Basis of antifibrinolytic therapy

A high-dose 24-hour tranexamic acid infusion for the treatment of significant gastrointestinal bleeding: HALT-IT RCT

BACKGROUND

Tranexamic acid reduces blood loss in surgery and the risk of death in trauma patients. Meta-analyses of small trials suggest that tranexamic acid decreases the number of deaths from gastrointestinal bleeding, but these meta-analyses are prone to selection bias.

OBJECTIVE

The trial provides reliable evidence of the effect of tranexamic acid on mortality, rebleeding and complications in significant acute gastrointestinal bleeding.

DESIGN

A multicentre, randomised, placebo-controlled trial and economic analysis. Patients were assigned by selecting one treatment pack from a box of eight, which were identical apart from the pack number. Patients, caregivers and outcome assessors were masked to allocation. The main analyses were by intention to treat.

SETTING

The setting was 164 hospitals in 15 countries, co-ordinated from the London School of Hygiene & Tropical Medicine.

PARTICIPANTS

Adults with significant upper or lower gastrointestinal bleeding (n = 12,009) were eligible if the responsible clinician was substantially uncertain about whether or not to use tranexamic acid. The clinical diagnosis of significant bleeding implied a risk of bleeding to death, including hypotension, tachycardia or signs of shock, or urgent transfusion, endoscopy or surgery.

INTERVENTION

Tranexamic acid (a 1-g loading dose over 10 minutes, then a 3-g maintenance dose over 24 hours) or matching placebo.

MAIN OUTCOME MEASURES

The primary outcome was death due to bleeding within 5 days of randomisation. Secondary outcomes were all-cause and cause-specific mortality; rebleeding; need for endoscopy, surgery or radiological intervention; blood product transfusion; complications; disability; and days spent in intensive care or a high-dependency unit.

RESULTS

A total of 12,009 patients were allocated to receive tranexamic acid (n = 5994, 49.9%) or the matching placebo (n = 6015, 50.1%), of whom 11,952 (99.5%) received the first dose. Death due to bleeding within 5 days of randomisation occurred in 222 (3.7%) patients in the tranexamic acid group and in 226 (3.8%) patients in the placebo group (risk ratio 0.99, 95% confidence interval 0.82 to 1.18). Thromboembolic events occurred in 86 (1.4%) patients in the tranexamic acid group and 72 (1.2%) patients in the placebo group (risk ratio 1.20, 95% confidence interval 0.88 to 1.64). The risk of arterial thromboembolic events (myocardial infarction or stroke) was similar in both groups (0.7% in the tranexamic acid group vs. 0.8% in the placebo group; risk ratio 0.92, 95% confidence interval 0.60 to 1.39), but the risk of venous thromboembolic events (deep-vein thrombosis or pulmonary embolism) was higher in tranexamic acid-treated patients than in placebo-treated patients (0.8% vs. 0.4%; risk ratio 1.85, 95% confidence interval 1.15 to 2.98). Seizures occurred in 38 patients who received tranexamic acid and in 22 patients who received placebo (0.6% vs. 0.4%, respectively; risk ratio 1.73, 95% confidence interval 1.03 to 2.93). In the base-case economic analysis, tranexamic acid was not cost-effective and resulted in slightly poorer health outcomes than no tranexamic acid.

CONCLUSIONS

Tranexamic acid did not reduce death from gastrointestinal bleeding and, although inexpensive, it is not cost-effective in adults with acute gastrointestinal bleeding.

FUTURE WORK

These results caution against a uniform approach to the management of patients with major haemorrhage and highlight the need for randomised trials targeted at specific pathophysiological processes.

LIMITATIONS

Although this is one of the largest randomised trials in gastrointestinal bleeding, we cannot rule out a modest increase or decrease in death due to bleeding with tranexamic acid.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN11225767, ClinicalTrials.gov NCT01658124 and EudraCT 2012-003192-19.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 58. See the NIHR Journals Library website for further project information.

Aminocaproic Acid for the Reversal of Alteplase: A Case Series

INTRODUCTION

The evidence to support the use of aminocaproic acid for reversal of alteplase is limited to case reports. Current guidelines recommend cryoprecipitate as first-line treatment, or an antifibrinolytic if cryoprecipitate is unavailable or cannot be used. This case series describes the use of aminocaproic acid for alteplase-related hemorrhage.

MATERIALS AND METHODS

Patients who received aminocaproic acid within 48 hours of alteplase from January 1, 2014, to June 30, 2017 were included. Patients were excluded if aminocaproic acid was not administered for an alteplase-related hemorrhage. Thromboembolic complications at 14 days and hemostasis within 24 hours were documented.

RESULTS

Sixteen patients received aminocaproic acid for an alteplase-related hemorrhage. Aminocaproic acid was given for hemorrhagic conversion of acute ischemic stroke in 7 of 16 patients and other types of hemorrhages in the remaining patients. Hemostasis occurred in 3 of 10 evaluable patients. Overall mortality was 63% (10/16). Administration of aminocaproic acid varied significantly (50% bolus, 12.5% infusion, 37.5% bolus plus infusion). One of 6 evaluable patients had a thromboembolic event. All patients received concomitant blood products. Cryoprecipitate was administered in 69% (11/16) of patients.

CONCLUSIONS

There was no clear relationship between the timing or dose of aminocaproic acid and hemostasis, and it is unclear if administration of aminocaproic acid contributes to hemostasis.

Investigating the Life Expectancy and Proteolytic Degradation of Engineered Skeletal Muscle Biological Machines

A combination of techniques from 3D printing, tissue engineering and biomaterials has yielded a new class of engineered biological robots that could be reliably controlled via applied signals. These machines are powered by a muscle strip composed of differentiated skeletal myofibers in a matrix of natural proteins, including fibrin, that provide physical support and cues to the cells as an engineered basement membrane. However, maintaining consistent results becomes challenging when sustaining a living system in vitro. Skeletal muscle must be preserved in a differentiated state and the system is subject to degradation by proteolytic enzymes that can break down its mechanical integrity. Here we examine the life expectancy, breakdown, and device failure of engineered skeletal muscle bio-bots as a result of degradation by three classes of proteases: plasmin, cathepsin L, and matrix metalloproteinases (MMP-2 and MMP-9). We also demonstrate the use of gelatin zymography to determine the effects of differentiation and inhibitor concentration on protease expression. With this knowledge, we are poised to design the next generation of complex biological machines with controllable function, specific life expectancy and greater consistency. These results could also prove useful for the study of disease-specific models, treatments of myopathies, and other tissue engineering applications.

The Efficacy of Combined Use of Rivaroxaban and Tranexamic Acid on Blood Conservation in Minimally Invasive Total Knee Arthroplasty a Double-Blind Randomized, Controlled Trial

BACKGROUND

Tranexamic acid (TXA) was reportedly to decrease postoperative blood loss after standard total knee arthroplasty (TKA). However, the blood-conservation effect of TXA in minimally invasive TKA, in particular, receiving a direct oral anticoagulant was unclear. The aim of the study was to investigate the efficacy of combined use of TXA and rivaroxaban on postoperative blood loss in primary minimally invasive TKA.

METHODS

In a prospective, randomized, controlled trial, 198 patients were assigned to placebo (98 patients, normal saline injection) and study group (100 patients, 1g TXA intraoperative injection) during primary unilateral minimally invasive TKA. All patients received rivaroxaban 10 mg each day for 14 doses postoperatively. Total blood loss was calculated from the maximum hemoglobin drop after surgery plus amount of transfusion. The transfusion rate and wound complications were recorded in all patients. Deep-vein thrombosis was detected by ascending venography of the leg 15 days postoperatively.

