A safety review of topical bovine thrombin-induced generation of antibodies to bovine proteins

Antifibrinolytic and Adjunct Hemostatic Agents: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic-review informed, modified Delphi consensus regarding antifibrinolytic and adjunct hemostatic agents in neonates and children supported with extracorporeal membrane oxygenation (ECMO) for the Pediatric ECMO Anticoagulation CollaborativE consensus conference.

DATA SOURCES

A structured literature search was performed using PubMed, EMBASE, and Cochrane Library (CENTRAL) databases from January 1988 to May 2021.

STUDY SELECTION

Use of antifibrinolytics (epsilon-aminocaproic acid [EACA] or tranexamic acid), recombinant factor VII activated (rFVIIa), or topical hemostatic agents (THAs).

DATA EXTRACTION

Two authors reviewed all citations independently, with a third independent reviewer resolving conflicts. Eleven references were used for data extraction and informed recommendations. Evidence tables were constructed using a standardized data extraction form.

MEASUREMENTS AND MAIN RESULTS

Risk of bias was assessed using the Quality in Prognosis Studies tool. The evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation system. Forty-eight experts met over 2 years to develop evidence-based recommendations and, when evidence was lacking, expert-based consensus statements for the management of bleeding and thrombotic complications in pediatric ECMO patients. A web-based modified Delphi process was used to build consensus via the Research And Development/University of California Appropriateness Method. Consensus was defined as greater than 80% agreement. One weak recommendation and three consensus statements are presented.

CONCLUSIONS

Evidence supporting recommendations for administration of antifibrinolytics (EACA or tranexamic acid), rFVIIa, and THAs were sparse and inconclusive. Much work remains to determine effective and safe usage strategies.

Comparison between platelet-rich plasma (PRP) and mechanically emulsified fat grafts in management of chronic wounds

BACKGROUND

chronic wounds represent a challenge in treatment, due to diverse pathogenesis, resistance to ordinary treatment complex and lack of direct methods of treatment In this study, the aim is to compare the effect of Platelet -rich plasma (PRP) and mechanically emulsified fat grafts on the outcome of the healing process of chronic wounds.

PATIENTS AND METHODS

In the current study, 30 patients with chronic wounds were divided into two groups (Group I, 15 patients had application of PRP on chronic wounds). Whereas (Group II, 15 patients had application of mechanically emulsified fat on chronic wounds). In both groups assessment of the healing rates and histopathological changes that were determined by observing the parameters of wound healing, including peri-lesional skin quality, observation of the wound size and depth, assessment of the pain indicated by Visual analog scale score.

RESULTS

Patient were followed up for 6 months. Group II showed a better healing rate 64% in comparison to Group I 55%. Wound parameters and pain score were recorded in both groups with no statistically significant difference.

CONCLUSION

Both PRP and mechanically emulsified fat grafts were found to be efficient treatment modalities in management of chronic "non-healing" wounds. But mechanically emulsified fat grafts represent a better treatment method for chronic wounds.

Composition, host responses and clinical applications of bioadhesives

Bioadhesives are medical devices used to join or seal tissues that have been injured or incised. They have been classified into tissue adhesives, sealants, and hemostatic agents. Bioadhesives such as FloSeal®, CoSeal®, BioGlue®, Evicel®, Tisseel®, Progel™ PALS, and TissuGlu® have been commercialized and used in clinical setting. They can be formulated with natural or synthetic components or a combination of both including albumin, glutaraldehyde, chitosan, cyanoacrylate, fibrin and thrombin, gelatin, polyethylene glycol (PEG), along with urethanes. Each formulation has intrinsic properties and has been developed and validated for a specific application. This review article briefs the mechanisms by which bioadhesives forms adhesion to tissues and highlights the correlation between bioadhesives composition and their potential host responses. Furthermore, clinical applications of bioadhesives and their application-driven requirements are outlined.

