Antifibrinolytic Therapy in Surgery for Congenital Heart Disease

A Retrospective Comparative Analysis on the Effect of Tranexamic Acid to Reduce Perioperative Blood Loss in Patients Undergoing Cervical Spine Surgery

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

The purpose of this study is to assess the impact of intravenous TXA on blood loss outcomes in anterior, posterior, and combined approaches for elective cervical spine surgery.

SUMMARY OF BACKGROUND DATA

Tranexamic acid (TXA) has been shown to reduce blood loss in a variety of operations, such as lumbar spine surgery. However, limited studies have evaluated the efficacy of TXA in cervical spine surgery.

METHODS

We performed a retrospective review of a single surgeon's elective cervical spine operations between September 2011 and March 2017. Patients were divided into 3 groups: anterior approach, posterior approach, or combined approach. Patients were then further subdivided into TXA versus control groups based on whether they received TXA treatment. We performed multiple linear regressions to assess the relationship between the use of TXA and other dependent variables (number of vertebral levels treated, need for a vertebral corpectomy) on total perioperative blood loss, intraoperative estimated blood loss, postoperative drain output, total operative time, postoperative change in hemoglobin, and occurrence of transfusion and/or postoperative deep venous thrombus (DVT).

RESULTS

We found that the use of TXA statistically significantly reduced total perioperative blood loss (P=0.04) and postoperative drain output (P=0.004) in posterior surgical approach cervical spine surgery but did not statistically significantly impact any blood loss variables in anterior or combined surgical approaches to elective cervical spine surgery. The use of TXA was a significant predictor for a decrease in intraoperative (P=0.02) and postoperative (P<0.01) blood loss.

CONCLUSIONS

This study found that TXA statistically significantly decreased total blood loss and postoperative drain output when controlling for multiple confounding factors.

LEVEL OF EVIDENCE

Level III.

Antifibrinolytic Drugs for the Prevention of Bleeding in Pediatric Cardiac Surgery on Cardiopulmonary Bypass: A Systematic Review and Meta-analysis

BACKGROUND

Bleeding is one of the commonest complications affecting children undergoing cardiac surgery on cardiopulmonary bypass. Antifibrinolytic drugs are part of a multifaceted approach aimed at reducing bleeding, though sufficiently sized pediatric studies are sparse, and dosing algorithms are heterogeneous. Our objective was to evaluate the efficacy and safety of antifibrinolytic agents as well as the effectiveness of different dosing regimens in pediatric cardiac surgery using cardiopulmonary bypass.

METHODS

We performed a systematic review and meta-analysis evaluating randomized controlled trials published between 1980 and 2019, identified by searching the databases MEDLINE, EMBASE, PubMed, and CENTRAL. All studies investigating patients <18 years of age without underlying hematological disorders were included. The primary outcome was postoperative bleeding; secondary end points included blood product transfusion, mortality, and safety (thromboses, anaphylaxis, renal or neurological dysfunction, and seizures). Different dosing regimens were compared. Studies were dual appraised, outcomes were reported descriptively and, if appropriate, quantitatively using the Review Manager 5 (REVMAN 5) software (The Cochrane Collaboration).

RESULTS

Thirty of 209 articles were included, evaluating the following drugs versus control: aprotinin n = 14, tranexamic acid (TXA) n = 12, and epsilon-aminocaproic acid (EACA) n = 4. The number of participants per intervention group ranged from 11 to 100 (median, 25; interquartile range [IQR], 20.5) with a wide age span (mean, 13 days to 5.8 years) and weight range (mean, 3.1-26.3 kg). Methodological quality was low to moderate.All agents reduced mean 24-hour blood loss compared to control: aprotinin by 6.0 mL/kg (95% confidence interval [CI], -9.1 to -3.0; P = .0001), TXA by 9.0 mL/kg (95% CI, -11.3 to -6.8; P < .00001), and EACA by 10.5 mL/kg (95% CI, -21.1 to 0.0; P = .05). Heterogeneity was low for TXA (I2 = 29%; P = .19), moderate for aprotinin (I2 = 41%; P = .11), and high for EACA (I2 = 95%; P = <.00001). All agents also reduced 24-hour blood product transfusion. There was no clear dose-response effect for TXA nor aprotinin. Studies were underpowered to detect significant differences in mortality, thromboses, anaphylaxis, and renal or neurological dysfunction.

