polyglycolic Acid Sheet Coupled With Liquid Fibrinogen, Evaluated in a Canine Model of Pulmonary Arterial Hemorrhage

Thermoresponsive shear-thinning hydrogel (T-STH) hemostats for minimally invasive treatment of external hemorrhages

Hemorrhage is the leading cause of death following battlefield injuries. Although several hemostats are commercially available, they do not meet all the necessary requirements to stop bleeding in combat injuries. Here, we engineer thermoresponsive shear-thinning hydrogels (T-STH) composed of a thermoresponsive polymer, poly(N-isopropyl acrylamide) (p(NIPAM)), and hemostatic silicate nanodisks, LAPONITE®, as minimally invasive injectable hemostatic agents. Our T-STH is a physiologically stable hydrogel that can be easily injected through a syringe and needle and exhibits rapid mechanical recovery. Additionally, it demonstrates temperature-dependent blood coagulation owing to the phase transition of p(NIPAM). It decreases in vitro blood clotting times over 50% at physiological temperatures compared to room temperature. Furthermore, it significantly prevents blood loss in an ex vivo bleeding model at different blood flow rates (1 mL min^-1 and 5 mL min^-1) by forming a wound plug. More importantly, our T-STH is comparable to a commercially available hemostat, Floseal, in terms of blood loss and blood clotting time in an in vivo rat liver bleeding model. Furthermore, once the hemorrhage is stabilized, our T-STH can be easily removed using a cold saline wash without any rebleeding or leaving any residues. Taken together, our T-STH can be used as a first aid hemostat to treat external hemorrhages in emergency situations.

Hemostatic agents for prehospital hemorrhage control: a narrative review

Hemorrhage is the leading cause of preventable death in combat trauma and the secondary cause of death in civilian trauma. A significant number of deaths due to hemorrhage occur before and in the first hour after hospital arrival. A literature search was performed through PubMed, Scopus, and Institute of Scientific Information databases for English language articles using terms relating to hemostatic agents, prehospital, battlefield or combat dressings, and prehospital hemostatic resuscitation, followed by cross-reference searching. Abstracts were screened to determine relevance and whether appropriate further review of the original articles was warranted. Based on these findings, this paper provides a review of a variety of hemostatic agents ranging from clinically approved products for human use to newly developed concepts with great potential for use in prehospital settings. These hemostatic agents can be administered either systemically or locally to stop bleeding through different mechanisms of action. Comparisons of current hemostatic products and further directions for prehospital hemorrhage control are also discussed.

Carbon Monoxide-Releasing Molecule Enhances Coagulation and Decreases Fibrinolysis in Normal Canine Plasma

The dog is an important companion animal and also purpose-bred for research studies. Coagulopathies in dogs are common, although the availability of blood products for therapy is inconsistent throughout the profession. A pro-coagulant therapeutic that is readily available and easily stored would be useful for the treatment of coagulopathies. Tricarbonyldichlororuthenium (II) dimer [Carbon monoxide-releasing molecule-2 (CORM-2)] acts as a prothrombotic agent in plasma by increasing the velocity of clot formation and clot strength, and by decreasing the clot's vulnerability to fibrinolysis. We sought to test CORM-2's effect on coagulation and fibrinolysis in vitro in canine plasma using thromboelastography. Measures of the rate of clot formation and clot strength in plasma without CORM-2 were highly correlated with fibrinogen concentration. We found that CORM-2 significantly enhanced the rate of clot formation and clot strength and significantly reduced the rate of fibrinolysis and the clot lysis time. The per cent change in rate of clot formation and clot strength was not significantly correlated with fibrinogen concentration, indicating that CORM-2's pro-coagulant effect is not dependent on fibrinogen concentration. This study corroborates studies in other species that show that CORM-2 is pro-coagulant in plasma, and lays the groundwork for developing CORM-2 as a therapeutic agent for canine coagulopathies. Future studies will evaluate the effect of CORM-2 on whole blood both in vitro and in vivo.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

Polyglycolic acid sheet with fibrin glue potentiates the effect of a fibrin-based haemostat in cardiac surgery

BACKGROUND

Hemorrhage from the left ventricle can be critical and sutureless repair using a fibrin-based haemostat (TachoComb) is one effective option. When active hemorrhage is not controlled by the haemostat, we have used a polyglycolic acid (PGA) sheet and fibrin glue in addition. Here we investigated whether the PGA sheet and fibrin glue combined with TachoComb had stronger adhesive properties than TachoComb alone in two experimental models.