RESULTS

The mean total blood loss was lower in the study group (1020 mL [95% confidence interval, 960-1080 mL]) compared with placebo (1202 mL [95% confidence interval, 1137-1268 mL]) (P < .001). The transfusion rate was lower in the study group compared with placebo (1% vs 8.2%, P = .018). Postoperative wound hematoma and ecchymosis were higher in placebo than the study group (P = .003). There was no symptomatic deep-vein thrombosis or pulmonary embolism in either group.

CONCLUSION

Systemic administration of TXA can effectively reduce the postoperative blood loss which results in lower rate of transfusion requirement and wound hematoma in minimally invasive TKA patients when rivaroxaban is used for thromboprophylaxis. Rivaroxaban has a high rate of bleeding complications when used alone in TKA patients.

Comparison of efficacy and safety of topical versus intravenous tranexamic acid in total hip arthroplasty: A meta-analysis

BACKGROUND

The study aimed to compare the effectiveness and safety of topical versus intravenous (IV) tranexamic acid (TXA) for reducing blood loss in primary total hip arthroplasty (THA).

METHODS

This systematic review and meta-analysis were performed according to the preferred reporting items for systematic reviews and meta-analyses statement criteria. PubMed, Embase, the Cochrane Library, Web of Science, Chinese Biomedicine Literature (CBM), Wanfang Database, China National Knowledge Infrastructure (CNKI), and Google Scholar were searched for randomized controlled trials (RCTs) and non-RCTs that compare topical versus IV-TXA administration for reducing blood loss during TKA from their inception to February, 2016. Meta-analysis was performed by Stata 12.0 software.

RESULTS

Seven studies comprising 2056 patients were included in this meta-analysis. No significant difference is found between topical TXA groups and IV-TXA groups regarding transfusion requirements (RR = 1.37, 95% confidence interval [CI]: 0.96-1.97, P = 0.083), total blood loss (MD 17.09, 95% CI: -33.74-67.91, P = 0.510), and hemoglobin decline (MD 0.32, 95%CI: -0.04-0.69, P = 0.122). Meanwhile, there is no significant difference in terms of the occurrence of deep venous thrombosis (RR = 1.09, 95% CI: 0.40-3.90, P = 0.869).

CONCLUSION

Topical TXA has a similar efficacy to IV-TXA in reducing both blood loss and transfusion rate without sacrificing safety in primary THA.

Intravenous versus topical tranexamic acid in primary total hip replacement: A systemic review and meta-analysis

OBJECTIVE

Total hip arthroplasty (THA) is associated with substantial blood loss. Tranexamic acid (TXA) could reduce perioperative blood loss. The optimal administration routine of TXA remains controversial. The objective of the present systemic review and meta-analysis was to compare the effectiveness and safety of various application methods of tranexamic acid in primary THA.

METHODS

Potential relevant literature was identified from electronic databases including Medline, PubMed, Embase, ScienceDirect, web of science and Cochrane Library. Grey academic studies were also identified from the references of the included literature. There was no language restriction. The pooling of data was carried out by using RevMan 5.1.

RESULTS

Three randomized controlled trials (RCTs) and two non-RCTs involving 1614 patients met the inclusion criteria. Current meta-analysis indicated that there were no significant differences in terms of total blood loss (MD = -30.04, 95% CI: -114.67 to 54.59, P = 0.49), postoperative hemoglobin level (MD = -0.29, 95% CI: -0.68 to 0.10, P = 0.14), transfusion rate (RD = -0.02, 95% CI: -0.5 to -0.00, P = 0.09), length of stay ((MD = -0.14, 95% CI: -0.30 to 0.01, P = 0.07) or operation time ((MD = 1.00, 95% CI: -0.31 to 2.31, P = 0.14) between treatment groups. No significant differences were found regarding the incidence of adverse effects such as wound infection (RD = -0.01, 95% CI: -0.06 to 0.04, P = 0.66), myocardial infarction (MI) (RD = -0.01, 95% CI: -0.04 to 0.02, P = 0.61), deep venous thrombosis (DVT) (RD = 0.00, 95% CI: -0.01 to 0.01, P = 0.51) or pulmonary embolism (PE) (RD = RD = 0.00, 95% CI: -0.01 to 0.01, P = 0.63) between groups.

CONCLUSION

The topical administration of TXA in THA carried similar hemostasis effects compared with intravenous use without an increased risk of thrombotic complications. No other adverse effect was identified. Topical TXA application was a simple, safe, effective and cost-effective adjunct for blood management following primary THA. For patients with a high risk of thromboembolic events, there may be benefits with topical administration.

Late postoperative massive bleeding in septorhinoplasty: A prospective study

Background

There are various complications that can occur in septorhinoplasty, most of which are related to postoperative failure to achieve the desired aesthetic result. However, there are also many other complications, including postoperative bleeding, which is one of the most common nonaesthetic-related complications.

Objective

The present study was a prospective analysis involving a total of 750 septorhinoplasty patients, and included individuals who experienced massive bleeding after postoperative day 8.

Results

The incidence of bleeding was 2% among all patients. One percent of cases with bleeding occurred between postoperative days 8 and 14. None of the patients exhibited an abnormality in preoperative or postoperative coagulation tests. Mean blood loss was approximately 1 unit. In all patients, clots in the nose were cleaned, bleeding was subsequently controlled by placement of a polyvinyl alcohol sponge tampon soaked in adrenalin and tranexamic acid, and intravenous administration of 250 mg tranexamic acid in isotonic saline solution. This treatment was sufficient for all cases. None of the patients expereinced recurrent bleeding nor did they require a blood transfusion.

Conclusion

Late bleeding in septorhinoplasty is rare. It may be prevented by completely filling the nasal cavity so that there is no dead space between the septal mucosal membranes and the drainage opening. If bleeding occurs, it can be treated by placement of a tampon soaked in adrenalin and tranexamic acid plus intravenous administration of 250 mg tranexamic acid.

Retrospective Study of 122 Dogs That Were Treated with the Antifibrinolytic Drug Aminocaproic Acid: 2010-2012

Antifibrinolytic drugs are used to promote hemostasis and decrease the need for red blood cell transfusion. Medical records of 122 dogs that were prescribed either oral or intravenous aminocaproic acid between 2010 and 2012 were evaluated retrospectively. Of the 122 dogs, three experienced possible drug-related adverse effects. No significant differences were identified between dogs that experienced adverse effects and those that did not and the possible adverse effects noted were all minor. All dogs that received packed red blood cell transfusions were evaluated for correlations between baseline packed cell volume or dose of red blood cells and aminocaproic acid dose and no correlation was identified. Dogs that received aminocaproic acid as a treatment for active bleeding were divided by cause of hemorrhage into the following groups: neoplastic, non-neoplastic, and unknown. No significant differences in aminocaproic acid dose or the percentage of patients requiring a blood transfusion were identified between groups.

Antifibrinolytics (lysine analogues) for the prevention of bleeding in people with haematological disorders

BACKGROUND

People with haematological disorders are frequently at risk of severe or life-threatening bleeding as a result of thrombocytopenia (reduced platelet count). This is despite the routine use of prophylactic platelet transfusions to prevent bleeding once the platelet count falls below a certain threshold. Platelet transfusions are not without risk and adverse events may be life-threatening. A possible adjunct to prophylactic platelet transfusions is the use of antifibrinolytics, specifically the lysine analogues tranexamic acid (TXA) and epsilon aminocaproic acid (EACA). This is an update of a Cochrane review first published in 2013.

