Factor V inhibitor after injection of human thrombin (tissucol) into a bleeding peptic ulcer

Bridging wounds: tissue adhesives' essential mechanisms, synthesis and characterization, bioinspired adhesives and future perspectives

Bioadhesives act as a bridge in wound closure by forming an effective interface to protect against liquid and gas leakage and aid the stoppage of bleeding. To their credit, tissue adhesives have made an indelible impact on almost all wound-related surgeries. Their unique properties include minimal damage to tissues, low chance of infection, ease of use and short wound-closure time. In contrast, classic closures, like suturing and stapling, exhibit potential additional complications with long operation times and undesirable inflammatory responses. Although tremendous progress has been made in the development of tissue adhesives, they are not yet ideal. Therefore, highlighting and summarizing existing adhesive designs and synthesis, and comparing the different products will contribute to future development. This review first provides a summary of current commercial traditional tissue adhesives. Then, based on adhesion interaction mechanisms, the tissue adhesives are categorized into three main types: adhesive patches that bind molecularly with tissue, tissue-stitching adhesives based on pre-polymer or precursor solutions, and bioinspired or biomimetic tissue adhesives. Their specific adhesion mechanisms, properties and related applications are discussed. The adhesion mechanisms of commercial traditional adhesives as well as their limitations and shortcomings are also reviewed. Finally, we also discuss the future perspectives of tissue adhesives.

The recent progress of tissue adhesives in design strategies, adhesive mechanism and applications

Tissue adhesives have emerged as an effective method for wound closure and hemostasis in recent decades, due to their ability to bond tissues together, preventing separation from one tissue to another. However, existing tissue adhesives still have several limitations. Tremendous efforts have been invested into developing new tissue adhesives by improving upon existing adhesives through different strategies. Therefore, highlighting and analyzing these design strategies are essential for developing the next generation of advanced adhesives. To this end, we reviewed the available strategies for modifying traditional adhesives (including cyanoacrylate glues, fibrin sealants and BioGlue), as well as design of emerging adhesives (including gelatin sealants, methacrylated sealants and bioinspired adhesives), focusing on their structures, adhesive mechanisms, advantages, limitations, and current applications. The bioinspired adhesives have numerous advantages over traditional adhesives, which will be a wise direction for achieving tissue adhesives with superior properties.

Acquired factor V inhibitor after exposure to topical human thrombin related to an otorhinolaryngological procedure

Acquired factor V (FV) inhibitors occur rarely and classically develop after exposure to bovine thrombin. The clinical presentation is variable, ranging from asymptomatic with incidental laboratory abnormalities to significant bleeding. With the development of human-derived thrombin agents, bovine thrombin is less frequently used. We report a case of an acquired FV inhibitor that developed in a patient after exposure to human thrombin used as a hemostatic agent during an otorhinolaryngology surgical procedure. Our review of the literature revealed only one prior reported case of FV inhibitor after exposure to human thrombin. Hematologists and surgeons should be aware of this rare, but potentially life-threatening, complication in the postprocedural setting.

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.

Relative purity of different bovine thrombin preparations

The aim of this study was to compare the relative purity of bovine crude thrombin and its purified forms, namely, thrombin 4A and thrombin 4B (the products of King Pharma, Middleton, Wisconsin) by virtue of the detection of bovine prothrombin-related antigens in these preparations. Bovine prothrombin was administered intravenously to 3 individual rabbits on days 0, 21, 42, 91, 123, and 151 using standard immunologic method. Blood was drawn from each rabbit on days 30, 50, 105, 137, and 165, and the pooled antisera from 3 rabbits were purified to isolate immunoglobulin G (IgG) using protein G affinity columns. Using Western blotting method, serially diluted bovine crude thrombin, thrombin 4A, and 4B preparations were probed using the prothrombin IgGs obtained from each time point to explore prothrombin-related antigens in these preparations. The results revealed that compared with the prothrombin IgG collected on day 30, the IgGs collected on days 50 to 165 showed a time-dependent increase in their ability to detect the prothrombin-related antigens in 3 bovine thrombin preparations studied. The lowest amount of crude thrombin, thrombin 4A, and 4B preparations that prothrombin IgG could detect was 0.125, 10, and 20 U, respectively. The rank order of the number of immunoreactive bands detectable in 3 bovine thrombin preparations probed by the prothrombin IgGs collected from any given time point was always the same: crude thrombin > thrombin 4A > thrombin 4B. The results indicate that thrombin 4B preparation contains the least amount of antigens detectable by prothrombin IgG, suggesting that relatively thrombin 4B represents the most purified thrombin preparation among the 3 thrombin preparations studied.

