A Practical Tranexamic Acid Dosing Scheme Based on Population Pharmacokinetics in Children Undergoing Cardiac Surgery

Perioperative considerations in the paediatric patient with congenital and acquired coagulopathy

Neonates, infants, and children undergoing major surgery or with trauma can develop severe coagulopathy perioperatively. Neonates and infants are at highest risk because their haemostatic system is not fully developed and underlying inherited bleeding disorders may not have been diagnosed before surgery. Historically, laboratory coagulation measurements have been used to diagnose and monitor coagulopathies. Contemporary dynamic monitoring strategies are evolving. Viscoelastic testing is increasingly being used to monitor coagulopathy, particularly in procedures with a high risk of bleeding. However, there is a lack of valid age-specific reference values for diagnosis and trigger or target values for appropriate therapeutic management. A promising screening tool of primary haemostasis that may be used to diagnose quantitative and qualitative platelet abnormalities is the in vitro closure time by platelet function analyser. Targeted individualised treatment strategies for haemostatic bleeding arising from inherited or acquired bleeding disorders may include measures such as tranexamic acid, administration of plasma, derived or recombinant factors such as fibrinogen concentrate, or allogeneic blood component transfusions (plasma, platelets, or cryoprecipitate). Herein we review current recommended perioperative guidelines, monitoring strategies, and treatment modalities for the paediatric patient with a coagulopathy. In the absence of data from adequately powered prospective studies, it is recommended that expert consensus be considered until additional research and validation of goal-directed perioperative bleeding management in paediatric patients is available.

Intraoperative tranexamic acid administration in cranial meningioma surgery: a meta-analysis of prospective randomized, double-blinded, and placebo-controlled trials

Objective

Cranial meningioma surgeries often involve significant blood loss and transfusions. Tranexamic acid (TXA) has been used to reduce blood loss in various surgeries. This meta-analysis of randomized placebo-controlled trials (RCTs) evaluates the impact of TXA in cranial meningioma surgery.

Methods

Pubmed, Web of Science, and Cochrane Library were searched for RCTs. Studies were compared for: Blood loss, operative time, hospital stay, reoperation rates, allogeneic and autologous transfusion, and incidence of complications.

Results

Seven RCTs with 490 patients receiving TXA and 491 receiving placebos were included. TXA significantly shortened operative time (Mean Difference (MD): -20.95; 95%CI: -39.94 to -1.95; p=0.03). Blood loss was lower with TXA (MD: -262.7 ml; 95%CI: -397.6 to -127.8; p=0.0001). Odds of reoperation were not significantly different (OR: 0.44; 95%CI: 0.13-1.45; p=0.18). TXA significantly reduced the need for RBC transfusions (OR: 0.47; 95%CI: 0.22-0.99; p<0.05). No significant differences were observed regarding postoperative seizures (OR: 1.06; 95%CI: 0.56-2.03; p=0.85), hydrocephalus (OR: 0.25; 95%CI: 0.03-2.29; p=0.22), or hematoma (OR: 0.52; 95%CI: 0.22-1.28; p=0.16). Hospital stay was shortened in the TXA group (MD: -1.23; 95%CI: -2.41 to -0.05; p=0.04).

Conclusion

This meta-analysis suggests that a single intraoperative dose of TXA reduces blood loss, allogeneic blood transfusions and shortens surgery time.

New surgical technique for non-missile trauma hemostasis as a result of sewing needle

Traumas are the most important cause of mortality in the pediatric population. Bleeding is an important complication, especially in traumatic brain injuries with coagulation problem addition. Low-velocity penetrating brain injuries may be caused by sewing needles, nails, and knives. There are few studies in the literature for this injury type. This study presented a surgical technique and treatment to increase hemostasis in a 2-year-old patient after a sewing needle injury.

Current Status of Pharmacokinetic Research in Children: A Systematic Review of Clinical Trial Records

BACKGROUND

Many medications have different pharmacokinetics in children than in adults. Knowledge about the safety and efficacy of medications in children requires research into the pharmacokinetic profiles of children's medicines. By analysing registered clinical trial records, this study determined how frequently pharmacokinetic data is gathered in paediatric drug trials.

METHODS

We searched for the pharmacokinetic data from clinical trial records for preterm infants and children up to the age of 16 from January 2011 to April 2022. The records of trials involving one or more drugs in preterm infants and children up to the age of 16 were examined for evidence that pharmacokinetic data would be collected.

RESULTS

In a total of 1483 records of interventional clinical trials, 136 (9.17%) pharmacokinetic data involved adults. Of those 136 records, 60 (44.1%) records were pharmacokinetics trials involving one or more medicines in children up to the age of 16.20 (33.3%) in America, followed by 19 (31.6%) in Europe. Most trials researched medicines in the field of infection or parasitic diseases 20 (33.3%). 27 (48.2%) and 26 (46.4%) trials investigated medicines that were indicated as essential medicine.