Dependence of Electric Pulse Mediated Growth Factor Release on the Platelet Rich Plasma Separation Method

Platelet rich plasma (PRP) has been explored for multiple clinical applications, including dentistry, orthopedics, sports medicine, diabetic foot ulcers, and cosmetic treatments. Topical applications of PRP typically use thrombin to induce platelet activation, which is accompanied by growth factor release and clotting of the PRP, prior to treatment. Injectable PRP treatments typically use non-activated PRP under the assumption that collagen at the site of the injury mediates platelet activation to ensure growth factor release in vivo. Ex-vivo electrical stimulation of platelets is emerging as a robust, easy to use, instrument-based PRP activation technique to facilitate growth factor release with or without clotting, while providing tunability of growth factor release, clot mechanical properties (when desired), and serotonin release from the dense granules. This paper briefly reviews the key results of the electrical activation of platelets and demonstrates successful growth factor release by electrical ex-vivo stimulation without clotting for three types of PRP separated from whole blood using available commercial kits: Harvest, EmCyte and Eclipse. While these three types of PRP feature a wide range of platelet and red blood cell content compared to whole blood, we demonstrate that pulsed electric fields enable growth factor release for all these biological matrices generated using whole blood from four human donors. These experiments open opportunities for using electrically stimulated PRP with released growth factors without clotting for injectable platelet treatments in relevant clinical applications.

Advances in the development of hemostatic biomaterials for medical application

BACKGROUND

Medical hemostatic biological materials are necessary for the development of the process of preventing and stopping damaged intravascular bleeding. In the process, some red blood cells and white blood cells are trapped in nets. The resulting plug is called a blood clot. This is often a good step in wound healing, but separation of blood clots from blood vessel walls can cause serious health problems.

MAIN BODY

The advance in the development of hemostatic biomaterials is necessary for biomedical application. Firstly, the historical background of artificial hemostasis has been included and the current research of hemostasis has been included in more detail. Secondly, the current research of hemostasis has been included on the oxidized cellulose-based hemostatic biomaterials such as starch based on composite cross-linking hemostatic networks, hemostatic materials on NHS-esters, hemostatic agent from local materials and biomaterials for hemostatic management. Thirdly, polysaccharide hemostatic materials, bio-inspired adhesive catechol-conjugated chitosan, mesoporous silica and bioactive glasses for improved hemostasis, minimally invasive hemostatic biomaterials and chitosan-base materials for hemostatic application have been included. Fourthly, the biological properties of natural hemostatic agent by plasma technology and the hemostatic agents based on gelatin-microbial transglutaminase mixes have been also included.

CONCLUSION

Current research on hemostasis includes hemostatic biomaterials such as cellulose-based hemostatic starch based on a complex cross-linked hemostatic network. It also includes polysaccharide hemostatic materials, biomimetic adhesive catechol-binding chitosan, mesoporous silica or physiologically active glass for hemostatic improvement, minimally invasive hemostatic chitosan-based materials, and gelatin-microbial transglutaminase-based hemostatic agents. Future studies should focus on modular combination of hemostatic imitation and reinforcement mechanisms of different materials and technologies to find the optimal system to promote and strengthen active platelet or platelet imitation aggregation in bleeding sites. The second optionally increases the production of thrombin and fiber formation at the site. Third, the formed fibrin biopolymer network has strengthened to reduce thrombosis and amplify hemostasis.

Electrical stimulation of whole blood for growth factor release and potential clinical implications

Clinicians have increasingly applied platelet-rich plasma (PRP) for wound healing treatments. Topical treatments commonly require biochemical agents such as bovine thrombin to activate PRP ex vivo for clotting and growth factor release to facilitate healing upon application to the wound of interest. Recent studies have explored electrical stimulation as an alternative to bovine thrombin for PRP activation due to the former's cost, workflow complexity and potentially significant side effects; however, both approaches require separating the PRP from whole blood (WB) prior to activation. Eliminating the separation (typically centrifugation) step would reduce the cost and duration of the clinical procedure, which may be critical in trauma and surgical applications. We hypothesize that electric pulses (EPs) can release growth factors from WB, as they do from PRP, without requiring centrifugation of WB into PRP. A pilot study for two donors demonstrates the potential for EP stimulated growth factor release from WB. This motivates future experiments assessing EP parameter optimization for WB activation and in vivo studies to determine the clinical benefits for topical treatments and, especially, for injections in orthopedic applications that already utilize non-treated/non-activated WB.