OBJECTIVES

To determine the efficacy and safety of antifibrinolytics (lysine analogues) in preventing bleeding in people with haematological disorders.

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (The Cochrane Library 2016, Issue 3), MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1937), the Transfusion Evidence Library (from 1950) and ongoing trial databases to 07 March 2016.

SELECTION CRITERIA

We included RCTs involving participants with haematological disorders, who would routinely require prophylactic platelet transfusions to prevent bleeding. We only included trials involving the use of the lysine analogues TXA and EACA.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all electronically-derived citations and abstracts of papers, identified by the review search strategy, for relevancy. Two review authors independently assessed the full text of all potentially relevant trials for eligibility, completed the data extraction and assessed the studies for risk of bias using The Cochrane Collaboration's 'Risk of bias' tool. We requested missing data from one author but the data were no longer available. The outcomes are reported narratively: we performed no meta-analyses because of the heterogeneity of the available data.

MAIN RESULTS

We identified three new studies in this update of the review. In total seven studies were eligible for inclusion, three were ongoing RCTs and four were completed studies. The four completed studies were included in the original review and the three ongoing studies were included in this update. We did not identify any RCTs that compared TXA with EACA.Of the four completed studies, one cross-over TXA study (eight participants) was excluded from the outcome analysis because it had very flawed study methodology. Data from the other three studies were all at unclear risk of bias due to lack of reporting of study methodology.Three studies (two TXA (12 to 56 participants), one EACA (18 participants) reported in four articles (published 1983 to 1995) were included in the narrative review. All three studies compared the drug with placebo. All three studies included adults with acute leukaemia receiving chemotherapy. One study (12 participants) only included participants with acute promyelocytic leukaemia. None of the studies included children. One of the three studies reported funding sources and this study was funded by a charity.We are uncertain whether antifibrinolytics reduce the risk of bleeding (three studies; 86 participants; very low-quality evidence). Only one study reported the number of bleeding events per participant and there was no difference in the number of bleeding events seen during induction or consolidation chemotherapy between TXA and placebo (induction; 38 participants; mean difference (MD) 1.70 bleeding events, 95% confidence interval (CI) -0.37 to 3.77: consolidation; 18 participants; MD -1.50 bleeding events, 95% CI -3.25 to 0.25; very low-quality evidence). The two other studies suggested bleeding was reduced in the antifibrinolytic study arm, but this was statistically significant in only one of these two studies.Two studies reported thromboembolism and no events occurred (68 participants, very low-quality evidence).All three studies reported a reduction in platelet transfusion usage (three studies, 86 participants; very low-quality evidence), but this was reported in different ways and no meta-analysis could be performed. No trials reported the number of platelet transfusions per participant. Only one study reported the number of platelet components per participant and there was a reduction in the number of platelet components per participant during consolidation chemotherapy but not during induction chemotherapy (consolidation; 18 participants; MD -5.60 platelet units, 95% CI -9.02 to -2.18: induction; 38 participants, MD -1.00 platelet units, 95% CI -9.11 to 7.11; very low-quality evidence).Only one study reported adverse events of TXA as an outcome measure and none occurred. One study stated side effects of EACA were minimal but no further information was provided (two studies, 74 participants, very low-quality evidence).None of the studies reported on the following pre-specified outcomes: overall mortality, adverse events of transfusion, disseminated intravascular coagulation (DIC) or quality of life (QoL).

AUTHORS' CONCLUSIONS

Our results indicate that the evidence available for the use of antifibrinolytics in haematology patients is very limited. The trials were too small to assess whether or not antifibrinolytics decrease bleeding. No trials reported the number of platelet transfusions per participant. The trials were too small to assess whether or not antifibrinolytics increased the risk of thromboembolic events or other adverse events. There are three ongoing RCTs (1276 participants) due to be completed in 2017 and 2020.

WITHDRAWN: Haemostatic drugs for traumatic brain injury

May 2015: The authors have asked for this review to be withdrawn. The information contained in this review has been included in the review 'Antifibrinolytic drugs for acute traumatic injury'.

The editorial group responsible for this previously published document have withdrawn it from publication.

HALT-IT--tranexamic acid for the treatment of gastrointestinal bleeding: study protocol for a randomised controlled trial

Background

Gastrointestinal bleeding is a common emergency that causes substantial mortality worldwide. Acute upper and lower gastrointestinal bleeding accounts for about 75,000 hospital admissions each year in the UK and causes the death of about 10% of these patients.

Tranexamic acid has been shown to reduce the need for blood transfusion in surgical patients and to reduce mortality in bleeding trauma patients, with no apparent increase in thromboembolic events.

A systematic review of clinical trials of upper gastrointestinal bleeding shows a reduction in the risk of death with tranexamic acid but the quality of the trials was poor and the estimates are imprecise. The trials were also too small to assess the effect of tranexamic acid on thromboembolic events.

Methods

HALT-IT is a pragmatic, randomised, double-blind, placebo-controlled trial which will determine the effect of tranexamic acid on mortality, morbidity (re-bleeding, non-fatal vascular events), blood transfusion, surgical intervention, and health status in patients with acute gastrointestinal bleeding. Eight thousand adult patients who fulfil the eligibility criteria will be randomised to receive tranexamic acid or placebo.

Adults with significant acute upper or lower gastrointestinal bleeding can be included if the responsible doctor is substantially uncertain as to whether or not to use tranexamic acid in that particular patient.

Trial treatment consists of a loading dose of tranexamic acid (1 g by intravenous injection) or placebo (sodium chloride 0.9%) given as soon as possible after randomisation, followed by an intravenous infusion of 3 g tranexamic acid or placebo (sodium chloride 0.9%) over 24 hours.

The main analyses will compare those allocated tranexamic acid with those allocated placebo, on an intention-to-treat basis. Results will be presented as effect estimates with a measure of precision (95% confidence intervals). Subgroup analyses for the primary outcome will be based on time to treatment, source of bleeding (upper versus lower), suspected variceal bleeding and severity of bleeding. A study with 8,000 patients will have over 90% power to detect a 25% reduction in mortality from 10% to 7.5%.

Trial registration

Current Controlled Trials ISRCTN11225767 (registration date: 3 July 2012); Clinicaltrials.gov NCT01658124 (registration date: 26 July 2012).

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-450) contains supplementary material, which is available to authorized users.

Comparison of topical and intravenous tranexamic acid on blood loss and transfusion rates in total hip arthroplasty

The objective of this study was to determine whether topical tranexamic acid (TXA) carried similar hemostatic effect compared with intravenous TXA in total hip arthroplasty (THA). Three hundred and three THA patients were enrolled and randomized into 3 groups: no TXA group, topical and intravenous TXA group. The results showed that the topical and intravenous TXA group had reduced but similar blood transfusion rates (5.88% v. s. 5.94%, P = 0.816). No significant difference was detected in total blood loss between the two TXA groups [(963.4 ± 421.3) ml vs. (958.5 ± 422) ml P = 0.733]. We conclude that topical use of TXA was equally effective and safe compared with intravenous TXA in reducing blood loss and transfusion rate following THA without substantial complications.