CONCLUSIONS

The available data demonstrate efficacy for all 3 antifibrinolytic drugs. Therefore, the agent with the most favorable safety profile should be used. As sufficient data are lacking, large comparative trials are warranted to assess the relative safety and appropriate dosing regimens in pediatrics.

Intravenous Tranexamic Acid is Associated With a Clinically Significant Reduction in Blood Loss in Craniosynostosis Surgery

ABSTRACT

Blood loss is a potential cause of morbidity and mortality in craniosynostosis surgery. Recent reports have suggested that the use of tranexamic acid (TXA), an antifibrinolytic agent, mitigates this blood loss. A retrospective cohort study of patients undergoing craniosynostosis surgery at a tertiary craniofacial hospital in Sydney was undertaken. Primary outcomes were blood loss and transfusion requirements. Two groups were compared: those who received intravenous prophylactic TXA and those who underwent surgery without TXA. Statistical analysis was performed with Student t test and the Mann-Whitney U test for nonparametric results. We identified 206 patients who underwent craniosynostosis surgery over an 8 year period; 78 control patients and 128 patients that received TXA. Tranexamic acid was found to result in a weight-adjusted calculated blood loss mean difference of 9.6 ml/kg across all procedures (P = 0.0332 95% confidence interval 0.7734-18.4266). The actual blood loss reduction achieved with TXA was 6.7 ml/kg in spring cranioplasties, compared to 15.2 ml/kg in fronto-orbital remodeling procedures. There was a statistically and clinically significant reduction in postoperative transfusion incidence, with transfusions required in 27% of controls and 6% of TXA patients (P < 0.0001). The number needed to treat to prevent giving a unit of blood postoperatively was 4.8. There wxere no incidences of TXA-specific complications. This study found that TXA is a safe and effective method of decreasing blood loss and transfusion requirements in patients undergoing craniosynostosis surgery. The clinical benefit of TXA is particularly evident in the more invasive craniosynostosis surgeries.

Tranexamic Acid in Craniosynostosis Surgery: A Systematic Review and Meta-Analysis

ABSTRACT

Blood loss is a potential cause of morbidity and mortality in craniosynostosis surgery. Recent reports have suggested that the use of tranexamic acid (TXA), an antifibrinolytic agent, mitigates this blood loss. A comprehensive systematic review and subsequent meta-analysis was undertaken, with the view to clarify the effectiveness of TXA in reducing blood loss and transfusion requirements in craniosynostosis surgery. Medline and PubMed databases were searched using the preferred reporting items for systematic reviews and meta-analyses technique, and 7003 articles were assessed based on predefined selection criteria. Seven trials were identified, of which 2 were randomized controlled trials and the remainder retrospective cohort studies. All trials were assessed using the Jadad and strengthening the reporting of observational studies in epidemiology scores. The meta-analysis found a clear statistical reduction in blood loss in those patients who received TXA perioperatively, with a combined blood loss reduction of 7.06 ml/kg (95% confidence interval -8.97 to -5.15, P < 0.00001). The blood loss reduction was found to extrapolate to a reduction in perioperative transfusion requirements by 8.47 ml/kg in this cohort (95% confidence interval -10.9 to -6.04, P < 00001). There were no TXA-related adverse outcomes recorded in the 258 patients who received TXA across all trials. The trials included in this meta-analysis were limited by underpowered population sizes and significant heterogeneity in blood loss recording techniques. Further, there was significant heterogeneity amongst operations performed. The current literature appears to support the use of TXA in craniosynostosis surgery, but further high quality randomized controlled trials are indicated, ideally including a subgroup analysis between the operations performed.

Topical versus low-dose systemic tranexamic acid in pediatric cardiac surgery: A randomized clinical study

OBJECTIVES

The current study aimed to compare the benefits of topical and low-dose systemic tranexamic acid administration in pediatric cardiac surgery.

METHODS

A total of 117 children undergoing cardiac surgery for congenital heart disease were assigned into three groups. Patients in the systemic group received 20 mg/kg^-1 tranexamic acid through the cardiopulmonary bypass followed by another dose of 20 mg/kg^-1 after cardiopulmonary bypass separation. Patients in the topical group were administered with 50 mg/kg^-1 tranexamic acid poured into the pericardium, while the control group received no antifibrinolytics. The outcome measures of bleeding and blood products transfusion were recorded over the first 48 h postoperatively.