DNA-nanorobot-guided thrombin-inducing tumor infarction: raising new potential clinical concerns

DNA-nanorobot-guided thrombin-inducing tumor infarction (DNA NanorobotTh-ITI) is emerging as a powerful therapeutic strategy for treatment of solid cancers. The technology represents a major advance in the application of DNA nanotechnology for anticancer therapy. More importantly, the technology is being translated from preclinical studies to the clinic owing to its promising anticancer effects with fewer toxicities demonstrated in preclinical settings. However, despite these beneficial effects of the technology, it is important to point out that some important potential clinical concerns remain to be addressed. Here, we raise these clinical concerns along with these beneficial effects of the technology. Hopefully, these newly raised potential clinical concerns could drive forward research in this field to expedite its clinical translation.

Successful Outcome of Severe Intra-cerebral Bleeding Associated with Acquired Factor V Inhibition: Utilization of Multiple Therapeutic Agents

Background:

Acquired coagulation factor inhibitors are antibodies that either inhibit activity or increase the clearance of a clotting factor and lead to an increased risk of bleeding. Most of the time, the disorder is attributed to factor VIII inhibition (acquired haemophilia A); however, other coagulation factors could also be implicated.

Case Report:

Herein, we report an interesting case of a patient who underwent coronary artery bypass grafting and received antibiotic treatment after surgery with third generation cephalosporin. A month later, he presented with extreme bleeding diathesis and cerebral haemorrhage. Following a thorough clinical and laboratory investigation, an acquired factor V inhibitor was diagnosed. The patient received treatment with corticosteroids, intravenous immunoglobulins, anti-CD20 monoclonal antibodies (rituximab), cyclophosphamide and recombinant factor VIIa. Finally, despite the poor initial prognosis, the patient managed to achieve a full recovery.

Conclusion:

As there are no clear guidelines on acquired coagulation inhibitor treatment, reports of such cases could offer insight for future therapy choices. The case was unique because the treatment regimen included a combination of multiple therapeutic agents including rituximab.

Modification of Pulsed Electric Field Conditions Results in Distinct Activation Profiles of Platelet-Rich Plasma

Background

Activated autologous platelet-rich plasma (PRP) used in therapeutic wound healing applications is poorly characterized and standardized. Using pulsed electric fields (PEF) to activate platelets may reduce variability and eliminate complications associated with the use of bovine thrombin. We previously reported that exposing PRP to sub-microsecond duration, high electric field (SMHEF) pulses generates a greater number of platelet-derived microparticles, increased expression of prothrombotic platelet surfaces, and differential release of growth factors compared to thrombin. Moreover, the platelet releasate produced by SMHEF pulses induced greater cell proliferation than plasma.

Aims

To determine whether sub-microsecond duration, low electric field (SMLEF) bipolar pulses results in differential activation of PRP compared to SMHEF, with respect to profiles of activation markers, growth factor release, and cell proliferation capacity.

Methods

PRP activation by SMLEF bipolar pulses was compared to SMHEF pulses and bovine thrombin. PRP was prepared using the Harvest SmartPreP2 System from acid citrate dextrose anticoagulated healthy donor blood. PEF activation by either SMHEF or SMLEF pulses was performed using a standard electroporation cuvette preloaded with CaCl₂ and a prototype instrument designed to take into account the electrical properties of PRP. Flow cytometry was used to assess platelet surface P-selectin expression, and annexin V binding. Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and platelet factor 4 (PF4), and were measured by ELISA. The ability of supernatants to stimulate proliferation of human epithelial cells in culture was also evaluated. Controls included vehicle-treated, unactivated PRP and PRP with 10 mM CaCl₂ activated with 1 U/mL bovine thrombin.

