Use of a modified chitosan dressing in a hypothermic coagulopathic grade V liver injury model

In vitro analysis of tantalum-containing mesoporous bioactive glass fibres for haemostasis

Haemorrhage is the leading cause of battlefield deaths and second most common cause for civilian mortality worldwide. Biomaterials-based haemostatic agents are used to aid in bleeding stoppage; mesoporous bioactive glasses (MBGs) are candidates for haemostasis. Previously made Tantalum-containing MBG (Ta-MBG) powders' compositions were fabricated as electrospun fibres for haemostatic applications in the present study. The fibres were fabricated to address the challenges associated with the powder form: difficult to compress without gauze, getting washed away in profuse bleeding, generating dust in the surgical environment, and forming thick callus-difficult to remove for surgeons and painful for patients. Ta-MBGs were based on (80-x)SiO2-15CaO-5P2O5-xTa2O5 mol% compositions with x = 0 (0Ta), 0.5 (0.5Ta), 1 (1Ta), and 5 (5Ta) mol%. The present study details the fibres' in vitro analyses, elucidating their cytotoxic effects, and haemostatic capabilities and relating these observations to fibre chemistry and previously fabricated powders of the same glasses. As expected, when Ta addition is increased at the expense of silica, a new FTIR peak (non-bridging oxygen-silicon, Si-NBO) develops and Si-O-Si peaks become wider. Compared to 0Ta and 1Ta fibres, 0.5Ta show Si-O peaks with reduced intensity. The fibres had a weaker intensity of Si-NBO peaks and release fewer ions than powders. A reduced ion profile provides fibres with a stable matrix for clot formation. The ion release profile for 1Ta and 5Ta fibres was significantly lower than 0Ta and 0.5Ta fibres. Ta-MBGs were not found to be cytotoxic to primary rat fibroblasts using a methyl thiazolyl tetrazolium (MTT) assay. Furthermore, a modified activated partial thromboplastin time assay analysing the fibrin absorbance showed that the absorption increases from physiological clotting < 0Ta < 0.5Ta < 5Ta < commercial haemostat, Surgical SNoWTM, Ethicon, USA < 1Ta. Higher absorption signifies a stronger clot. It is concluded that Ta-MBG fibres can provide stable matrix for clot formation and 1Ta can potentially enhance clotting best among other Ta-MBGs.

The effectiveness of portable ultrasound-guided resuscitative endovascular balloon occlusion of the aorta for stopping iliac artery hemorrhage during first aid pre-hospital: a randomized control animal trial

PURPOSE

This study aimed at to comparing the effectiveness of portable ultrasound guided REBOA vs. traditional manual extracorporeal compression in stopping iliac artery hemostasis.

METHODS

Twelve swine were included in this study (treatment group vs. control group, 6:6). A biopsy device was used to create an iliac artery rupture and hemorrhage in each swine. After 30 s of bleeding, the treatment group received REBOA under the guidance of ultrasound, whereas the control group received traditional manual extracorporeal compression. General physiological conditions were recorded at 0 s (baseline, T1), 30 s (initiation of therapies to stop bleeding, T2), 10 min (T3) and 30 min (T4) after bleeding. Intraperitoneal and retroperitoneal hemorrhage and specimens of iliac artery were collected after all swine were euthanized.

RESULTS

One swine was excluded because of accidental death not related to the experiment; thus, 11 swine were analyzed in this study. The general physiological characteristics of the two groups showed no difference at T1. Hemorrhagic shock occurred in both groups. After the hemostatic procedure was performed, systolic pressure, diastolic pressure and heart rate first increased significantly between T2 and T3, and then became stable between T3 and T4; these indicators in the control group deteriorated over time. The total blood loss in the treatment group (1245.23 ± 190.07 g) was much significantly less than that in the control group (2605.63 ± 291.67 g) with p < 0.001.

CONCLUSIONS

Performing REBOA under the guidance of portable ultrasound is an effective way to stop bleeding. It suggests a potential alternative method for iliac artery hemostasis in the pre-hospital setting.