Building an immune-mediated coagulopathy consensus: early recognition and evaluation to enhance post-surgical patient safety

Topical hemostats, fibrin sealants, and surgical adhesives are regularly used in a variety of surgical procedures involving multiple disciplines. Generally, these adjuncts to surgical hemostasis are valuable means for improving wound visualization, reducing blood loss or adding tissue adherence; however, some of these agents are responsible for under-recognized adverse reactions and outcomes. Bovine thrombin, for example, is a topical hemostat with a long history of clinical application that is widely used alone or in combination with other hemostatic agents. Hematologists and coagulation experts are aware that these agents can lead to development of an immune-mediated coagulopathy (IMC). A paucity of data on the incidence of IMC contributes to under-recognition and leaves many surgeons unaware that this clinical entity, originating from normal immune responses to foreign antigen exposure, requires enhanced post-operative vigilance and judicious clinical judgment to achieve best outcomes.

Postoperative bleeding may result from issues such as loosened ties or clips or the occurrence of a coagulopathy due to hemodilution, vitamin K deficiency, disseminated intravascular coagulation (DIC) or post-transfusion, post-shock coagulopathic states. Other causes, such as liver disease, may be ruled out by a careful patient history and common pre-operative liver function tests. Less common are coagulopathies secondary to pathologic immune responses. Such coagulopathies include those that may result from inherent patient problems such as patients with an immune dysfunction related to systemic lupus erythrematosus (SLE) or lymphoma that can invoke antibodies against native coagulation factors. Medical interventions may also provoke antibody formation in the form of self-directed anti-coagulation factor antibodies, that result in problematic bleeding; it is these iatrogenic post-operative coagulopathies, including those associated with bovine thrombin exposure and its clinical context, that this panel was convened to address.

The RETACC panel's goal was to attain a logical consensus by reviewing the scientific evidence surrounding IMC and to make recommendations for the clinical recognition, diagnosis and evaluation, and clinical management of these complications. In light of the under-recognition and under-reporting of IMC, and given the associated morbidity, utilization of health care resources, and potential economic impact to hospitals, the panel engaged in a detailed review of peer-reviewed reports of bovine thrombin associated IMC. From that clinical knowledge base, recommendations were developed to guide clinicians in the recognition, diagnosis, and management of this challenging condition.

Topical bovine thrombin and adverse events: a review of the literature

OBJECTIVE

To review published evidence suggesting a link between topical bovine thrombin (TBT) and important adverse events (AEs).

RESEARCH DESIGN AND METHODS

English language articles and abstracts were obtained from MEDLINE using combinations of text and MeSH terms for thrombin, bovine thrombin and their trade names. References from summary articles were also retrieved. Published case reports, review articles, and retrospective, prospective or observational studies involving either immunogenicity or AEs were selected for further assessment. Retrieved articles were evaluated separately as AE case reports, quantitative studies of antibodies, or quantitative studies of AEs.

MAIN OUTCOME MEASURES

Presence of case causal information, temporal pattern of case report publication, reproducibility of aggregate data findings, and study design features.

RESULTS

The major limitations of reviewed publications were insufficient information regarding TBT and other exposures, and designs in which linkage between laboratory immune phenomena and AEs could not be evaluated. While immunogenicity studies did support an increased risk for post-TBT antibodies, there was no consistent evidence that this led to an increased AE risk or severity. Common evidentiary deficiencies included case reports from high incidence environments, studies of combination or mixture products, biased study designs, lack of patient-level exposure data, inadequate control groups and insufficient sample sizes. The best designed study (a randomized, controlled comparison of TBT to a recombinant bovine product) documented post-TBT antibody production, but no important efficacy or AE differences. An examination of publication dates for case reports showed a peak between 1992 and 1994 followed by a substantial drop. Since 1997 the number of published AE case reports has continued to decline.