Results

PRP activated with SMLEF bipolar pulses or thrombin had similar light scatter profiles, consistent with the presence of platelet-derived microparticles, platelets, and platelet aggregates whereas SMHEF pulses primarily resulted in platelet-derived microparticles. Microparticles and platelets in PRP activated with SMLEF bipolar pulses had significantly lower annexin V-positivity than those following SMHEF activation. In contrast, the % P-selectin positivity and surface P-selectin expression (MFI) for platelets and microparticles in SMLEF bipolar pulse activated PRP was significantly higher than that in SMHEF-activated PRP, but not significantly different from that produced by thrombin activation. Higher levels of EGF were observed following either SMLEF bipolar pulses or SMHEF pulses of PRP than after bovine thrombin activation while VEGF, PDGF, and PF4 levels were similar with all three activating conditions. Cell proliferation was significantly increased by releasates of both SMLEF bipolar pulse and SMHEF pulse activated PRP compared to plasma alone.

Conclusions

PEF activation of PRP at bipolar low vs. monopolar high field strength results in differential platelet-derived microparticle production and activation of platelet surface procoagulant markers while inducing similar release of growth factors and similar capacity to induce cell proliferation. Stimulation of PRP with SMLEF bipolar pulses is gentler than SMHEF pulses, resulting in less platelet microparticle generation but with overall activation levels similar to that obtained with thrombin. These results suggest that PEF provides the means to alter, in a controlled fashion, PRP properties thereby enabling evaluation of their effects on wound healing and clinical outcomes.

Platelet-rich plasma stimulated by pulse electric fields: Platelet activation, procoagulant markers, growth factor release and cell proliferation

Therapeutic use of activated platelet-rich plasma (PRP) has been explored for wound healing, hemostasis and antimicrobial wound applications. Pulse electric field (PEF) stimulation may provide more consistent platelet activation and avoid complications associated with the addition of bovine thrombin, the current state of the art ex vivo activator of therapeutic PRP. The aim of this study was to compare the ability of PEF, bovine thrombin and thrombin receptor activating peptide (TRAP) to activate human PRP, release growth factors and induce cell proliferation in vitro. Human PRP was prepared in the Harvest SmartPreP2 System and treated with vehicle, PEF, bovine thrombin, TRAP or Triton X-100. Platelet activation and procoagulant markers and microparticle generation were measured by flow cytometry. Released growth factors were measured by ELISA. The releasates were tested for their ability to stimulate proliferation of human epithelial cells in culture. PEF produced more platelet-derived microparticles, P-selectin-positive particles and procoagulant annexin V-positive particles than bovine thrombin or TRAP. These differences were associated with higher levels of released epidermal growth factor after PEF than after bovine thrombin or TRAP but similar levels of platelet-derived, vascular-endothelial, and basic fibroblast growth factors, and platelet factor 4. Supernatant from PEF-treated platelets significantly increased cell proliferation compared to plasma. In conclusion, PEF treatment of fresh PRP results in generation of microparticles, exposure of prothrombotic platelet surfaces, differential release of growth factors compared to bovine thrombin and TRAP and significant cell proliferation. These results, together with PEF's inherent advantages, suggest that PEF may be a superior alternative to bovine thrombin activation of PRP for therapeutic applications.

Life-threatening large subcutaneous hematoma after minor head trauma: A young female patient who was suspected of having new Ehlers-Danlos syndrome

Life-threatening large subcutaneous hematomas after minor injury are rare clinical states for young people; however these patients may have hidden diseases, which can cause a tendency to bleed. A 31-year-old woman visited our hospital after minor injury. The first computed tomography (CT) scan revealed a small subcutaneous hematoma, but her head bulged and the second CT scan revealed her subcutaneous hematoma had become enlarged. Two surgeries were needed to stop the bleeding and. Though she received intensive care, she died 48 days after onset. The new Ehlers–Danlos syndrome (EDS), known as EDS Kosho type (EDSKT), is a connective tissue disease, in which patients often experience large subcutaneous hematomas. We suspected our patient had EDSKT because her clinical features were compatible with this syndrome. Our findings support the notion that large subcutaneous hematomas in young patients with connective tissue disease can be fatal; a careful follow-up is required.