RESULTS

Chest tube drainage was significantly lower in both topical and systemic groups than the control group, but it did not differ between the case groups. Blood products requirement did not show a difference between groups. Neurological or thromboembolic events did not variate among the groups, and no deaths occurred in this study.

CONCLUSION

Topical or systemic tranexamic acid administration reduced postoperative blood loss effectively without adding an extra risk.

Biochemical properties of a Pseudomonas aminotransferase involved in caprolactam metabolism

The biodegradation of the nylon-6 precursor caprolactam by a strain of Pseudomonas jessenii proceeds via ATP-dependent hydrolytic ring opening to 6-aminohexanoate. This non-natural ω-amino acid is converted to 6-oxohexanoic acid by an aminotransferase (PjAT) belonging to the fold type I pyridoxal 5'-phosphate (PLP) enzymes. To understand the structural basis of 6-aminohexanoatate conversion, we solved different crystal structures and determined the substrate scope with a range of aliphatic and aromatic amines. Comparison with the homologous aminotransferases from Chromobacterium violaceum (CvAT) and Vibrio fluvialis (VfAT) showed that the PjAT enzyme has the lowest K_M values (highest affinity) and highest specificity constant (k_cat /K_M ) with the caprolactam degradation intermediates 6-aminohexanoate and 6-oxohexanoic acid, in accordance with its proposed in vivo function. Five distinct three-dimensional structures of PjAT were solved by protein crystallography. The structure of the aldimine intermediate formed from 6-aminohexanoate and the PLP cofactor revealed the presence of a narrow hydrophobic substrate-binding tunnel leading to the cofactor and covered by a flexible arginine, which explains the high activity and selectivity of the PjAT with 6-aminohexanoate. The results suggest that the degradation pathway for caprolactam has recruited an aminotransferase that is well adapted to 6-aminohexanoate degradation. DATABASE: The atomic coordinates and structure factors P. jessenii 6-aminohexanoate aminotransferase have been deposited in the PDB as entries 6G4B (E∙succinate complex), 6G4C (E∙phosphate complex), 6G4D (E∙PLP complex), 6G4E (E∙PLP-6-aminohexanoate intermediate), and 6G4F (E∙PMP complex).

Use of antifibrinolytics in pediatric cardiac surgery: Where are we now?

Fibrinolytic activation is a major and preventable source of bleeding in neonates and children undergoing cardiac surgery with cardiopulmonary bypass. Based on the existing literature (adult and pediatric; cardiac and noncardiac), prophylactic administration of antifibrinolytic agents can help reduce fibrinolytic activation, and consequently reduces perioperative bleeding and the requirement for blood product transfusion. Due to the increased risk of renal failure and mortality reported in adults undergoing cardiac surgery, aprotinin should not be considered as a safe option in neonates and children. Further well-designed studies would be required before the prophylactic administration of aprotinin could be considered in pediatric cardiac surgery. The lysine analogs, tranexamic acid and ϵ-aminocaproic acid,, should be considered as safe and effective antifibrinolytic agents. Although no major side effects have been reported following the administration of lysine analogs in children undergoing cardiac surgery, high-dose tranexamic acid should not be recommended in order to avoid the increased risk of clinical seizures. Despite the recent advances made in our understanding of the pharmacokinetics of tranexamic acid and ϵ-aminocaproic acid,, the optimal plasmatic concentration to be targeted remains unknown. Further studies are therefore urgently needed to better define the optimal dose regimen to be used in neonates and children. In the meantime, the dose regimen published in the most recent pharmacokinetic studies can be used. Although no studies have assessed the effect of massive bleeding and transfusion on the plasmatic concentrations of the lysine analogs, additional boluses might be considered in the presence of bleeding and/or when signs of fibrinolytic activations are observed on viscoelastic hemostatic assays.

