General haemostatic agents--fact or fiction?

Antifibrinolytic amino acids for upper gastrointestinal bleeding in people with acute or chronic liver disease

BACKGROUND

Upper gastrointestinal bleeding is one of the most frequent causes of morbidity and mortality in the course of liver cirrhosis. People with liver disease frequently have haemostatic abnormalities such as hyperfibrinolysis. Therefore, antifibrinolytic amino acids have been proposed to be used as supplementary interventions alongside any of the primary treatments for upper gastrointestinal bleeding in people with liver diseases. This is an update of this Cochrane review.

OBJECTIVES

To assess the beneficial and harmful effects of antifibrinolytic amino acids for upper gastrointestinal bleeding in people with acute or chronic liver disease.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Controlled Trials Register (February 2015), Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2 of 12, 2015), MEDLINE (Ovid SP) (1946 to February 2015), EMBASE (Ovid SP) (1974 to February 2015), Science Citation Index EXPANDED (1900 to February 2015), LILACS (1982 to February 2015), World Health Organization Clinical Trials Search Portal (accessed 26 February 2015), and the metaRegister of Controlled Trials (accessed 26 February 2015). We scrutinised the reference lists of the retrieved publications.

SELECTION CRITERIA

Randomised clinical trials irrespective of blinding, language, or publication status for assessment of benefits and harms. Observational studies for assessment of harms.

DATA COLLECTION AND ANALYSIS

We planned to summarise data from randomised clinical trials using standard Cochrane methodologies and assessed according to the GRADE approach.

MAIN RESULTS

We found no randomised clinical trials assessing antifibrinolytic amino acids for treating upper gastrointestinal bleeding in people with acute or chronic liver disease. We did not identify quasi-randomised, historically controlled, or observational studies in which we could assess harms.

AUTHORS' CONCLUSIONS

This updated Cochrane review identified no randomised clinical trials assessing the benefits and harms of antifibrinolytic amino acids for upper gastrointestinal bleeding in people with acute or chronic liver disease. The benefits and harms of antifibrinolytic amino acids need to be tested in randomised clinical trials. Unless randomised clinical trials are conducted to assess the trade-off between benefits and harms, we cannot recommend or refute antifibrinolytic amino acids for upper gastrointestinal bleeding in people with acute or chronic liver diseases.

Antifibrinolytic amino acids for upper gastrointestinal bleeding in patients with acute or chronic liver disease

BACKGROUND

Upper gastrointestinal bleeding is one of the most frequent causes of morbidity and mortality in the course of liver cirrhosis. Patients with liver disease frequently have haemostatic abnormalities like hyperfibrinolysis. Therefore, antifibrinolytic amino acids have been proposed to be used as supplementary interventions alongside any of the primary treatments for upper gastrointestinal bleeding in patients with liver diseases.

OBJECTIVES

To assess the beneficial and harmful effects of antifibrinolytic amino acids for upper gastrointestinal bleeding in patients with acute or chronic liver disease.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register (11 June 2012), Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2012, Issue 5 of 12), MEDLINE (Ovid SP) (1946 to June 2012), EMBASE (Ovid SP) (1974 to June 2012), Science Citation Index EXPANDED (1900 to June 2012), LILACS (1982 to June 2012), Clinical Trials Search Portal of the WHO (accessed June 18, 2012), and the Metaregister of Controlled Trials (accessed June 18, 2012). We scrutinised the reference lists of the retrieved publications.

SELECTION CRITERIA

Randomised clinical trials irrespective of blinding, language, or publication status for assessment of benefits and harms. Observational studies for assessment of harms.

DATA COLLECTION AND ANALYSIS

Data from randomised clinical trials were to be summarised by standard Cochrane Collaboration methodologies.

MAIN RESULTS

We could not find any randomised clinical trials assessing antifibrinolytic amino acids for treating upper gastrointestinal bleeding in patients with acute or chronic liver disease. We could not identify quasi-randomised, historically controlled, or observational studies in which we could assess harms.

AUTHORS' CONCLUSIONS

No randomised clinical trials assessing the benefits and harms of antifibrinolytic amino acids for upper gastrointestinal bleeding in patients with acute or chronic liver disease were identified. The benefits and harms of antifibrinolytic amino acids need to be tested in randomised clinical trials. Unless randomised clinical trials are conducted to assess the trade off between benefits and harms, we cannot recommend nor refute antifibrinolytic amino acids for upper gastrointestinal bleeding in patients with acute or chronic liver diseases.