Nanocomplexation of thrombin with cationic amylose derivative for improved stability and hemostatic efficacy

As a topical hemostatic agent, thrombin has wide application for many surgical treatments. However, native thrombin always suffers from its physical and chemical instabilities. In this work, a nanocomplexation strategy was developed for modifying the stability and hemostatic efficacy of thrombin, in which a water-soluble cationic amylose derivative containing poly(l-lysine) dendrons was prepared by a click reaction and then used to complex thrombin in an aqueous system. For resultant thrombin nanocomplexes, their morphology and particle size distribution were investigated. Their stabilities were studied in terms of activity retention percentages under different storage time, pH values, and illumination time. In addition, their ability to achieve in vitro fibrinogen and blood coagulation were evaluated. Via a rat hepatic hemorrhage model and a rat iliac artery hemorrhage model, these thrombin nanocomplexes were confirmed to have good tissue biocompatibility and in vivo hemostatic effectiveness.

Use of topical bovine thrombin in an anti-coagulated rat model of hepatic injury

The need for surgical hemostasis in patients treated with anticoagulant medications is a concern. This study assessed a bovine-derived topical hemostat (FastAct, FA) using a partial hepatectomy hemorrhage model in anticoagulated rats. Ninety rats were randomly assigned to receive preoperative heparin, warfarin, or nothing (n=30/treatment). Within each treatment group, FA, saline, direct pressure (DP), electrocautery, or nothing (n=6/group) was applied to the hepatectomy site. Eight additional rats were used for assessment of the preoperative anticoagulant regimen. Rats that were not anticoagulated and received FA had faster clot times and less hemorrhage than those receiving DP (P<0.05). In warfarin-pretreated rats, FA resulted in faster coagulation times than saline or DP and less hemorrhage than saline (P<0.05). No differences were detected in heparinized rats. Across all groups, rats receiving FA lost less blood and formed clots more frequently than saline (P<0.05). FA may be useful to treat hemorrhage from hepatic lacerations in anticoagulated patients.

Platelet-rich plasma activation in combination with biphasic osteochondral scaffolds-conditions for maximal growth factor production

PURPOSE

The combination of scaffolds and biological factors may enhance articular cartilage repair. Little is known regarding the activation and subsequent growth factor release of platelet-rich plasma (PRP) in contact with biosynthetic scaffolds. The purpose of this study was i) to identify whether the addition of thrombin was required to activate PRP in the presence of a collagen osteochondral scaffold and ii) to compare the activity of PRP when applied to both collagen- and polylactide-based osteochondral scaffolds.

METHODS

Equal combined volumes of test substances were used (n = 3): 500 μl PRP alone or on scaffolds; 375 μl PRP + 125 μl autologous thrombin on scaffolds; 455 μl PRP + 45 μl bovine thrombin on scaffolds. Scaffolds and/or PRP were cultured in vitro in DMEM/F12 medium for 10 days. TGF-β1, PDGF-AB and bFGF were measured using ELISA.

RESULTS

A similar cumulative release profile in all growth factors was found over the 10-day period i.e. a burst release and further physiological prolonged release. A significantly higher release of PDGF-AB was seen in the PRP + collagen scaffold groups at all time points, compared to scaffold + PRP + thrombins (P < 0.001). A significantly increased cumulative volume of PDGF-AB was released from the collagen scaffold compared to the polylactide scaffold (P < 0.001).