The effects of corrective surgery on endothelial biomarkers and anthropometric data in children with congenital heart disease

Objective To investigate the influence of surgical correction on biomarkers of endothelial dysfunction in children with congenital heart disease and to evaluate anthropometric data. Methods Children with pulmonary hypertension (PH) or Tetralogy of Fallot (TOF) who were scheduled for corrective surgery were enrolled in this prospective study. Age-matched healthy children were included as controls. Demographic, haemodynamic and cardiac ultrasonography data were collected. Blood samples were taken pre-surgery, 24-48 hours post-surgery and again 3-6 months later. Several biomarkers (protein C, soluble platelet selectin [CD62P], soluble endothelium selectin [CD62E], soluble leukocyte selectin [CD62L], plasma von Willebrand Factor [vWF] atrial natriuretic peptide [ANP], brain natriuretic peptide[(BNP] and insulin-like growth factor-1 [IGF-1]) were measured. Results Sixty-three children (32 with PH, 15 with TOF, and 16 controls) were enrolled. No significant differences between the PH and TOF groups were observed in the expression of biomarkers pre- and post-surgery. IGF-1 levels were closely related to anthropometric data, particularly those children with PH. Expression of IGF-1 and weight/height normalized after corrective surgery. Conclusions No significant endothelial dysfunction was observed in children with PH or TOF before or after corrective surgery. Significant retardation of growth, particularly weight, was found before surgery and may be related to IGF-1 suppression.

Purification and characterization of tenerplasminin-1, a serine peptidase inhibitor with antiplasmin activity from the coral snake (Micrurus tener tener) venom

A plasmin inhibitor, named tenerplasminin-1 (TP1), was isolated from Micrurus tener tener (Mtt) venom. It showed a molecular mass of 6542Da, similarly to Kunitz-type serine peptidase inhibitors. The amidolytic activity of plasmin (0.5nM) on synthetic substrate S-2251 was inhibited by 91% following the incubation with TP1 (1nM). Aprotinin (2nM) used as the positive control of inhibition, reduced the plasmin amidolytic activity by 71%. Plasmin fibrinolytic activity (0.05nM) was inhibited by 67% following incubation with TP1 (0.1nM). The degradation of fibrinogen chains induced by plasmin, trypsin or elastase was inhibited by TP1 at a 1:2, 1:4 and 1:20 enzyme:inhibitor ratio, respectively. On the other hand, the proteolytic activity of crude Mtt venom on fibrinogen chains, previously attributed to metallopeptidases, was not abolished by TP1. The tPA-clot lysis assay showed that TP1 (0.2nM) acts like aprotinin (0.4nM) inducing a delay in lysis time and lysis rate which may be associated with the inhibition of plasmin generated from the endogenous plasminogen activation. TP1 is the first serine protease plasmin-like inhibitor isolated from Mtt snake venom which has been characterized in relation to its mechanism of action, formation of a plasmin:TP1 complex and therapeutic potential as anti-fibrinolytic agent, a biological characteristic of great interest in the field of biomedical research. They could be used to regulate the fibrinolytic system in pathologies such as metastatic cancer, parasitic infections, hemophilia and other hemorrhagic syndromes, in which an intense fibrinolytic activity is observed.

Cyanotic congenital heart disease (CCHD): focus on hypoxemia, secondary erythrocytosis, and coagulation alterations

Children with cyanotic congenital heart disease (CCHD) have complex alterations in their whole blood composition and coagulation profile due to long-standing hypoxemia. Secondary erythrocytosis is an associated physiological response intended to increase circulating red blood cells and oxygen carrying capacity. However, this response is frequently offset by an increase in whole blood viscosity that paradoxically reduces blood flow and tissue perfusion. In addition, the accompanying reduction in plasma volume leads to significant deficiencies in multiple coagulation proteins including platelets, fibrinogen and other clotting factors. On the one hand, these patients may suffer from severe hyperviscosity and subclinical 'sludging' in the peripheral vasculature with an increased risk of thrombosis. On the other hand, they are at an increased risk for postoperative hemorrhage due to a complex derangement in their hemostatic profile. Anesthesiologists caring for children with CCHD and secondary erythrocytosis need to understand the pathophysiology of these alterations and be aware of available strategies that lessen the risk of bleeding and/or thrombosis. The aim of this review is to provide an updated analysis of the systemic effects of long-standing hypoxemia in children with primary congenital heart disease with a specific focus on secondary erythrocytosis and hemostasis.