Three-dimensionally printed biological machines powered by skeletal muscle

Combining biological components, such as cells and tissues, with soft robotics can enable the fabrication of biological machines with the ability to sense, process signals, and produce force. An intuitive demonstration of a biological machine is one that can produce motion in response to controllable external signaling. Whereas cardiac cell-driven biological actuators have been demonstrated, the requirements of these machines to respond to stimuli and exhibit controlled movement merit the use of skeletal muscle, the primary generator of actuation in animals, as a contractile power source. Here, we report the development of 3D printed hydrogel "bio-bots" with an asymmetric physical design and powered by the actuation of an engineered mammalian skeletal muscle strip to result in net locomotion of the bio-bot. Geometric design and material properties of the hydrogel bio-bots were optimized using stereolithographic 3D printing, and the effect of collagen I and fibrin extracellular matrix proteins and insulin-like growth factor 1 on the force production of engineered skeletal muscle was characterized. Electrical stimulation triggered contraction of cells in the muscle strip and net locomotion of the bio-bot with a maximum velocity of ∼ 156 μm s(-1), which is over 1.5 body lengths per min. Modeling and simulation were used to understand both the effect of different design parameters on the bio-bot and the mechanism of motion. This demonstration advances the goal of realizing forward-engineered integrated cellular machines and systems, which can have a myriad array of applications in drug screening, programmable tissue engineering, drug delivery, and biomimetic machine design.

The effect of tranexamic acid on transfusion rate in primary total hip arthroplasty

Total hip arthroplasty (THA) may produce blood loss requiring allogenic blood transfusion. Recently several authors have reported success decreasing their transfusion rate with tranexamic acid (TXA). We retrospectively reviewed our last 1595 primary THA in 1494 patients looking at whether the patients received TXA via IV infusion, topical application, or neither, and the need for a blood transfusion. Infusion of TXA acid produced a statistically significant difference in transfusion rate (p<0.001) while topical TXA failed to reach statistical significance (P=0.15). The transfusion rate without TXA was 19.86%, 4.39% with TXA infusion (odds ratio=5.36), and 12.86% (odds ratio=1.67) with topical TXA.

Antifibrinolytics (lysine analogues) for the prevention of bleeding in patients with haematological disorders

BACKGROUND

Patients with haematological disorders are frequently at risk of severe or life-threatening bleeding as a result of thrombocytopenia. This is despite the routine use of prophylactic platelet transfusions (PlTx) to prevent bleeding once the platelet count falls below a certain threshold. PlTx are not without risk and adverse events may be life-threatening. A possible adjunct to prophylactic PlTxs is the use of antifibrinolytics, specifically the lysine analogues tranexamic acid (TXA) and epsilon aminocaproic acid (EACA).

OBJECTIVES

To determine the efficacy and safety of antifibrinolytics (lysine analogues) in preventing bleeding in patients with haematological disorders.

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (CENTRAL Issue 12, 2012), MEDLINE (1948 to 10 January 2013), EMBASE (1980 to 10 January 2013), CINAHL (1982 to 10 January 2013), PubMed (e-publications only) and the Transfusion Evidence Library (1980 to January 2013). We also searched several international and ongoing trial databases to 10 January 2013 and citation-tracked relevant reference lists.

SELECTION CRITERIA

RCTs involving patients with haematological disorders, who would routinely require prophylactic platelet transfusions to prevent bleeding. We only included trials involving the use of the lysine analogues TXA and EACA.

DATA COLLECTION AND ANALYSIS

Two authors independently screened all electronically derived citations and abstracts of papers, identified by the review search strategy, for relevancy. Two authors independently assessed the full text of all potentially relevant trials for eligibility, completed the data extraction and assessed the studies for risk of bias using The Cochrane Collaboration's 'Risk of bias' tool. We requested missing data from one author but the data were no longer available. The outcomes are reported narratively: we performed no meta-analyses because of the heterogeneity of the available data.

MAIN RESULTS

Of 470 articles initially identified, 436 were excluded on the basis of the title and abstract. We reviewed 34 full-text articles from which four studies reported in five articles were eligible for inclusion. We did not identify any RCTs which compared TXA with EACA. We did not identify any ongoing RCTs.One cross-over TXA study (eight patients) was excluded from the outcome analysis because data from this study were at a high risk of bias. Data from the other three studies were all at unclear risk of bias due to lack of reporting of study methodology.Three studies (two TXA (12 to 56 patients), one EACA (18 patients)) reported in four articles (published 1983 to 1995) were included in the narrative review. All three studies compared the drug with placebo.All studies reported bleeding, but it was reported in different ways. All three studies suggested antifibrinolytics reduced the risk of bleeding. The first study showed a difference in average bleeding score of 42 in placebo (P) versus three (TXA). The second study only showed a difference in bleeding episodes during consolidation chemotherapy, with a mean of 2.6 episodes/patient (standard deviation (SD) 2.2) (P) versus a mean of 1.1 episodes/patient (SD 1.4) (TXA). The third study reported bleeding on 50% of days at risk (P) versus bleeding on 31% of days at risk (EACA).Two studies (68 patients) reported thromboembolism and no events occurred.All three studies reported a reduction in PlTx usage. The first study reported a difference of 222 platelet units (P) versus 69 platelet units (TXA). The second study only showed a difference in total platelet usage during consolidation chemotherapy, with a mean of 9.3 units (SD 3.3) (P) versus 3.7 (SD 4.1) (TXA). The third study reported one PlTx every 10.5 days at risk (P) versus one PlTx every 13.3 days at risk (EACA).Two studies reported red cell transfusion requirements and one study found a reduction in red cell transfusion usage.One study reported death due to bleeding as an outcome measure and none occurred.Only one study reported adverse events of TXA as an outcome measure and none occurred.None of the studies reported on the following pre-specified outcomes: overall mortality, adverse events of transfusion, disseminated intravascular coagulation (DIC) or quality of life (QoL).

AUTHORS' CONCLUSIONS

Our results indicate that the evidence available for the use of antifibrinolytics in haematology patients is very limited. The only available data suggest that TXA and EACA may be useful adjuncts to platelet transfusions so that platelet use, and the complications associated with their use, can be reduced. However, the trials were too small to assess whether antifibrinolytics increased the risk of thromboembolic events. Large, high-quality RCTs are required before antifibrinolytics can be demonstrated to be efficacious and safe in widespread clinical practice.

Plasminogen controls inflammation and pathogenesis of influenza virus infections via fibrinolysis

Detrimental inflammation of the lungs is a hallmark of severe influenza virus infections. Endothelial cells are the source of cytokine amplification, although mechanisms underlying this process are unknown. Here, using combined pharmacological and gene-deletion approaches, we show that plasminogen controls lung inflammation and pathogenesis of infections with influenza A/PR/8/34, highly pathogenic H5N1 and 2009 pandemic H1N1 viruses. Reduction of virus replication was not responsible for the observed effect. However, pharmacological depletion of fibrinogen, the main target of plasminogen reversed disease resistance of plasminogen-deficient mice or mice treated with an inhibitor of plasminogen-mediated fibrinolysis. Therefore, plasminogen contributes to the deleterious inflammation of the lungs and local fibrin clot formation may be implicated in host defense against influenza virus infections. Our studies suggest that the hemostatic system might be explored for novel treatments against influenza.

Influenza viruses, including H5N1 bird influenza viruses continue to form a major threat for public health. Available antiviral drugs for the treatment of influenza are effective to a limited extent and the emergence of resistant viruses may further undermine their use. The symptoms associated with influenza are caused by replication of the virus in the respiratory tract and the host immune response. Here, we report that a molecule of the fibrinolytic system, plasminogen, contributes to inflammation caused by influenza. Inhibiting the action of plasminogen protected mice from severe influenza infections, including those caused by H5N1 and H1N1 pandemic 2009 viruses and may be a promising novel strategy to treat influenza.