CONCLUSION

This study shows that polylactide and particularly collagen osteochondral scaffolds activate PRP in vitro. If PRP is combined with these scaffolds clinically, no exogenous activation with thrombin is required to achieve growth factor release, which may be of benefit for articular cartilage repair applications.

A novel autologous scaffold for diced-cartilage grafts in dorsal augmentation rhinoplasty

BACKGROUND

Diced-cartilage grafts have been used for dorsal nasal augmentation for several years with good results. However, compounds such as Surgicel and temporalis fascia used as a wrap have inherent problems associated with them, predominantly inflammation and graft resorption. An autologous carrier could provide stabilization of cartilage grafts while avoiding the complications seen with earlier techniques.

METHODS

In our patients, a malleable construct was used for dorsal nasal augmentation in which autologous diced-cartilage grafts were stabilized with autologous tissue glue (ATG) created from platelet-rich plasma (platelet gel) and platelet-poor plasma (fibrin glue).

RESULTS

A prospective analysis of 68 patients, who underwent dorsal nasal augmentation utilizing ATG and diced-cartilage grafts between 2005 and 2008, were included in the study. Although there was notable maintenance of the dorsal height, no complications occurred that required explantation over a mean follow-up of 15 months.

CONCLUSION

The use of ATG to stabilize diced-cartilage grafts is a safe, reliable technique for dorsal nasal augmentation. The platelet gel provides growth factors while the fibrin glue creates a scaffold that allows stabilization and diffusion of nutrients to the cartilage graft.

Immune Responses Associated With Perioperative Exposure and Reexposure to Topical Bovine Thrombin Do Not Impair Hemostasis

Topical bovine thrombin has been associated with immune responses and anecdotal reports of coagulopathy. This open-label study assessed the impact on clinical hemostasis of human antibodies to bovine thrombin (aBT) or factor V/Va (aBV/Va) in response to topical bovine thrombin (THROMBIN-JMI) in patients both with and without preexisting anti-bovine antibodies. Noninferiority analysis assessed primary endpoint for mean shift from baseline activated partial thromboplastin time (aPTT) at 48 hours postsurgery; secondary endpoints included changes from baseline antibodies/titers and coagulation parameters through 8 weeks postsurgery. A total of 550 patients underwent surgery with THROMBIN-JMI utilized at investigator’s discretion. Adjusted mean aPTT change in (+)aBT/(+)THROMBIN-JMI cohort was greater than (-)aBT/(-)THROMBIN-JMI cohort; 4.67-second upper confidence bound exceeded 4.5-second margin (based on assumed mean aPTT of 30 seconds) and noninferiority was not met. Post hoc analysis indicated noninferiority would have been met had noninferiority margin been set prior at relative 15% of actual baseline aPTT. Antibodies/titers were unchanged by THROMBIN-JMI exposure 48 hours postsurgery and unrelated to postsurgical changes in coagulation. Thus, THROMBIN-JMI exposure in patients with/without preexisting aBT or aBV/Va does not alter hemostasis.

Hemostasis in burn surgery--a review

Over the past 30 years, techniques of early excision and grafting along with enhancement of critical care have significantly improved survival following burn injury. Despite these advancements, large volume blood loss associated with surgical intervention continues to be a challenging aspect of burn surgery. This review article will examine the methods of limiting blood loss during surgical procedures.

Safety and Efficacy of Thrombin-JMI: A Multidisciplinary Expert Group Consensus

Background: The use of bovine thrombin has been an effective approach to aiding hemostasis during surgery for over 60 years. Its use has a reported association with the development of antibodies to coagulation factors with limited evidence to the clinical significance. Methods: The Collaborative Delphi survey methodology was used to develop a consensus on specified topic areas from a panel of 12 surgeons/scientists who have had experience with topical thrombins; it consisted of 2 rounds of a Web-based survey and a final live discussion. Results: Some key issues that reached consensus included: bovine, human plasma-derived and recombinant human thrombin are equally effective hemostatic agents with similar adverse event rates, and immunogenicity to a topical protein rarely translate into adverse events. Conclusions: Although a risk of immunogenicity is associated with all topical thrombins, no conclusive clinical evidence is available that these antibodies have any significant effect on short- and long-term clinical consequences.