Porcine liver injury model to assess tantalum-containing bioactive glass powders for hemostasis

This study evaluates compositions of tantalum-containing mesoporous bioactive glass (Ta-MBG) powders using a porcine fatal liver injury model. The powders based on (80-x)SiO₂-15CaO-5P₂O₅-xTa₂O₅ compositions with x = 0 (0Ta/Ta-free), 1 (1Ta), and 5 (5Ta) mol% were made using a sol-gel process. A class IV hemorrhage condition was simulated on the animals; hemodynamic data and biochemical analysis confirmed the life-threatening condition. Ta-MBGs were able to stop the bleeding within 10 min of their application while the bleeds in the absence of any intervention or in the presence of a commercial agent, Arista^TM (Bard Davol Inc., Rhode Island, USA) continued for up to 45 min. Scanning electron microscopy (SEM) imaging of the blood clots showed that the presence of Ta-MBGs did not affect clot morphology. Rather, the connections seen between fibrin fibers of the blood clot and Ta-MBG powders point towards the powders' surfaces embracing fibrin. Histopathological analysis of the liver tissue showed 5Ta as the only composition reducing parenchymal hemorrhage and necrosis extent of the tissue after their application. Additionally, 5Ta was also able to form an adherent clot in worst-case scenario bleeding where no adherent clot was seen before the powder was applied. In vivo results from the present study agree with in vitro results of the previous study that 5Ta was the best Ta-MBG composition for hemostatic purposes. Graphical abstract.

Dual inhibition of factor XIIa and factor XIa as a therapeutic approach for safe thromboprotection

Clinical practice shows that a critical unmet need in the field of medical device-associated thrombosis prevention is the availability of an anticoagulant therapy without hemorrhagic risk. In the quest for new drugs that are at least as effective as those currently available, while avoiding bleeding complications, molecules that target nearly every step of the coagulation pathway have been developed. Among these molecules, inhibitors of factor XII (FXII) or factor XI (FXI) are promising alternatives as deficiencies in these factors protect against thrombosis without causing spontaneous hemorrhage, as revealed by epidemiological and preclinical data. Ixodes ricinus-contact phase inhibitor (Ir-CPI), a new anticoagulant candidate with an innovative mechanism of action could be this ideal anticoagulant agent for safe prevention from clotting on medical devices. This protein, which selectively binds to FXIIa, FXIa, and plasma kallikrein and inhibits the reciprocal activation of FXII, prekallikrein, and FXI in human plasma, was shown to prevent thrombosis in an ovine cardiopulmonary bypass system associated with cardiac surgeries. Furthermore, as opposed to unfractionated heparin, Ir-CPI appears to be devoid of bleeding risk. This review outlines the rationale for targeting upstream coagulation factors in order to prevent medical device-associated thrombosis; examines the novel approaches under development; and focuses on Ir-CPI, which shows promising properties in the field of thrombosis prevention.

A glimpse on the function of chitosan as a dental hemostatic agent

Managing a bleeding patient can be a challenge during dental surgery. Profuse hemorrhage due to platelet defects, coagulation disorders, vascular anomalies, medication-induced patients, as well as inherited bleeding ailments result in soft tissue hematoma, septic shock, compromised airway, and in some severe cases, death could occur. A vast array of surgical hemostatic agents are available to stop bleeding, including chitosan-based hemostatic agents. Chitosan has an advantage over other topical hemostatic materials for its ability to promote shorter bleeding times and assist in healing. Massive behind-the-scene research and development efforts are ongoing to increase the performance of chitosan as a hemostatic agent. Numerous studies on chitosan use in dental hemostasis have registered it as being safe, biodegradable, biocompatible, promoting healing, antimicrobial and bioactive. This article reviews the application of chitosan in managing hemostasis in dental patients.