Pediatric transplantation: managing bleeding

There has been extraordinary progress over the last half-century in the field of medical transplantation in which tissue, organs, or body parts from one human are placed into another. Solid organ transplants have allowed thousands of children with otherwise devastating inherited or acquired disorders to survive. Depending upon the clinical situation, there are many specific peri-transplant issues that must be carefully addressed to optimize outcomes. Although surgical, immunologic, and infectious concerns are usually in the forefront, important aspects regarding hemostasis frequently arise. The number of solid organs that can be successfully transplanted in children has expanded over the last decades and includes kidney, liver, heart, lung, intestine, pancreas, and thymus. Bleeding complications may occur in the setting of organ failure prior to transplantation, during the surgical procedure, or in the post-transplant setting, and can results in significant morbidity. This report will focus on preventing and managing non-surgical-related bleeding complications in children undergoing liver, heart, kidney transplantation, in whom there are often unique aspects of coagulation to be considered.

Pharmacokinetics of Tranexamic Acid in Neonates, Infants, and Children Undergoing Cardiac Surgery with Cardiopulmonary Bypass

Background:

Tranexamic acid (TXA) is one of the most commonly used antifibrinolytic medications in children undergoing repair of congenital heart defects. However, a pharmacokinetics analysis of TXA has never been performed in neonates or young children undergoing complex cardiac surgeries using cardiopulmonary bypass, hypothermia, circulatory arrest, and ultrafiltration. A comprehensive pharmacokinetics study was performed in this patient population.

Methods:

Fifty-five patients ranging from 2 days through 4 yr old were categorized into three groups: children less than 2 months old, infants 2 months to 1 yr old, and children greater than 1 yr old and weighing up to 20 kg. TXA was given as a bolus of 100 mg/kg followed by an infusion of 10 mg · kg−1 · h−1 throughout the surgery. A dose of 100 mg/kg was placed in the cardiopulmonary bypass prime. A total of 16 to 18 samples were obtained from all patients throughout surgery. Plasma TXA concentrations were measured by high-performance liquid chromatography and modeled under a nonlinear mixed-effects framework with a two-compartment structural model.

Results:

Cardiopulmonary bypass had a statistically significant impact on all pharmacokinetic parameters. Age was a better covariate than body weight, affecting both the distribution and the elimination of TXA. However, weight performed well in some cases. Other covariates including body surface area, pump prime volume, ultrafiltrate volume, and body temperature did not improve the model.

Conclusions:

This TXA pharmacokinetic analysis is reported for the first time in neonates and young children undergoing complex cardiac surgeries with cardiopulmonary bypass. Dosing recommendations are provided as guidance for maintaining desired target concentrations.

The relative efficacy of antifibrinolytics in adolescent idiopathic scoliosis: a prospective randomized trial

BACKGROUND

Antifibrinolytics can reduce intraoperative blood loss. The primary aim of this study was to determine the efficacy of intraoperative tranexamic acid, epsilon-aminocaproic acid, and placebo at reducing perioperative blood loss and the transfusion rate in patients with adolescent idiopathic scoliosis undergoing posterior spinal arthrodesis.

METHODS

This is a prospective, randomized, double-blind comparison of tranexamic acid, epsilon-aminocaproic acid, and placebo used intraoperatively in patients with adolescent idiopathic scoliosis. One hundred and twenty-five patients with adolescent idiopathic scoliosis were randomly assigned to the tranexamic acid, epsilon-aminocaproic acid, or control groups. Parameters recorded included estimated blood loss, hematocrit, blood product usage, drain output, and total blood losses. The primary outcomes were intraoperative blood loss and postoperative drainage. Secondary outcomes were transfusion requirements and hematocrit changes both intraoperatively and postoperatively.