Tranexamic acid for reduction of blood loss during total hip arthroplasty

In this study, we evaluated the hemostatic effects of tranexamic acid (TNA), an antifibrinolytic drug, by examining the timing of its administration during total hip arthroplasty. One hundred seven patients being treated for osteoarthritis of the hip joint were randomly divided into 5 groups based on the timing of TNA administration. The intraoperative blood loss, postoperative blood loss, and hemoglobin of these patients who received TNA at different times during the procedure were monitored. We found that the intraoperative blood loss in the preoperative TNA administration groups was significantly lower than both control and postoperative TNA administration groups. Furthermore, 1 g TNA 10 minutes before surgery and 6 hours after the first administration was most effective for the reduction of blood loss during total hip arthroplasty.

The blood-saving effect of tranexamic acid in minimally invasive total knee replacement

Tranexamic acid (TEA), an inhibitor of fibrinolysis, reduces blood loss after routine total knee replacement (TKR). However, controversy persists regarding the dosage and timing of administration of this drug during surgery. We performed a prospective randomised controlled study to examine the optimum blood-saving effect of TEA in minimally invasive TKR.

We randomly assigned 151 patients who underwent unilateral minimally invasive TKR to three groups: 1) a placebo group (50 patients); 2) a one-dose TEA group (52 patients), who received one injection of TEA (10 mg/kg) intra-operatively on deflation of the tourniquet; and 3) a two-dose TEA group (49 patients), who received two injections of TEA (10 mg/kg) given pre-operatively and intra-operatively. Total blood loss was calculated from the maximum loss of haemoglobin. All patients were followed clinically for the presence of venous thromboembolism (VTE).

The mean total blood loss was significantly higher in the placebo group than in the other two groups (1222 ml (845 to 2043) versus 1035 ml (397 to 1934) and 986 ml (542 to 1811), respectively (both p < 0.0001)). The mean blood loss was not significantly different between the one- and two-TEA groups (p = 0.148). The mean transfusion rate was higher in the placebo group than in the other two groups (22% versus 3.8% (p = 0.006) and 6.1% (p = 0.041), respectively) and there was no statistically significant difference in the mean transfusion rate between the one- and two-TEA groups (p = 0.672). Only one patient, in the two-dose group, had a radiologically confirmed deep venous thrombosis.

Our prospective randomised controlled study showed that one intra-operative injection of TEA is effective for blood conservation after minimally invasive TKR.

Risk of deep venous thrombosis in drain clamping with tranexamic acid and carbazochrome sodium sulfonate hydrate in total knee arthroplasty

The aim of this randomized prospective study was to clarify risks associated with a drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate after total knee arthroplasty (TKA). Subjects comprised 100 patients scheduled to undergo TKA, randomized into 2 groups: 50 patients received the drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate and 50 patients received drain-clamping with saline. Although bleeding volume was significantly lower in the group with tranexamic acid and carbazochrome sodium sulfonate hydrate, risk of asymptomatic deep venous thrombosis as detected by ultrasonography was comparable between groups. Tranexamic acid and carbazochrome sodium sulfonate hydrate in the drain-clamping method help reduce bleeding after TKA without increasing the risk of deep venous thrombosis.

The importance of early treatment with tranexamic acid in bleeding trauma patients: an exploratory analysis of the CRASH-2 randomised controlled trial

BACKGROUND

The aim of the CRASH-2 trial was to assess the effects of early administration of tranexamic acid on death, vascular occlusive events, and blood transfusion in trauma patients with significant haemorrhage. Tranexamic acid significantly reduced all-cause mortality. Because tranexamic acid is thought to exert its effect through inhibition of fibrinolysis, we undertook exploratory analyses of its effect on death due to bleeding.

METHODS

The CRASH-2 trial was undertaken in 274 hospitals in 40 countries. 20,211 adult trauma patients with, or at risk of, significant bleeding were randomly assigned within 8 h of injury to either tranexamic acid (loading dose 1 g over 10 min followed by infusion of 1 g over 8 h) or placebo. Patients were randomly assigned by selection of the lowest numbered treatment pack from a box containing eight numbered packs that were identical apart from the pack number. Both participants and study staff (site investigators and trial coordinating centre staff ) were masked to treatment allocation. We examined the effect of tranexamic acid on death due to bleeding according to time to treatment, severity of haemorrhage as assessed by systolic blood pressure, Glasgow coma score (GCS), and type of injury. All analyses were by intention to treat. The trial is registered as ISRCTN86750102, ClinicalTrials.gov NCT00375258, and South African Clinical Trial Register/Department of Health DOH-27-0607-1919.

FINDINGS

10,096 patients were allocated to tranexamic acid and 10,115 to placebo, of whom 10,060 and 10,067, respectively, were analysed. 1063 deaths (35%) were due to bleeding. We recorded strong evidence that the effect of tranexamic acid on death due to bleeding varied according to the time from injury to treatment (test for interaction p<0.0001). Early treatment (≤1 h from injury) significantly reduced the risk of death due to bleeding (198/3747 [5.3%] events in tranexamic acid group vs 286/3704 [7.7%] in placebo group; relative risk [RR] 0.68, 95% CI 0.57-0.82; p<0.0001). Treatment given between 1 and 3 h also reduced the risk of death due to bleeding (147/3037 [4.8%] vs 184/2996 [6.1%]; RR 0.79, 0.64-0.97; p=0.03). Treatment given after 3 h seemed to increase the risk of death due to bleeding (144/3272 [4.4%] vs 103/3362 [3.1%]; RR 1.44, 1.12-1.84; p=0.004). We recorded no evidence that the effect of tranexamic acid on death due to bleeding varied by systolic blood pressure, Glasgow coma score, or type of injury.

INTERPRETATION

Tranexamic acid should be given as early as possible to bleeding trauma patients. For trauma patients admitted late after injury, tranexamic acid is less effective and could be harmful.

FUNDING

UK NIHR Health Technology Assessment programme, Pfizer, BUPA Foundation, and J P Moulton Charitable Foundation.

Mesenchymal stem cells from adipose and bone marrow promote angiogenesis via distinct cytokine and protease expression mechanisms

Using a fibrin-based angiogenesis model, we have established that there is no canonical mechanism used by endothelial cells (ECs) to degrade the surrounding extracellular matrix (ECM), but rather the set of proteases used is dependent on the mural cells providing the angiogenic cues. Mesenchymal stem cells (MSCs) originating from different tissues, which are thought to be phenotypically similar, promote angiogenesis through distinct mechanisms. Specifically, adipose-derived stem cells (ASCs) promote utilization of the plasminogen activator-plasmin axis by ECs as the primary means of vessel invasion and elongation in fibrin. Matrix metalloproteinases (MMPs) serve a purpose in regulating capillary diameter and possibly in stabilizing the nascent vessels. These proteolytic mechanisms are more akin to those involved in fibroblast-mediated angiogenesis than to those in bone marrow-derived stem cell (BMSC)-mediated angiogenesis. In addition, expression patterns of angiogenic factors such as urokinase plasminogen activator (uPA), hepatocyte growth factor (HGF), and tumor necrosis factor alpha (TNFα) were similar for ASC and fibroblast-mediated angiogenesis, and in direct contrast to BMSC-mediated angiogenesis. The present study illustrates that the nature of the heterotypic interactions between mural cells and endothelial cells depend on the identity of the mural cell used. Even MSCs which are shown to behave phenotypically similar do not stimulate angiogenesis via the same mechanisms.