A review on recent advances in chitosan based composite for hemostatic dressings

High mortality rate in potentially survivable casualties due to severe hemorrhage is a major challenge in today's battlefield because technological advancements have revolutionized the combat tactics and complicated the type and severity associated with wound grades. Quality of pre-hospital care prior to patient evacuation is crucial in determining the survival rate in injured patients. To deal with this challenge, considerable improvements in the hemostatic dressings have been introduced and pre-hospital care has been upgraded in many tactical combat casually care guidelines. Combat Gauze has been widely used bandage which is now been replaced by different chitosan based hemostatic dressings. It not only exhibits anti-bacterial activity but also induces hemostasis via direct interaction with erythrocytes and platelets. Its hemostasis mechanism is not dependent on host coagulation pathway which makes it an ideal dressing to stop bleeding in coagulopathic patients. Different generations of chitosan bandages have been developed to overcome the limitations of previous ones. This review provides performance analysis of chitosan bandage generations and discusses the progress made in its fabrication methods during the recent years.

Relevance of induced and accidental hypothermia after trauma-haemorrhage-what do we know from experimental models in pigs?

Recent experimental research has either focused on the role of accidental hypothermia as part of the lethal triad after trauma or tried to elucidate the effects of therapeutically induced hypothermia on the posttraumatic course. Induced hypothermia seems to reduce the mortality in experimental models of trauma-haemorrhage. As potential mechanisms, a decrease of cellular metabolism, beneficial effects on haemodynamic function and an attenuation of the inflammatory response have been described. However, negative side effects of hypothermia have to be considered, such as impairment of the coagulatory function and immunosuppressive effects. Furthermore, the optimal strategy for the induction of hypothermia (magnitude, duration, timing, cooling rate, etc.) and subsequent rewarming remains unclear. Nevertheless, this piece of information is essential before considering hypothermia as a treatment strategy for severely injured patients. This review aims to elaborate the differences between accidental and induced hypothermia and to summarize the current knowledge of the potential therapeutic use of induced hypothermia suggested in porcine models of trauma-haemorrhage.

Combined hemorrhage/trauma models in pigs-current state and future perspectives

The majority of injury combinations in multiply injured patients entail the chest, abdomen, and extremities. Numerous pig models focus on the investigation of posttraumatic pathophysiology, organ performance monitoring and on potential treatment options. Depending on the experimental question, previous authors have included isolated insults (controlled or uncontrolled hemorrhage, chest trauma) or a combination of these injuries (hemorrhage with abdominal trauma, chest trauma, traumatic brain injury, and/or long-bone fractures). Combined trauma models in pigs can provide a high level of clinical relevance, when they are properly designed and mimicking the clinical situation. Most of these models focus on the first hours after trauma, to assess the acute sequel of traumatic hemorrhage. However, hemorrhagic shock and the associated mass transfusion are also major causes for organ failure and mortality in the later clinical course. Thus, most models lack information on the pathomechanisms during the late posttraumatic phase. Studying new therapies only during the early phase is also not reflective of the clinical situation. Therefore, a longer observation period is required to study the effects of therapeutic approaches during intensive care treatment when using animal models. These long-term studies of combined trauma models will allow the development of valuable therapeutic approaches relevant for the later posttraumatic course. This review summarizes the existing porcine models and outlines the need for long-term models to provide real effective novel therapeutics for multiply injured patients to improve organ function and clinical outcome.

A self-controlled comparative clinical trial to explore the effectiveness of three topical hemostatic agents for stopping severe epistaxis in pediatrics with inherited coagulopathies

OBJECTIVE

The aim of this study was to assess the effectiveness of localized treatments to persistently stop epistaxis in patients with inherited bleeding disorders.

METHODS

In a self-controlled comparative clinical trial, to offer the best solution to stop epistaxis at home (within 10 minutes), patients with inherited bleeding disorders were treated using three different topical hemostatic agents, including Tranexamic acid impregnated tampon, EpiCell tampon prepared from oxidized regenerated cellulose pad, and ChitoHem tampon (reinforced with chitosan). The results of using these different products on three groups of randomly selected patients were ultimately compared using the χ(2) and Fisher's exact test statistics.