RESULTS

One hundred and twenty-five patients (ninety-seven female and twenty-eight male, with a mean age of fifteen years) were randomized to receive tranexamic acid (thirty-six patients), epsilon-aminocaproic acid (forty-two patients), or saline solution (forty-seven patients). The groups were similar at baseline, with one exception: the saline solution group had a higher estimated blood volume at baseline than the tranexamic acid group. Both tranexamic acid and epsilon-aminocaproic acid reduced the estimated blood loss per degree and estimated blood loss per pedicle screw. Epsilon-aminocaproic acid, but not tranexamic acid, reduced estimated blood loss and estimated blood loss per level. Tranexamic acid also reduced total blood losses compared with epsilon-aminocaproic acid or saline solution. In an analysis controlling for level, degree, and number of anchors, tranexamic acid reduced drain output and total blood losses. Tranexamic acid or epsilon-aminocaproic acid had a smaller decrease in hematocrit postoperatively. In an analysis controlling for the mean arterial pressure during surgical exposure, tranexamic acid reduced estimated blood loss and total blood losses. Overall, antifibrinolytics (tranexamic acid or epsilon-aminocaproic acid) reduced estimated blood loss, total blood losses, and the decline in hematocrit postoperatively compared with saline solution. There was no difference among the groups with respect to the transfusion rate, duration of surgery, levels fused, or pedicle screws placed.

CONCLUSIONS

Tranexamic acid and epsilon-aminocaproic acid reduced operative blood loss but not transfusion rate. Tranexamic acid is more effective at reducing postoperative drainage and total blood losses compared with epsilon-aminocaproic acid. Maintenance of the mean arterial pressure at &lt;75 mm Hg during surgical exposure appears to be critical for maximizing antifibrinolytic benefit.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

The efficacy of antifibrinolytic drugs in children undergoing noncardiac surgery: a systematic review of the literature

Children undergoing major surgery are frequently exposed to a high risk of blood loss often requiring transfusion. Although the risks associated with blood product transfusion have considerably decreased over the last decade, transfusion is still associated with significant morbidity and mortality. Thus, rigorous efforts should be made to decrease surgical bleeding and the need for blood product transfusion. Antifibrinolytic drugs have been shown to be effective when used in both adult and pediatric surgical patients. While there are data in adults to support safety, data remain limited for pediatric patients. Since the restriction of aprotinin use in 2008, the most commonly used antifibrinolytic drugs have been the lysine analogs, tranexamic acid (TXA), and ε-aminocaproic acid, which inhibit the conversion of plasminogen to plasmin and decrease the degree of fibrinolysis. We performed a systematic review of the literature pertaining to the efficacy of antifibrinolytic drugs in children undergoing noncardiac surgery. During spine surgery, both TXA and ε-aminocaproic acid decrease blood loss and transfusion requirements; however, this information comes from small, mainly retrospective trials. Two prospective, randomized, controlled trials have tested the efficacy of TXA in children undergoing craniofacial surgery and have reported that TXA decreases transfusion requirements. Two pharmacokinetic trials were also recently published and are summarized in this review. No data have been published regarding the efficacy of TXA administration in the pediatric trauma population. Further data are still needed in this field of study, and we discuss some perspectives for future research.

Influence of resuscitation fluids, fresh frozen plasma and antifibrinolytics on fibrinolysis in a thrombelastography-based, in-vitro, whole-blood model

Hyperfibrinolysis has been identified as a mechanism of trauma coagulopathy associated with poor outcome. The aim of the study was to create a trauma coagulopathy model (TCM) with a hyperfibrinolysis thrombelastography (TEG) pattern similar to injured patients and test the effects of different resuscitation fluids and antifibrinolytics on fibrinolysis. TCM was established from whole blood by either 15% dilution with isotonic saline, lactated Ringer's, Plasma-Lyte, 5% albumin, Voluven, Hextend, 6% dextran in isotonic saline or 30% dilution with lactated Ringer's plus Voluven and supplementation with tissue factor and tissue plasminogen activator (tPA). These combinations resulted in a TCM that could then be 'treated' with tranexamic acid (TXA) or 6-aminocaproic acid (ACA). Clot formation was evaluated by TEG. Whole-blood dilution by 15% with crystalloids and albumin in the presence of tissue factor plus tPA resulted in an abnormal TEG pattern and increased fibrinolysis, as did dilution with synthetic colloids. TXA 1 μg/ml or ACA 10 μg/ml were sufficient to suppress fibrinolysis when TCM was diluted 15% with lactated Ringer's, but 3 μg/ml of TXA or 30 μg/ml of ACA were needed for fibrinolysis inhibition induced by simultaneous euvolemic dilution with lactated Ringer's plus Voluven by 30%. A total of 15% dilution of whole blood in the presence of tissue factor plus tPA results in a hyperfibrinolysis TEG pattern similar to that observed in severely injured patients. Synthetic colloids worsen TEG variables with a further increase of fibrinolysis. Low concentrations of TXA or ACA reversed hyperfibrinolysis, but the efficient concentrations were dependent on the degree of fibrinolysis and whole-blood dilution.