CONCLUSION

The pharmacokinetic characteristics of children's drugs need to be better understood. The current state of pharmacokinetic research appears to address the knowledge gap in this area adequately. Despite slow progress, paediatric clinical trials have experienced a renaissance as the significance of paediatric trials has gained international attention. The outcome of paediatric trials will have an impact on children's health in the future. In recent years, the need for greater availability and access to safe child-size pharmaceuticals has received a lot of attention.

The influence of cardiopulmonary bypass on pediatric pharmacokinetics

INTRODUCTION

Every year thousands of children undergo surgery for congenital heart disease. Cardiac surgery requires the use of cardiopulmonary bypass, which can have unexpected consequences for pharmacokinetic parameters.

AREAS COVERED

We describe the pathophysiological properties of cardiopulmonary bypass that may influence pharmacokinetic parameters, with a focus on literature published in the last 10 years. We performed a PubMed database search with the keywords 'Cardiopulmonary bypass' AND 'Pediatric' AND 'Pharmacokinetics'. We searched related articles on PubMed and checked the references of articles for relevant studies.

EXPERT OPINION

Interest in the influence of cardiopulmonary bypass on pharmacokinetics has increased over the last 10 years, especially due to the use of population pharmacokinetic modeling. Unfortunately, study design usually limits the amount of information that can be obtained with sufficient power and the best way to model cardiopulmonary bypass is yet unknown. More information is needed on the pathophysiology of pediatric heart disease and cardiopulmonary bypass. Once adequately validated, PK models should be integrated in the patient electronic database integrating covariates and biomarkers influencing PK, making it possible to predict real-time drug concentrations and guide further clinical management for the individual patient at the bedside.

Tranexamic acid administered during cesarean delivery in high-risk patients: maternal pharmacokinetics, pharmacodynamics, and coagulation status

BACKGROUND

Tranexamic acid is frequently administered for postpartum hemorrhage. The World Health Organization recommends 1 g intravenous dosing, repeated once after 30 minutes for ongoing bleeding. Understanding the pharmacokinetics and pharmacodynamics of tranexamic acid in patients at high risk of postpartum hemorrhage may enable dosage tailoring for optimal antifibrinolysis with minimal adverse events, such as thrombosis or renal cortical necrosis.

OBJECTIVE

This study aimed to report tranexamic acid pharmacokinetics and pharmacodynamics after 1 g intravenous dosing during cesarean delivery in patients at risk of hemorrhage. The primary endpoint was tranexamic acid plasma concentration of >10 μg/mL, known to inhibit 80% of fibrinolysis. In addition, the correlation between patient demographics and rotational thromboelastometry coagulation changes were analyzed.

STUDY DESIGN

In this prospective study, 20 women aged 18 to 50 years, ≥23 weeks of gestation undergoing cesarean delivery with at least 1 major (placenta previa, suspected placenta accreta spectrum, or active bleeding) or 2 minor (≥2 previous cesarean deliveries, previous postpartum hemorrhage, chorioamnionitis, polyhydramnios, macrosomia, obesity, or suspected placental abruption) risk factors for postpartum hemorrhage were recruited. The exclusion criteria were allergy to tranexamic acid, inherited thrombophilia, previous or current thrombosis, seizure history, renal or liver dysfunction, anticoagulation, or category III fetal heart tracing. Tranexamic acid 1 g was administered after umbilical cord clamping. Blood samples were drawn at 3, 7, 15, and 30 minutes and then at 30-minute intervals up to 5 hours. Plasma concentrations were evaluated as mean (standard error). Serial rotational thromboelastometry was performed and correlated with tranexamic acid plasma concentrations.

RESULTS

The median age of participants was 37.5 years (interquartile range, 35.0-39.5), and the median body mass index was 28.6 kg/m2 (interquartile range, 24.9-35.0). The median blood loss (estimated or quantitative) was 1500 mL (interquartile range, 898.5-2076.0). Of note, 9 of 20 (45%) received a transfusion of packed red blood cells. The mean peak tranexamic acid plasma concentration at 3 minutes was 59.8±4.7 μg/mL. All patients had a plasma concentration >10 μg/mL for 1 hour after infusion. Plasma concentration was >10 μg/mL in more than half of the patients at 3 hours and fell <10 μg/mL in all patients at 5 hours. There was a moderate negative correlation between body mass index and the plasma concentration area under the curve (r=-0.49; 95% confidence interval, -0.77 to -0.07; P=.026). Rotational thromboelastometry EXTEM maximum clot firmness had a weak positive correlation with longitudinal plasma concentration (r=0.32; 95% confidence interval, 0.21-0.46; P<.001). EXTEM maximum clot lysis was 0% after infusion in 18 patients (90%), and no patient in the study demonstrated a maximum lysis of >15% at any interval from 3 minutes to 5 hours. There was no significant correlation between EXTEM clot lysis at 30 minutes and longitudinal tranexamic acid plasma concentrations (r=0.10; 95% confidence interval, -0.20 to 0.19; P=.252).