Preclinical toxicity biomarkers for combination treatment with clotting factors rFXIII and rFVIIa

Combination treatment with the clotting factors recombinant activated factor VII (rFVIIa), serine protease, and recombinant factor XIII (rFXIII), protransglutaminase, is being explored for haemostatic therapy. We performed a single-dose toxicology study in the cynomolgus monkey, with four dose groups receiving 0.1 + 0.34 mg kg(-1) (group 1), 0.33 + 1.12 mg kg(-1) (group 2), 1.67 + 5.60 mg kg(-1) (group 3) and 5.00 + 16.80 mg kg(-1) (group 4) of a rFVIIa + rFXIII combination. In the three lower dose groups, no clinical, histopathological or blood chemistry changes were observed. In group 4, the animals died at 4 h post-dosing, with histopathology revealing a systemic coagulopathy resembling, but distinct from, disseminated intravascular coagulation. Due to the absence of toxicity warning signs, toxicity biomarkers were identified by a Western blot-based screening of approximately 20 plasma proteins known to be involved in the clotting cascade. Three of the examined proteins were specifically affected by rFVIIa + rFXIII treatment. Fibronectin and fibrinogen exhibited dose-dependent reductions from less than 10% reduction (group 2) to more than 90% reduction (group 4). These reductions were reversible, and specific. For vitronectin, a dose-dependent conversion to the 65-kDa form was found to occur in groups 3 and 4. Thus, fibrinogen, fibronectin and vitronectin represent the first biomarkers for clotting factor toxicity.

Cardiovascular disease and heritability of the prothrombotic state

Atherothrombotic disease remains a major cause of mortality worldwide, and family clustering suggests an important contribution of genetic factors to disease pathogenesis. Thrombus formation represents the final step in atherothrombosis, a process influenced by genetic and environmental factors. A major difficulty of investigating the genetic regulation of thrombotic conditions is the complexity of the phenotype and the relatively modest effects of individual genetic variations. We address in this review genetic aspects involved in regulating thrombosis potential and their impact on the development of atherothrombotic disease. The effects of common genetic polymorphisms in clotting factors are discussed and examples of complex gene-gene and gene-environment interactions are highlighted. Understanding the effects of genetic factors on predisposition to thrombotic disease and unravelling the complex gene-environment interactions will help to better understand the pathophysiology of this complex condition, which will enable the development of new preventative and treatment strategies.

Antifibrinolytic amino acids for acquired coagulation disorders in patients with liver disease

BACKGROUND

Upper gastrointestinal bleeding is one of the most frequent causes of morbidity and mortality in the course of liver cirrhosis. Patients with liver disease frequently have haemostatic abnormalities, which include accelerated fibrinolysis. Several primary treatments are used for upper gastrointestinal bleeding in patients with liver diseases. Supplementary interventions are often used as well. One of them could be antifibrinolytic amino acids administration.

OBJECTIVES

To assess the beneficial and harmful effects of antifibrinolytic amino acids for upper gastrointestinal bleeding in patients with acute or chronic liver disease plus acquired coagulation disorders.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register (March 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 1, 2006), MEDLINE (1950 to March 2006), EMBASE (1980 to March 2006), Science Citation Index EXPANDED (1945 to March 2006), LILACS (1982 to March 2006), ClinicalTrials.gov (at www.clinicaltrials.gov) (accessed August 2006), ISI Web of Science (April 2006), and the International Standard Randomised Controlled Trial Number Register (at http://controlled-trials.com/isrctn/search.asp) (accessed August 2006). We also checked the reference lists of all the trials identified by the above methods.

SELECTION CRITERIA

We searched for randomised clinical trials irrespective of blinding, language, or publication status.

DATA COLLECTION AND ANALYSIS

We intended to summarise data by standard Cochrane Collaboration methodologies.

MAIN RESULTS

We could not find any randomised clinical trials with antifibrinolytic amino acids for upper gastrointestinal bleeding in patients with acute or chronic liver disease plus acquired coagulation disorders.

AUTHORS' CONCLUSIONS

We were unable to identify randomised clinical trials on the safety and efficacy of antifibrinolytic amino acids for upper gastrointestinal bleeding in patients with liver disease (acute or chronic) plus acquired coagulation disorders. The effects of antifibrinolytic amino acids has to be tested in randomised clinical trials.