METHODS

Experiment 1. An airtight circuit that included rabbit skin with holes covered by each type of sealant was gradually pressurized and the burst pressure was recorded automatically (n = 10). Experiment 2. A suture loop was attached to a porcine heart by each sealant, and the peel-off pressure was measured (n = 12).

RESULTS

The PGA sheet and fibrin glue combined with TachoComb showed significantly higher adhesive strength than TachoComb alone in both experiments (p < 0.05).

CONCLUSIONS

Adding a PGA sheet and fibrin glue increased the adhesive strength of TachoComb in two experimental models, suggesting that this method might be effective for achieving haemostasis in difficult clinical situations.

Polyglycolic acid sheet with fibrin glue potentiates the effect of a fibrin-based haemostat in cardiac surgery

Background

Hemorrhage from the left ventricle can be critical and sutureless repair using a fibrin-based haemostat (TachoComb) is one effective option. When active hemorrhage is not controlled by the haemostat, we have used a polyglycolic acid (PGA) sheet and fibrin glue in addition. Here we investigated whether the PGA sheet and fibrin glue combined with TachoComb had stronger adhesive properties than TachoComb alone in two experimental models.

Methods

Experiment 1. An airtight circuit that included rabbit skin with holes covered by each type of sealant was gradually pressurized and the burst pressure was recorded automatically (n = 10). Experiment 2. A suture loop was attached to a porcine heart by each sealant, and the peel-off pressure was measured (n = 12).

Results

The PGA sheet and fibrin glue combined with TachoComb showed significantly higher adhesive strength than TachoComb alone in both experiments (p < 0.05).

Conclusions

Adding a PGA sheet and fibrin glue increased the adhesive strength of TachoComb in two experimental models, suggesting that this method might be effective for achieving haemostasis in difficult clinical situations.

Mesenteric lymphatic ducts ligation decreases the degree of gut-induced lung injury in a portal vein occlusion and reperfusion canine model

BACKGROUND

Whether the mesenteric lymphatic system could serve as a route of transport by which gut-derived inflammatory mediators contribute to the induction of remote organ injuries is uncertain. We therefore made a gut-induced lung injury canine model by portal vein occlusion and reperfusion (PV O/R) and studied the role of mesenteric lymphatic ducts ligation (ML) to gut-induced lung injury with this model.

MATERIAL AND METHODS

Eighteen mongrel dogs were divided into control, PV O/R, and PV O/R + ML groups. Cytokines and endotoxin levels in the portal vein and lymph from thoracic duct in different groups were tested. The permeability, myeloperoxidase activity, and histopathological investigation of intestine and lung were evaluated.

RESULTS

Cytokines and endotoxin levels in the portal vein were significantly increased in experimental groups compared with control group (P < 0.05), and that in the lymph from thoracic duct were significantly increased in PV O/R group compared with control and PV O/R + ML group (P < 0.05). Lung permeability and MPO activity in PV O/R group were significantly higher than those in control and PV O/R + ML group (P < 0.05); intestinal permeability in experimental groups were significantly higher with respect to control group. The lung injury score in PV O/R group was significantly higher than those in control and PV O/R + ML group (P < 0.05) and the intestinal injury scores in experimental groups were significantly higher than control group (P < 0.05).

CONCLUSIONS

The gut-induced lung injury canine model made by PV O/R is successful, and mesenteric lymphatic ducts ligation decreases the degree of gut-induced lung injury in this model.