CONCLUSIONS

TBT increases the risk for antibody elevations in patients. A careful review of published evidence does not show that either TBT itself or any associated elevations in anti-bovine antibodies are risk factors for clinically important AEs.

Risk of bleeding in surgical patients treated with topical bovine thrombin sealants: a review of the literature

BACKGROUND

One of the most anticipated, but potentially serious complications during or after surgery are bleeding events. Among the many potential factors associated with bleeding complications in surgery, the use of bovine thrombin has been anecdotally identified as a possible cause of increased bleeding risk. Most of these reports of bleeding events in association with the use of topical bovine thrombin have been limited to case reports lacking clear cause and effect relationship determination. Recent studies have failed to establish significant differences in the rates of bleeding events between those treated with bovine thrombin and those treated with either human or recombinant thrombin.

METHODS

We conducted a search of MEDLINE for the most recent past 10 years (1997-2007) and identified all published studies that reported a study of surgical patients with a clear objective to examine the risk of bleeding events in surgical patients. We also specifically noted the reporting of any topical bovine thrombin used during surgical procedures. We aimed to examine whether there were any differences in the risk of bleeds in general surgical populations as compared to those studies that reported exposure to topical bovine thrombin.

RESULTS

We identified 21 clinical studies that addressed the risk of bleeding in surgery. Of these, 5 studies analyzed the use of bovine thrombin sealants in surgical patients. There were no standardized definitions for bleeding events employed across these studies. The rates of bleeds in the general surgery studies ranged from 0.1%-20.2%, with most studies reporting rates between 2.6%-4%. The rates of bleeding events ranged from 0.0%-13% in the bovine thrombin studies with most studies reporting between a 2%-3% rate.

CONCLUSION

The risk of bleeds was not clearly different in those studies reporting use of bovine thrombin in all patients compared to the other surgical populations studied. A well-designed and well-controlled study is needed to accurately examine the bleeding risks in surgical patients treated and unexposed to topical bovine thrombin, and to evaluate the independent risk associated with topical bovine thrombin as well as other risk factors.

Factor V inhibitor: case report

Acquired inhibitors to coagulation factors are rare, certainly those directed against factor V. A total of around 150 cases have so far been reported, of which the greater part was due to bovine thrombin exposure. We report the case of a patient who developed a factor V inhibitor during a postoperative period. This report describes possible aetiologies, varying clinical conditions and treatment possibilities as described in the literature. Furthermore, this case report is an example of the often unpredictable disease progression in a patient with existence of a factor V inhibitor.

Risk reduction of subdural collections following endoscopic third ventriculostomy

OBJECT

To evaluate the efficacy and safety using fibrin glue and absorbable hemostats for packing the endoscopic tract in a pediatric population in the prevention of subdural fluid collections after endoscopic third ventriculostomy.

MATERIALS AND METHODS

Twenty-one endoscopic third ventriculostomies were performed in 20 hydrocephalic children with a mean age of 22 months over a 4-year period using uniformly this technique. Six children, with age ranged 6 days to 22 months (mean 9 months), had severe ventriculomegaly with thin brain mantle less than 10 mm. There was no mortality and no permanent morbidity related to the endoscopic procedure. One child developed an asymptomatic collection, which could be managed conservatively and was most likely attributed to the young age of the child and the assumed poor cerebrospinal fluid absorption ability. Lost compliance of the brain parenchyma may play an additional role, which was not related to the thickness of the brain mantle. No adverse effects regarding the material used for sealing were observed over a mean follow-up of 23 months.

CONCLUSIONS

Subdural fluid collections could be prevented in 20 out of 21 procedures by using this technique regardless of the thickness of the brain mantle, the application of mixture of fibrin glue and hemostatic agents seems to be safe, and we consider this technique effective in reducing the risk of this potential complication.