Bleeding and Thrombotic Emergencies in Pediatric Cardiac Intensive Care

Children in the cardiac intensive care unit (CICU) with congenital or acquired heart disease are at risk for hematologic complications, both hemorrhage and thrombosis. The overall incidence of hematologic complications in the CICU is unknown, but risk factors and target groups have been identified where the essential physiologic balance between bleeding and clotting has been disrupted. Although the best management of life-threatening bleeding and clotting is prevention, the cardiac intensivist is often faced with managing life-threatening hematologic events involving patients from within the unit or those who present from outside. Part I of this review deals with the propensity of children with congenital and acquired heart disease to complications of both bleeding and clotting, and includes discussions of perioperative bleeding, thromboses in single-ventricle patients, clotting of Blalock-Taussig shunts and thrombotic complications of mechanical valves. Part II deals with the subject of stroke in children with heart disease. Part III reviews monitoring the effectiveness of anticoagulation and thrombolysis in the CICU. Currently available diagnostics modalities, medications and management strategies are reviewed and future directions discussed.

Effect of tranexamic acid on blood loss in pediatric cardiac surgery: a randomized trial

PURPOSE

The benefit of tranexamic acid (TXA) in pediatric cardiac surgery on postoperative bleeding has varied among studies. It is also unclear whether the effects of TXA differ between cyanotic patients and acyanotic patients. The aim of this study was to test the benefit of TXA in pediatric cardiac surgery in a well-balanced study population of cyanotic and acyanotic patients.

METHODS

A total of 160 pediatric patients undergoing cardiac surgery with cardiopulmonary bypass (81 cyanotic, 79 acyanotic) were included in this single-blinded, randomized trial at a tertiary care university-affiliated teaching hospital. Eighty-one children (41 cyanotic, 40 acyanotic) were randomly assigned to a TXA group, in which they received 50 mg/kg of TXA as a bolus followed by 15 mg/kg/h infusion and another 50 mg/kg into the bypass circuit. The other 79 patients were randomly assigned to a placebo group. The primary end point was the amount of 24-h blood loss.

RESULTS

The amount of 24-h blood loss was significantly less in the TXA group than in the placebo group [mean (95% confidence interval): 18.6 (15.8-21.4) vs. 23.5 (19.4-27.5) ml/kg, respectively; mean difference -4.9 (-9.7 to -0.01) ml/kg; p = 0.049]. This effect of TXA was already significant at 6 h [9.5 (7.5-11.5) vs. 13.2 (10.6-15.9) ml/kg, respectively; mean difference -3.47 (-7.0 to -0.4) ml/kg; p = 0.027]. However, there was no significant difference in the amount of blood transfusion between the groups. There was also no statistical difference in the effect of TXA in each cyanotic and acyanotic subgroup.

CONCLUSION

TXA can reduce blood loss in pediatric cardiac surgery but not the transfusion requirement (http://ClinicalTrials.gov number NCT00994994).

Cost-effectiveness analysis of administering tranexamic acid to bleeding trauma patients using evidence from the CRASH-2 trial

Objective

To assess the cost effectiveness of giving tranexamic acid (TXA) to bleeding trauma patients in low, middle and high income settings.

Methods

The CRASH-2 trial showed that TXA administration reduces the risk of death in bleeding trauma patients with a small but statistically significant increase in non-intensive care stay. A Markov model was used to assess the cost effectiveness of TXA in Tanzania, India and the United Kingdom (UK). The health outcome was the number of life years gained (LYs). Two costs were considered: the cost of administering TXA and the cost of additional days in hospital. Cost data were obtained from hospitals, World Health Organization (WHO) database and UK reference costs. Cost-effectiveness was measured in international dollars ($) per LY. Both deterministic and probabilistic sensitivity analyses were performed to test the robustness of the results to model assumptions.