RESULTS

A total of 31 patients, 5 females and 26 males with a mean age of 5.6 years, were included in the study. Twenty-three patients had Glanzmann disease, four had von-Willebrand disease, two had Bernard soulier syndrome, two had activated factor VII deficiency, and one patient had impaired secretion of adenosine deaminase. The study exhibited that statistically there was no significant difference between EpiCell tampon and Tranexamic acid impregnated tampon treatments with respect to the hemostasis duration. However, ChitoHem tampon was more efficient than Tranexamic acid impregnated tampon (P value <0.001) and EpiCell tampon (P value < 0.05).

CONCLUSION

ChitoHem tampon, the chitosan-reinforced product, was the best therapy solution to stop epistaxis. We recommend further research on the use of other hemostatic agents for localized bleeding in patients with inherited bleeding disorders.

In vivo evaluation of the chitosan-based haemostatic agent Omni-stat® in porcine liver resection and in liver injury

BACKGROUND

Omni-stat®, a polysaccharide made by de-acetylation of chitin, is currently in use as a battlefield topical haemostat. This experimental study undertakes the first evaluation of Omni-stat in an in vivo porcine hepatectomy and liver trauma model.

METHODS

A model of sequential liver resection was employed: following liver resection, further resections were undertaken in the same animal provided that there was cessation of bleeding from the earlier resection and that haemodynamic stability was maintained. An additional liver trauma injury was undertaken after completion of all resections. Data were collected on heart rate, blood pressure, haematocrit, resection volumes, blood loss and the efficacy of Omni-stat in haemostasis.

RESULTS

Eight minor resections and 12 major resections were undertaken. Topical application of Omni-stat to raw post-transection surfaces immediately upon completion of resection achieved complete haemostasis with a single application in 14 of 15 (93%) resections. There was no recurrence of bleeding during the 5-hour protocol. The median time for cessation of bleeding after resection in the Omni-stat group was 3 min (range 3-6). This was not significantly different from time to cessation of bleeding in 5 control resections. There was no difference in blood loss or haemodynamic parameters. Respiratory rate was significantly faster after application of Omni-stat. In 2 liver lacerations, Omni-stat was effective in achieving cessation of haemorrhage.

CONCLUSION

Omni-stat is an effective haemostat in experimental in vivo porcine liver resection and liver trauma. Further evaluation is required to assess its physiological absorption profile in man and its comparative efficacy against commercially established agents.

Intracorporeal use of advanced local hemostatics in a damage control swine model of grade IV liver injury

BACKGROUND

The purpose of this study was to evaluate the efficacy of zeolite- and chitosan-based local hemostatic agents for the control of intracorporeal bleeding in a damage control swine model of grade IV liver injury.

METHODS

Anesthetized pigs (weight, 40 kg) had a controlled 35% total blood volume bleed from the right jugular vein. A laparotomy was performed and the animals were cooled to 35°C. Ringer's lactate was titrated to achieve a three to one blood withdrawal resuscitation. The liver was injured with a standardized 10 cm × 3 cm avulsion. After 2 minutes of uncontrolled hemorrhage, the animals were randomized to application of gauze control (GC, n = 11), Celox (CX, n = 11) (5AM Medical, Newport, OR), or QuikClot ACS (QC, n = 11) (7-Medica, Wallington, CT) and packed in a standardized manner. At 10 minutes, the packs were removed to calculate amount of shed blood. The animals then underwent damage control closure with packing in place. Forty-eight hours after initial damage control packing, the animals were returned to the operating room for pack removal and killing. The need for repacking of the liver was assessed and tissue samples were collected from the liver edge and adjacent small bowel for histopathology.