Spectrum of bleeding in acquired factor V inhibitor: a summary of 33 cases

Coagulation factor V (FV) is an essential component of the prothrombinase complex, which activates the zymogen prothrombin to thrombin. Acquired FV inhibitor is rare and clinical symptoms are quite variable. The aim of this study was to summarize the spectrum of the bleeding presentation of acquired FV deficiency and characterize the underlying causes of the clinical symptoms. This study was designed as a descriptive retrospective and 30 case reports were included for further analysis. At least 33 cases of acquired FV inhibitor were investigated. Most patients have a presentation of bleeding and most of those are from hematuria and bleeding at surgical sites. Seven cases of asymptomatic acquired FV inhibitor were also detected. A total of 39.4% (19 of 33) of those cases with acquired FV inhibitor have an unknown cause. For those with known etiologies, chemical and drug-induced causes are the most common (30.8%).

A Salmon Thrombin-Fibrin Bandage Controls Arterial Bleeding in a Swine Aortotomy Model

BACKGROUND

Recently, a wide variety of bandages have been formulated to attempt to improve the effectiveness of emergency intervention in situations of uncontrolled bleeding. The best of these dressings contain a mixture of human thrombin and fibrinogen. The presence of human components in these bandages, although effective, increases the cost of the dressing and raises questions of availability of raw materials and transmission of pathogens. The purpose of this study was to investigate the efficacy of dressings composed of salmon thrombin and fibrinogen in a swine aortotomy model.

METHODS

A 4.4-mm aortotomy was produced in the abdominal aorta of 19 anesthetized, splenectomized swine. The United States Army standard field gauze was applied to 8 animals, and the salmon thrombin-fibrin dressing (SFD) was applied to 11 animals. Survival, blood loss, and other parameters were measured over a 60-minute period.

RESULTS

All 11 animals that received the SFD survived the aortotomy injury, and bleeding stopped within 7.5 +/- 1.5 min. Seven of 8 animals in the control group were killed when bleeding continued and blood pressures decreased to the cutoff values as outlined in the animal protocol. Bleeding was significantly less in the SFD group compared with the gauze group (241 +/- 65.3 vs. 932.7 +/- 142.4 mL).

CONCLUSION

Fibrin dressing using salmon-derived thrombin and fibrinogen is effective in controlling severe, uncontrolled bleeding. This dressing may offer an alternative to dressings composed of human coagulation proteins.

Factor V inhibitors

Acquired deficiencies of, or inhibitors to, factor V are considered rare events. We report a series of 14 acquired factor V deficiencies, 10 of which were confirmed to have inhibitors to factor V, as identified within Australia in the past 5 years following a multi-laboratory investigation. The initial index case seen by one laboratory was followed within 4 months by a separate similar case. This prompted local contact with colleagues (n = 20) working in other haemostasis referral laboratories to identify the current case series. In total, nearly one-half of all haemostasis referral laboratories contacted had seen a case within the past 5 years. Clinical features and the apparent associated risk of bleeding complications generally varied, as did laboratory findings and the likely causal event. There were three females and 11 males. Age ranged from 44 to 95 years (median, 81 years). The level of inhibitor ranged from undetectable to over 250 Bethesda units. The probable cause leading to development of the inhibitors ranged from exposure to bovine thrombin, exposure to antibiotics, surgery and malignancy. Of additional interest was the apparent association of anti-phospholipid antibodies in many of the cases. For example, in the two similar index cases, with factor V inhibitor titres > 200 Bethesda units, high levels of anti-cardiolipin antibodies (> 70 GPL units) were also detected. Although less clear because of inhibitor interference, many of the cases also showed evident co-associated lupus anticoagulant activity. In conclusion, we report a series of factor V inhibitors recently identified within our geographic region that would represent an annual incidence of around 0.29 cases per million Australians. Although considered a rare finding, there is a high likelihood that most haemostasis referral laboratories will see a case every five or so years.