Reversal of low-molecular-weight heparin-induced bleeding in patients with pre-existing hypercoagulable states with human recombinant activated factor VII concentrate

Low-molecular-weight heparins are widely employed in prophylactic and therapeutic antithrombotic regimens for venous thromboembolic events. Excessive anticoagulation with low-molecular-weight heparins rarely can precipitate catastrophic bleeding complications. Currently, there is no specific or reliable antidote that can reverse the anticoagulant effects of low-molecular-weight heparins efficiently and safely. This report describes three individuals with underlying hypercoagulable states, who developed clinically significant bleeding complications while receiving therapeutic anticoagulation with enoxaparin. All of the hemorrhagic events subsequently were safely and effectively reversed with a single intravenous bolus infusion of recombinant activated factor VIIa (RFVIIa) concentrate. Hemoglobins, prothrombin times, and clinical overt bleeding were monitored before and after the administration of RFVIIa. In all three cases, bleeding was controlled without an increase in thrombotic events. Our findings demonstrate that RFVIIa can rapidly and safely reverse the hemorrhagic adverse effects associated with excessive levels of low-molecular-weight heparin in patients with pre-existing hypercoagulable conditions and/or acute venous thromboembolism.

Coagulation and atherothrombotic disease

Atherothrombotic disease arises secondary to a complex gene-environment interaction. In the initial stages, the condition is clinically silent but with more advanced disease, an occlusive thrombus is formed resulting in the classical clinical manifestations. Both environmental factors and genetic variations in elements of the clotting cascade influence thrombosis risk by inducing quantitative and qualitative changes in the mature protein, which may affect the final structure of the clot and determine its resistance to lysis. Understanding the fine details of gene-environment interactions in relation to thrombus formation will help to shed more light on disease pathogenesis. Consequently, this will allow the development of more efficacious treatment strategies and will also help to identify subjects at risk, thereby enabling the introduction of early preventative measures.

A capillary hemostasis mechanism regulated by sympathetic tone and activity via factor VIII or von Willebrand's factor may function as a "capillary gate" and may explain angiodysplasia, angioneurotic edema, and variations in systemic vascular resistance

The sympathetic nervous system (SNS) may directly or indirectly govern the release of von Willebrand's factor (VWB), which may be a hormone, from the vascular endothelium, which may be a gland. VWB is known to stabilize the labile VIIIC component of Factor VIII complex, and may thereby determine its half-life and activity level in the blood. Rising blood levels of Factor VIII may increase the speed of thrombin production during the "propagation" phase of blood coagulation and thereby elevate peak levels and duration of thrombin activity to produce and stabilize insoluble fibrin in quantities necessary to initiate clot formation. At the capillary level, microvascular receptor sites may bring fibrinogen and fibronectin, which are basic "building blocks" of insoluble fibrin, into close proximity with rising levels of Factor VIII to facilitate insoluble fibrin production and serve as binding sites for an expanding mass of insoluble fibrin that adheres to blood components to cause capillary hemostasis. Capillary hemostasis may serve as a "capillary gate mechanism" (CGM) that increases systemic vascular resistance and blood pressure and decreases cardiac output in accord with increased tone and activity levels of the SNS by obstructing capillary bed flow. Angiodysplasia may be caused by persistent defects in the VWB molecule that impair CGM function and cause visible capillary damage. Angioneurotic edema may be caused by sudden complement system attack on VWB that results in widespread paralysis of CGM function and sudden shift of blood from arteries and arterioles to capillaries to cause tissue edema and hypotension. The hypothesis may offer improved insight into the nature of circulatory physiology, the surgical stress syndrome, "vasoactive" drugs, and numerous disease states. It may be tested by using videomicroscopy to monitor changes in bowel capillary flow in response to stepwise increases of VWB or Factor VIII intravenous boluses in animals anesthetized using combined epidural-general technique to minimize SNS activity levels.

Potential uses of recombinant human factor VIIa in veterinary medicine

In human beings, rFVIIa has been used successfully to promote hemostasis in patients with various bleeding disorders. Patients with hemophilia, thrombocytopenia, and thrombocytopathy have been effectively and safely treated as well as patients with severe trauma or surgery resulting in profuse bleeding and patients with impaired liver function. Given these successes, the possibility of using rFVIIa in veterinary medicine is appealing. The clinical indications and uses in veterinary medicine would be similar, but there are currently two major obstacles: immunogenicity and cost. If these problems can be addressed, rFVIIa may become a valuable and indispensable therapy, especially in the emergency and critical care settings. The use of rFVIIa could allow for successful treatment of otherwise intractable bleeding as well as decrease the number of blood transfusions needed.