The WOMAN Trial (World Maternal Antifibrinolytic Trial): tranexamic acid for the treatment of postpartum haemorrhage: an international randomised, double blind placebo controlled trial

BACKGROUND

Each year, worldwide about 530,000 women die from causes related to pregnancy and childbirth. Of the deaths 99% are in low and middle income countries. Obstetric haemorrhage is the leading cause of maternal mortality, most occurring in the postpartum period. Systemic antifibrinolytic agents are widely used in surgery to prevent clot breakdown (fibrinolysis) in order to reduce surgical blood loss. At present there is little reliable evidence from randomised trials on the effectiveness of tranexamic acid in the treatment of postpartum haemorrhage.

METHODS

The Trial aims to determine the effect of early administration of tranexamic acid on mortality, hysterectomy and other morbidities (surgical interventions, blood transfusion, risk of non-fatal vascular events) in women with clinically diagnosed postpartum haemorrhage. The use of health services and safety, especially thromboembolic effect, on breastfed babies will also be assessed. The trial will be a large, pragmatic, randomised, double blind, placebo controlled trial among 15,000 women with a clinical diagnosis of postpartum haemorrhage. All legally adult women with clinically diagnosed postpartum haemorrhage following vaginal delivery of a baby or caesarean section will potentially be eligible. The fundamental eligibility criterion is the responsible clinician's 'uncertainty' as to whether or not to use an antifibrinolytic agent in a particular woman with postpartum haemorrhage. Treatment will entail a dose of tranexamic acid (1 gram by intravenous injection) or placebo (sodium chloride 0.9%) will be given as soon as possible after randomisation. A second dose may be given if after 30 minutes bleeding continues, or if it stops and restarts within 24 hours after the first dose. The main analyses will be on an 'intention to treat' basis, irrespective of whether the allocated treatment was received or not. Subgroup analyses for the primary outcome will be based on type of delivery; administration or not of prophylactic uterotonics; and on whether the clinical decision to consider trial entry was based primarily on estimated blood loss alone or on haemodynamic instability. A study with 15,000 women will have over 90% power to detect a 25% reduction from 4% to 3% in the primary endpoint of mortality or hysterectomy.

Haemostatic drugs for traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of death and disability. Intracranial bleeding is a common complication of TBI, and intracranial bleeding can develop or worsen after hospital admission. Haemostatic drugs may reduce the occurrence or size of intracranial bleeds and consequently lower the morbidity and mortality associated with TBI.

OBJECTIVES

To assess the effects of haemostatic drugs on mortality, disability and thrombotic complications in patients with traumatic brain injury.

SEARCH STRATEGY

We searched the electronic databases: Cochrane Injuries Group Specialised Register (3 February 2009), CENTRAL (The Cochrane Library 2009, Issue 1), MEDLINE (1950 to Week 3 2009), PubMed (searched 3 February 2009 (last 180 days)), EMBASE (1980 to Week 4 2009), CINAHL (1982 to January 2009), ISI Web of Science: Science Citation Index Expanded (SCI-EXPANDED) (1970 to January 2009), ISI Web of Science: Conference Proceedings Citation Index - Science (CPCI-S) (1990 to January 2009).

SELECTION CRITERIA

We included published and unpublished randomised controlled trials comparing haemostatic drugs (antifibrinolytics: aprotinin, tranexamic acid (TXA), aminocaproic acid or recombined activated factor VIIa (rFVIIa)) with placebo, no treatment, or other treatment in patients with acute traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two review authors independently examined all electronic records, and extracted the data. We judged that there was clinical heterogeneity between trials so we did not attempt to pool the results of the included trials. The results are reported separately.

MAIN RESULTS

We included two trials. One was a post-hoc analysis of 30 TBI patients from a randomised controlled trial of rFVIIa in blunt trauma patients. The risk ratio for mortality at 30 days was 0.64 (95% CI 0.25 to 1.63) for rFVIIa compared to placebo. This result should be considered with caution as the subgroup analysis was not pre-specified for the trial. The other trial evaluated the effect of rFVIIa in 97 TBI patients with evidence of intracerebral bleeding in a computed tomography (CT) scan. The corresponding risk ratio for mortality at the last follow up was 1.08 (95% CI 0.44 to 2.68). The quality of the reporting of both trials was poor so it was difficult to assess the risk of bias.

AUTHORS' CONCLUSIONS

There is no reliable evidence from randomised controlled trials to support the effectiveness of haemostatic drugs in reducing mortality or disability in patients with TBI. New randomised controlled trials assessing the effects of haemostatic drugs in TBI patients should be conducted. These trials should be large enough to detect clinically plausible treatment effects.

The effect of tranexamic acid on reducing blood loss in cementless total hip arthroplasty under epidural anesthesia

Total hip arthroplasty (THA) is associated with high intraoperative and postoperative blood loss. Antifibrinolytic drugs have been used to minimize the potential risks of bleeding and blood transfusion. Studies on the effect of tranexamic acid on decreasing blood loss in THA have revealed interesting results, but most have focused on cemented THA. Yet its benefits in THA, especially in cementless THA, have not been proved. We conducted a prospective double-blind randomized controlled study on 64 patients who were candidates for cementless THA under epidural anesthesia between 2006 and 2008. Patients were randomly assigned into study and control groups. Patients in both groups were well matched regarding preoperative characteristics. Five minutes preoperatively 32 patients of the study and control groups received 15 mg/kg tranexamic acid or normal saline intravenously respectively. Our findings showed a significantly smaller decrease in 6- and 24-hour postoperative hemoglobin levels, less intraoperative and postoperative bleeding, and less need for allogenic blood transfusion in the tranexamic acid group. Our results also revealed a higher mean of 6- and 24-hour hematocrit level and shorter hospital stay in the tranexamic acid group compared to the control group, which were not statistically meaningful. In our study no thromboembolic event was seen; except 1 patient in the control group. Our study showed that administering tranexamic acid before the start of cementless THA under epidural anesthesia can reduce intraoperative and postoperative bleeding as well as need for blood transfusion.

Epsilon-aminocaproic acid is a useful fibrin degradation inhibitor for cartilage tissue engineering

Fibrin is a hydrogel carrier widely used in cartilage tissue engineering. It is rapidly degraded by plasmin, which is produced by the cells. epsilon-Aminocaproic acid (EACA) can be used to inhibit this enzyme and thus save the fibrin carrier. In this study we investigated the effect of EACA on the transforming growth factor beta-1-induced chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs). To assess this, we used the standard pellet culture system, and EACA treatment was compared to an untreated chondrogenic control. To investigate differentiation, real-time RT-PCR was used on chondrocytic marker genes: aggrecan, collagen types II and X, and the SRY-related HMG-box gene 9 (SOX9). Also, specific glycosaminoglycan production was measured. Safranin-O/fast green staining was used to localize proteoglycans and collagens within the pellet. All results concur that EACA did not affect the chondrogenic differentiation process at 5 muM concentration, which is adequate to inhibit fibrin degradation. Therefore, it is a useful plasmin inhibitor for cartilage tissue engineering with hMSCs.

Efficacy and safety of prophylactic large dose of tranexamic acid in spine surgery: a prospective, randomized, double-blind, placebo-controlled study

STUDY DESIGN

This is a double blind randomized placebo controlled study, after obtaining approval of ethics committee in the hospital and informed written consent, 64 patients were randomized equally into 2 groups (tranexamic acid (TA) and placebo).