Findings

Administering TXA to bleeding trauma patients within three hours of injury saved an estimated 372, 315 and 755 LYs per 1,000 trauma patients in Tanzania, India and the UK respectively. The cost of giving TXA to 1,000 patients was $17,483 in Tanzania, $19,550 in India and $30,830 in the UK. The incremental cost of giving TXA versus not giving TXA was $18,025 in Tanzania, $20,670 in India and $48,002 in the UK. The estimated incremental cost per LY gained of administering TXA is $48, $66 and $64 in Tanzania, India and the UK respectively.

Conclusion

Early administration of TXA to bleeding trauma patients is likely to be highly cost effective in low, middle and high income settings.

Trial Registration

This paper uses data collected by the CRASH 2 trial: Controlled-Trials.com ISRCTN86750102, Clinicaltrials.govNCT00375258 and South African Clinical Trial Register DOH-27-0607-1919.

Transfusion-free anesthetic management for open heart surgery in a neonate -A case report-

In small infants or neonates, open heart surgery without transfusion can have many risks regarding inadequate oxygen delivery and coagulopathy. However, if parents refuse blood transfusion, cardiac surgery without transfusion should be considered. We report a case of bloodless cardiac surgery in a 2.89 kg neonate with Jehovah's Witness parents. Blood conserving strategies were used. Preoperatively, erythropoietin and iron were supplemented to increase the hemoglobin level. Intraoperatively, techniques for minimizing blood loss were used, such as reducing priming volume for cardiopulmonary bypass, a blood salvage system, and modified ultrafiltration. Postoperatively, pharmacologic agents were administered and blood sampling was minimized.

Coagulation considerations for infants and children undergoing cardiopulmonary bypass

Cardiac surgery involving cardiopulmonary bypass imposes a significant pathophysiologic burden on patients. Pediatric patients are especially predisposed to the adverse effects of surgery and bypass on the coagulation system, with resultant bleeding, transfusion, and poor outcomes. These risks accrue to pediatric patients in inverse proportion to their weight and are attributable to hematologic immaturity, coagulation defects associated with congenital heart disease, bypass equipment, and the nature of congenital heart surgery. Standard anticoagulation does not completely inhibit thrombin generation, and continuous consumption of coagulation factor continues throughout bypass. Conventional measurements of anticoagulation during bypass poorly reflect this incomplete anticoagulation, and alternate methods may improve anticoagulant therapy. Emerging therapies for blocking the effects of bypass on the coagulation system hold promise for decreasing bleeding and related complications, and improving outcomes in congenital heart surgery.

Safety of aprotinin in congenital heart operations: results from a large multicenter database

BACKGROUND

Aprotinin was used frequently in children undergoing congenital heart operations with the aim of reducing bleeding, until it was taken off the market after adult studies reported increased renal failure and death. We evaluated the safety of aprotinin in a large multicenter cohort of children undergoing congenital heart operations.

METHODS

The Pediatric Health Information Systems Database was used to evaluate aprotinin in children (aged 0 to 18 years) undergoing congenital heart operations at 35 children's hospitals from 2003 to 2007. Propensity scores were constructed to account for potential confounders of age, sex, race, prematurity, genetic syndrome, type of operation (Risk Adjustment in Congenital Heart Surgery-1 category), center, and center volume. Multivariable analysis, adjusting for propensity score and individual covariates was performed to evaluate in-hospital mortality, postoperative renal failure requiring dialysis, and length of stay. Subanalysis was performed in the high-risk cohort undergoing reoperation.

RESULTS

The study included 30,372 patients (56% male) who were a median age of 7 months (interquartile range, 36 days to 3.2 years). Overall, 44% received aprotinin. Multivariable analysis found no difference in postoperative mortality (odds ratio, 1.00; 95% confidence interval [CI], 0.99 to 1.01), dialysis (odds ratio, 1.00; 95% CI, 0.99 to 1.01), or length of stay (least square mean difference, -0.44 days; 95% CI, -1.01 to 0.13) between aprotinin recipients and nonrecipients. No difference was found in mortality or dialysis in patients undergoing reoperation. Aprotinin recipients in the reoperation subgroup had significantly reduced length of stay (least square mean difference, -2.05 days; 95% CI -3.29 to -0.81),

CONCLUSIONS

These data suggest aprotinin is not associated with increased mortality or dialysis in children undergoing congenital heart operations and that further evaluation of aprotinin in this population could be undertaken without undue risk.