RESULTS

There was no difference in the amount of uncontrolled bleeding at 2 minutes (GC: 4.0 mL/kg ± 0.4 mL/kg, CX: 3.5 mL/kg ± 0.5 mL/kg, QC: 4.0 mL/kg ± 0.6 mL/kg; one-way analysis of variance: p = 0.715). Compared with GCs, the blood loss at 10 minutes was significantly lower in the CX and QC arms (GC: 8.3 mL/kg ± 0.9 mL/kg, CX: 3.7 mL/kg ± 0.7 mL/kg, QC: 4.6 mL/kg ± 0.8 mL/kg; one-way analysis of variance: p = 0.001). A total of 27.3% of control animals died compared with 18.2% of CX and 0.0% of QC. All GC and QC animals required repacking, compared with one (9.1%) of those in the CX arm. There was no difference between groups in the extent of necrosis.

CONCLUSION

Celox and QuikClot ACS(+) are effective adjuncts to standard intracavitary damage control packing for the control of bleeding. Celox provided durable control allowing packing removal at the time of take-back laparotomy. Further evaluation of their long-term effects is warranted.

Pre-hospital haemostatic dressings: a systematic review

BACKGROUND

Uncontrolled haemorrhage is a leading cause of prehospital death after military and civilian trauma. Exsanguination from extremity wounds causes over half of preven military combat deaths and wounds to the anatomical junctional zones provide a particular challenge for first responders. Commercial products have been developed, which claim to outperform standard gauze bandages in establishing and maintaining non-surgical haemostasis. Since 2004, two advanced haemostatic dressing products, HemCon and QuikClot have been widely deployed in military operations. Newer products have since become available which aim to provide more efficient haemostasis than and thus supersede HemCon and QuikClot.

AIM

To conduct a systematic review of clinical and preclinical evidence to compare the relative efficacy and safety of available haemostatic products, which are of relevance to pre-hospital military and civilian emergency medical providers.

METHOD

An English language literature search was performed, using PubMed and Web of Knowledge Databases, with cross-referencing, focussed product searches and communication with product manufacturers. For studies employing animal models, the injury model was required to produce fatal haemorrhage. Products were categorised by primary mode of action as either factor concentrators,mucoadhesive agents or procoagulant supplementors.

RESULTS

From 60 articles collated, 6 clinical papers and 37 preclinical animal trials were eligible for inclusion in this review. Products have been tested in three different types of haemorrhage model: low pressure, high volume venous bleeding, high pressure arterial bleeding and mixed arterial-venous bleeding. The efficacy of products varies with the model adopted. Criteria for the 'ideal battle field haemostatic dressing' have previously been defined by Pusateri, but no product has yet attained suchstatus. Since 2004, HemCon (a mucoadhesive agent) and QuikClot (a factor concentrator) have been widely deployed by United States and United Kingdom Armed Forces; retrospective clinical data supports their efficacy. However, in some recent animal models of lethal haemorrhage, WoundStat(mucoadhesive), Celox (mucoadhesive) and CombatGauze (procoagulant supplementor) have all outperformed both HemCon and QuikClot products.

CONCLUSION

HemCon and QuikClot have augmented the haemostatic capabilities of the military first aid responder, but newer products demonstrate potential to be more effective and should be considered as replacements for current in service systems. These products could have utility for civilian pre-hospital care.

Chitosan modification and pharmaceutical/biomedical applications

Chitosan has received much attention as a functional biopolymer for diverse applications, especially in pharmaceutics and medicine. Our recent efforts focused on the chemical and biological modification of chitosan in order to increase its solubility in aqueous solutions and absorbability in the in vivo system, thus for a better use of chitosan. This review summarizes chitosan modification and its pharmaceutical/biomedical applications based on our achievements as well as the domestic and overseas developments: (1) enzymatic preparation of low molecular weight chitosans/chitooligosaccharides with their hypocholesterolemic and immuno-modulating effects; (2) the effects of chitin, chitosan and their derivatives on blood hemostasis; and (3) synthesis of a non-toxic ion ligand--D-Glucosaminic acid from oxidation of D-Glucosamine for cancer and diabetes therapy.