Cross-reactivity of rabbit anti-bovine prothrombin/thrombin IgGs with bovine factor V/Va-related antigens

The purpose of this study was to determine whether rabbit anti-bovine prothrombin/thrombin immunoglobulin Gs (IgGs) would cross-react with bovine factor V/Va-related antigens. Bovine prothrombin, crude thrombin, as well as 2 purified versions of thrombin, that is, thrombin 4A (the previous version of Thrombin-JMI marketed prior to 2008) and 4B (the currently marketed version of Thrombin-JMI), were administrated to individual groups of rabbits on days 0, 21, 42, 91, 123, and 151 using standard immunologic methods. Blood was drawn from each rabbit on days 30, 50, 105, 137, and 165 and the pooled antisera from individual groups were purified to obtain the IgGs using protein G affinity columns. By probing bovine factor V/Va samples, the possible cross-reactivity of each IgG collected at different time points (from day 30 to day 165) was explored using Western blotting techniques. The results indicated that rabbit anti-bovine prothrombin and crude thrombin IgGs could cross-react strongly with bovine factor V/Va in an immunization time-dependent manner. However, antibodies generated in thrombin 4A-treated rabbits presented much weaker cross-reactivity with bovine factor V/Va. Furthermore, no cross-reactivity with bovine factor V/Va-related antigens was observed when the anti-bovine thrombin 4B IgG collected at any time point was used. The results suggest that thrombin 4B preparation contains the least bovine factor V/Va contaminants among the bovine prothrombin/thrombin preparations studied and the amount of bovine factor V/Va contaminants in bovine thrombin 4B is too small to elicit the generation of antibodies against bovine factor V/Va in rabbits.

The long term immunological response of swine after two exposures to a salmon thrombin and fibrinogen hemostatic bandage

Experimental salmon thrombin/fibrinogen dressings have been shown to provide effective hemostasis in severe hemorrhage situations. The hypothesis for this study was that swine would still remain healthy without coagulopathy six months after exposure to salmon thrombin/fibrinogen dressings. Initial exposure was by insertion of the salmon dressing into the peritoneal cavity. Three months after the initial exposure, the same animals were subjected to two full thickness dermal wounds on the dorsal surface. One wound was bandaged with the salmon thrombin/fibrinogen bandage and the other wound was dressed with a standard bandage. The animals were monitored for an additional three months. Blood was drawn every 14 days over the six months for immunological and coagulation function analysis. All of the animals (8 pigs) remained healthy during the six month period and the dermal wounds healed without incidence. Lymph nodes and spleen showed signs of normal immune response and Western blots showed development of antibodies against salmon fibrinogen, but none of the animals made antibodies that recognized any species of thrombin. Coagulation parameters (fibrinogen concentration, thrombin time, PT and aPTT) and hematological parameters remained normal over the course of the study when compared to initial values of the subject swine.

Adverse drug events associated with disorders of coagulation

Disorders of coagulation are common adverse drug events encountered in critically ill patients and present a serious concern for intensive care unit (ICU) clinicians. Dosing strategies for medications used in the ICU are typically developed for use in noncritically ill patients and, therefore, do not account for the altered pharmacokinetic and pharmacodynamic properties encountered in the critically ill as well as the increased potential for drug-drug interactions, given the far greater number of medications ordered. This substantially increases the risk for coagulation-related adverse reactions, such as a bleeding or prothrombotic events. Although many medications used in the ICU have the potential to cause coagulation disorders, the exact incidence will vary based on the specific medication, dose, concomitant drug therapy, ICU setting, and patient-specific comorbidities. Clinicians must strongly consider these factors when evaluating the risk/benefit ratio for a particular therapy. This review surveys recent literature documenting the risk for adverse drug reactions specific to bleeding and/or clotting with commonly used medications in the ICU.