OBJECTIVE

To evaluate efficacy and safety of large doses of TA on blood loss during spinal operations.

SUMMARY OF BACKGROUND DATA

Blood loss associated with spinal operations is a common potential cause of morbidity and often requires blood transfusion which subject patients to the known risks of blood transfusion including transmission of diseases. TA is used routinely to reduce bleeding in cardiac, orthopaedic, and hepatic surgery, however, its use in neurosurgery is uncommon and only few studies reported the use of antifibrinolytic drugs in spine surgery.

METHODS

Sixty-four consecutive patients undergoing spinal surgery with expected significant blood loss at King Khalid University Hospital between June 2005 and December 2006 were randomly assigned to 2 groups, TA and placebo. Shortly after the induction of anesthesia, patients received either TA or placebo as a loading dose of 2 g (for adults) or 30 mg/kg (for children), followed immediately by continuous infusion of 100 mg/h (for adults) or 1 mg/kg/h (for children) during surgery and for 5 hours after the operation. Outcome measures included total (i.e., intraoperative and postoperative) blood loss, amount of blood transfusion, as well as postoperative hemoglobin, and hematocrite levels. The data were analyzed by means of Statistical Package for the Social Science Version 12.0. The results were presented as mean +/- SD. Independent Student t test was used to compare the 2 groups and differences were considered significant if the P-value was <0.05.

RESULTS

There were 39 males and 25 females, ranging in age from 4 to 86 years with a mean of 51 and median of 56 years. Eighteen patients had multilevel anterior cervical discectomies with or without internal fixation, 22 patients had decompressive surgery (12 laminectomies and 10 intersegmental decompressions) for multiseg- ment spinal stenosis, 15 patients had laminectomy with posterior spinal fixation, and remaining 9 patients had laminectomy and excision of spinal tumor. Statistical analysis showed no significant differences between the 2 study groups with regard to age, sex, weight, preoperative hemoglobin, and hematocrite levels, type of surgery, as well as operative time. In contrast, patients who received TA had 49% reduction of blood loss (P < 0.007) and required 80% less blood transfusion (P < 0.008) than patients who received placebo. The hospital stay was shorter in the TA group, but it did not achieve statistical significance. There were no complications related to the use of large doses of TA in this study.

CONCLUSIONS

Prophylactic use of large doses of TA provides an effective, safe, and cheap method for reducing blood loss during and after spinal operations. Hence, TAmay help in reducing not only transfusion related complications but also operative expenses. Considering the limited number of patients in this study, our results need, however, to be validated on a larger number of patients, probably in a multicenter study.

Plasminogen potentiates thrombin cytotoxicity and contributes to pathology of intracerebral hemorrhage in rats

Thrombin and plasmin are serine proteases involved in blood coagulation and fibrinolysis, whose precursors are circulating in blood stream. These blood-derived proteases might play important roles in the pathogenesis of intracerebral hemorrhage by acting on brain parenchymal cells. We previously reported that thrombin induced delayed neuronal injury through extracellular signal-regulated kinase (ERK)-dependent pathways. Here, we investigated potential cytotoxic actions of plasminogen, a precursor protein of plasmin, using slice cultures prepared from neonatal rat brain and intracortical microinjection model in adult rats. Although plasminogen alone did not evoke prominent neuronal injury, plasminogen caused significant neuronal injury when combined with a moderate concentration of thrombin (30 U/mL) in the cerebral cortex of slice cultures. The cortical injury was prevented by tranexamic acid and aprotinin. The combined neurotoxicity of thrombin and plasminogen was also prevented by PD98059, an inhibitor of ERK pathway, as well as by other agents that have been shown to prevent cortical injury induced by a higher concentration (100 U/mL) of thrombin alone. Extracellular signal-regulated kinase phosphorylation after plasminogen exposure was localized in cortical astrocytes. Moreover, microinjection of plasminogen in vivo potentiated thrombin-induced cortical injury, and inhibition of plasmin ameliorated hemorrhage-induced neuronal loss in the cerebral cortex. These results suggest that plasminogen/plasmin system augmenting thrombin neurotoxicity participates in hemorrhagic cortical injury.

Effect of plasmin, plasminogen activators and a plasmin inhibitor on bovine in vitro embryo production

In the present study, four experiments were conducted to investigate the possible effects of plasminogen activators (urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA)), plasmin, and a plasmin inhibitor (epsilon-aminocaproic acid (ϵ-ACA)) on different stages of bovine in vitro embryo production (IVP). The concentrations of these modifiers in IVP media were conditioned according to the plasminogen activator activity of bovine preovulatory follicular fluid. Media were modified in a single phase of IVP with an 18 h or 24 h incubation for in vitro maturation (IVM) and a 24 h or 48 h incubation for the IVF or in vitro culture (IVC), respectively. After IVM the oocytes were either fixed and stained or underwent IVF and IVC. The main findings were: (1) plasmin added to the 18 h IVM medium increased maturation rate without affecting fertilisation or embryo development rates; (2) t-PA added to the IVF medium significantly increased cleavage; (3) u-PA added to the IVC medium significantly increased embryo development rates; (4) the efficiency of all phases of IVP was reduced after the addition of ϵ-ACA; and (5) plasminogen addition had no effect in any IVP phase tested. We conclude that the members of the plasminogen activator–plasmin system contribute in different ways to bovine IVM, IVF and IVC.

Antifibrinolytic use in adult cardiac surgery

PURPOSE OF REVIEW

Antifibrinolytics are used to attenuate the coagulopathy associated with cardiopulmonary bypass. However, recent studies suggest that the antifibrinolytic aprotinin is associated with increased renal and vascular events and death compared to its alternatives. To develop a recommendation for antifibrinolytic use in adult cardiac surgery, we performed a systematic review and meta-analysis to determine the association of the antifibrinolytics with efficacy, safety and cost outcomes.

RECENT FINDINGS

Aprotinin, when compared to placebo, significantly decreased blood transfusions and reoperations for bleeding, strokes and cognitive dysfunction, and significantly increased renal dysfunction but not renal failure. Tranexamic acid significantly decreased blood transfusions, but was not statistically associated with other outcomes. Aminocaproic acid was not statistically associated with any measured outcome. Although aprotinin costs more than its alternatives, its costs may approximate those of its alternatives when longer time horizons are considered.

SUMMARY

We support the targeted use of aprotinin in adult cardiac surgery patients at high risk for bleeding or stroke, and discourage the use of aprotinin in those at high risk for renal failure. Although fewer data are available for tranexamic and aminocaproic acid, we support their use as alternatives to aprotinin in those at high risk for bleeding.

Antifibrinolytic additives to fibrin glue for laparoscopic wound closure in urinary tract

BACKGROUND AND OBJECTIVES

Fibrinolytic activity of urine may rapidly degrade fibrin glue used in the urinary tract, thereby limiting tissue adhesion. The goals of this study were to verify the ability of antifibrinolytic agents to delay the degradation of fibrin glue in the urinary tract and to assess the results of this delay on subsequent wound healing.

MATERIALS AND METHODS

In 25 domestic pigs, a 3.5-cm incision in the urinary bladder was left open (N = 6) or closed laparoscopically with fibrin glue alone (N = 6), fibrin glue containing aprotinin 5000 KIU/mL (N = 6), or fibrin glue containing aprotinin 2500 KIU/mL with (N = 4) or without (N = 3) aminocaproic acid 12.5 mg/mL. At harvest 7 days later, the bladder was tested for leakage. Histologic features were scored by a pathologist blinded to the closure method.

RESULTS

There were no significant differences among the groups in the amount of leakage at harvest. Significant fibrin glue material in the wound was noted more often in the pigs treated with fibrin glue plus aprotinin (7 of 13) than in the fibrin glue-only group (0 of 6; P = 0.04). The presence of significant fibrin material in the wound correlated well with absence of granulation tissue (P < 0.001), such that granulation tissue bridging the wound edges was found more often in the fibrin glue-only group (6 of 6) than in the groups treated with fibrin glue plus aprotinin (4 of 13; P = 0.01).

CONCLUSIONS

Although aprotinin +/- aminocaproic acid did delay the degradation of fibrin glue used to close a bladder wound, it was associated with inhibition of granulation tissue in the glued wound. These findings suggest that aprotinin alone and aprotinin plus aminocaproic acid are not useful additives to fibrin glue used for wound closure in the urinary tract.

Inhibitors for the in vitro assembly of Lp(a)

Lp(a) is composed of an LDL-like core and the glycoprotein apo(a). Current evidence strongly suggests that the assembly of this atherogenic lipoprotein proceeds outside the liver cells in a two-step fashion. In the first step, a loose complex is formed involving kringle-4 motifs in apo(a) and one or more Lys side chains in apoB-100. In the second step, this complex is stabilized by a disulfide bridge. Indications are that Lp(a) assembly is critical in the determination of plasma apo(a) concentrations. Therefore, we searched for substances that interfere with the first step of Lp(a) assembly. epsilon-Aminohexoic acid (epsilon-AHA), known as an inhibitor from earlier assembly studies, had an IC50 of 4.8 mmol/L. The IC50 of Pro, HO-p-aminobenzene sulfonamide, Lys, N-epsilon-acetyl-Lys, taurine, Glu, serotonin, and benzamidine were all > 20 mmol/L. gamma-Aminobutyric acid, spermine, and spermidine exhibited IC50 on the same order of magnitude as epsilon-AHA. The substances with the highest inhibitory action were tranexamic acid and delta-aminovaleric acid. Seven of eight patients treated in a pilot study with tranexamic acid (Cyclocapron) responded with a decrease of plasma apo(a) of 18.5 +/- 8.2%. We suggest that substances that interfere with the Lp(a) assembly are worth pursuing further for their usefulness as therapeutic agents in reducing high plasma Lp(a) concentrations.

Role of endogenous platelet-derived growth factor in arterial smooth muscle cell migration after balloon catheter injury

The process of intimal thickening after de-endothelializing injury to the rat carotid artery is dependent on the migration of smooth muscle cells from the media. Recent reports have suggested that platelet-derived growth factor may be an important mediator of migration after injury. We have addressed this issue by directly determining smooth muscle cell migration in injured arteries of animals depleted of platelets and after administration of an antibody that blocks platelet-derived growth factor. Because there is a reported association between plasminogen activator synthesis and smooth muscle cell migration, we assayed the activity levels of plasminogen activators after arterial injury and also assessed the effect of a plasmin inhibitor on migration. The data suggest that platelet-derived growth factor, released by platelets at sites of arterial injury, is an endogenous mediator of smooth muscle cell migration; that plasmin generation, catalyzed by tissue-type plasminogen activator, is necessary for migration; and that one way in which platelet-derived growth factor may act is by stimulation of the synthesis of tissue-type plasminogen activator by smooth muscle cells.

The role of plasminogen activation in smooth muscle cell migration after arterial injury

The migration of smooth muscle cells from the media to the intima that occurs after balloon catheter injury to the rat common carotid artery has been quantified by an electron microscopic surveying technique. These vessels have also been assayed for plasminogen-activator activity, which was found to rise sharply 4 days after balloon injury. At this time point smooth muscle cells begin to migrate in appreciable numbers. In order to investigate whether there is a causal relationship between plasminogen-activator activity and smooth muscle cell migration, animals were dosed with tranexamic acid. This synthetic inhibitor of plasmin activity reduced smooth muscle cell migration by 73% (p < 0.05), indicating that plasmin activity is necessary for migration after balloon injury. Lisinopril, an inhibitor of angiotensin-converting enzyme, inhibited smooth muscle cell migration after balloon injury by 78% (p < 0.01) but did not influence plasminogen-activator activity. Taken together, these results show that plasmin is a necessary but not sufficient component in the pathway that leads to smooth muscle cell migration after balloon catheter injury in the rat.

Intracerebral haemorrhage after thrombolytic therapy for acute myocardial infarction

Seven cases of intracerebral haemorrhage were identified following the use of thrombolytic therapy in a total of 710 patients with acute myocardial infarction. Each case was reviewed in detail with particular attention to the presenting symptoms. A confusional state was the commonest initial feature. Increased age and male sex were associated with increased risk of cerebral bleed. The possible role of intravenous heparin in increasing risk and the management of affected cases is discussed. Early recognition and action is emphasized.

Pepsin fibrinolysis of artificial clots made from fibrinogen concentrate and bovine thrombin: the effect of pH and epsilon aminocaproic acid

Artificial clots made from fibrin glue with and without an inhibitor of fibrinolysis can be used to treat gastrointestinal bleeding. We have been unable to find descriptions of the effects of acid and pepsin upon such artificial clots. Therefore, 10(-2) mol/l epsilon aminocaproic acid was added to fibrin glue in vitro at acid concentrations of pH 1.0 and pH 5.5. Pepsin was added at 9000 U/50 ml, the expected value for fasting human subjects. There was a highly significant reduction in clot survival at pH 1.0. At pH 5.5, clot weight was also significantly decreased with pepsin, compared to control. Thus pepsin and acidity greatly affect survival of artificial clots, but the addition of epsilon aminocaproic acid did not affect clot survival.

Epsilon aminocaproic acid and the control of post-prostatectomy bleeding: a prospective double-blind study

We randomized 61 patients undergoing transurethral resection of the prostate in a double-blind parallel fashion to receive epsilon aminocaproic acid or an equivalent volume of placebo solution immediately after the operation. All blood loss during the first 72 hours postoperatively was monitored. Four patients were nonevaluable . The use of epsilon aminocaproic acid caused no significant complication or side effect. There was no significant difference in regard to blood loss, hospital stay or days on catheter drainage between the 2 groups. We conclude that the routine use of epsilon aminocaproic acid after transurethral resection of the prostate is not warranted.

The fibrinolytic system in man

The existence of a system in the human body capable of inducing the dissolution of endogenous pathologically formed thrombi was appreciated in ancient times. Considered in detail in this article are the data that have elucidated the physiologic regulation of which plasmin formation is dependent on, the plasma concentration of plasminogen, availability of activators of plasminogen in the plasma and surrounding tissue environment, the concentration of naturally present inhibitors, and the existence of fibrin in the circulation. Important in this rapidly progressive scientific discipline is consideration of the factors which control the synthesis of the components of this proteolytic enzyme system. Recently abundant information has indicated that this plasminogen-plasmin proteolytic enzyme system can be utilized therapeutically. Knowledge of the mechanisms of this system has permitted identification of agents that can be exogenously administered to releave thrombotic obstruction to blood flow in the venous (pulmonary emboli, deep vein thrombosis) and arterial (peripheral and central vessels) circulatory systems. Particularly important is the demonstration that thrombolytic agents can directly attack and alleviate the immediate cause of acute myocardial infarction. As a result of the innovations in the present decade, it is evident that the plasminogen system can be advantageously employed to reverse the pathologic effects of all thrombotic diseases.