CONCLUSION

After standard 1 g intravenous dosing of tranexamic acid during cesarean delivery in patients at high risk of hemorrhage, a plasma concentration of ≥10 μg/mL was sustained for at least 60 minutes. Plasma tranexamic acid levels correlated inversely with body mass index. The concurrent use of rotational thromboelastometry may demonstrate tranexamic acid's impact on clot firmness but not a hyperfibrinolysis-derived trigger for therapy.

Prophylactic Use of Antifibrinolytics During Pediatric Cardiac Surgery With Cardiopulmonary Bypass on Postoperative Bleeding and Transfusion: A Systematic Review and Meta-Analysis

OBJECTIVES

To determine the effect of intraoperative antifibrinolytics, including tranexamic acid (TXA), aminocaproic acid (EACA), or aprotinin, on bleeding in children undergoing cardiac surgery with cardiopulmonary bypass (CPB).

DATA SOURCES

Relevant articles were systematically searched from Ovid MEDLINE, Ovid EMBASE, CINAHL, Cochrane Library, and Web of Science to November 15, 2021.

STUDY SELECTION

Abstracts were screened, and full texts were reviewed using predetermined inclusion and exclusion criteria using the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline.

DATA EXTRACTION

A standardized data extraction tool was used.

DATA SYNTHESIS

Sixty-eight studies including 28,735 patients were analyzed. TXA compared with placebo resulted in a mean decrease in chest tube output of 9.1 mL/kg (95% CI, 6.0-12.3 mL/kg), I2 equals to 65.2%, p value of less than 0.001, platelet requirement of 2.9 mL/kg (95% CI, 0.1-5.8 mL/kg), I2 =72.5%, p value less than 0.001 and plasma requirement of 4.0 mL/kg (95% CI, 0.6-7.2 mL/kg), I2 equals to 94.5%, p value less than0.001. Aprotinin compared with placebo resulted in a mean decrease in chest tube output of 4.3 mL/kg (2.4-6.2 mL/kg), I2 equals to 66.3%, p value of less than 0.001, platelet transfusion of 4.6 mL/kg (95% CI, 0.6-8.6 mL/kg), I2 equals to 93.6%, p value of less than 0.001, and plasma transfusion of 7.7 mL/kg (95% CI, 2.1-13.2 mL/kg), I2 equals to 95.3%, p value of less than 0.001. EACA compared with placebo resulted in a mean decrease in chest tube output of 9.2 mL/kg (2.3-21.0 mL/kg), I2 equals to 96.4%, p value of less than 0.001, RBC transfusion of 7.2 mL/kg (95% CI, 2.4-12.1 mL/kg), I2 equals to 94.5%, p value equals to 0.002, and platelet transfusion of 10.7 mL/kg (95% CI, 2.9-18.5 mL/kg), I2 equals to 0%, p value of less than 0.001. No statistical difference was observed in chest tube output when TXA was compared with aprotinin. Subgroup analysis of cyanotic patients showed a significant decrease in chest tube output, platelet requirement, and plasma requirement for patients receiving aprotinin. Overall, the quality of evidence was moderate.

CONCLUSIONS

Antifibrinolytics are effective at decreasing blood loss and blood product requirement in children undergoing cardiac surgery with CPB although the quality of evidence is only moderate.

Clinical Validation of a Volumetric Absorptive Micro-Sampling Device for Pharmacokinetic Studies With Tranexamic Acid

We assessed the accuracy of tranexamic acid (TXA) concentrations measured in capillary whole blood using volumetric absorptive micro-sampling (VAMS) devices. Paired venous and VAMS capillary blood samples were collected from 15 healthy volunteers participating in a pharmacokinetic study of alternative routes (oral, IM and IV) of administering TXA. To assess accuracy across a range of concentrations, blood was drawn at different times after TXA administration. We measured TXA concentrations in plasma, whole blood from samples collected by venepuncture and whole blood from venous and capillary samples collected using VAMS devices. TXA was measured using a validated high sensitivity liquid chromatography - mass spectrometry method. We used Bland-Altman plots to describe the agreement between the TXA concentrations obtained with the different methods. In the 42 matched samples, the mean plasma TXA concentration was 14.0 mg/L (range 2.6-36.5 mg/L) whereas the corresponding whole blood TXA concentration was 7.7 mg/L (range 1.6-17.5 mg/L). When comparing TXA concentrations in VAMS samples of venous and capillary whole blood, the average bias was 0.07 mg/L (lower and upper 95% limits of agreement: -2.1 and 2.2 mg/L respectively). When comparing TXA concentrations in venous whole blood and VAMS capillary whole blood, the average bias was 0.7 mg/L (limits of agreement: -2.7 and 4.0 mg/L). Volumetric absorptive micro-sampling devices are sufficiently accurate for use in pharmacokinetic studies of tranexamic acid treatment in the range of plasma concentrations relevant for the assessment of fibrinolysis inhibition.

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.

Population pharmacokinetics and pharmacodynamics of Tranexamic acid in women undergoing caesarean delivery

AIMS

The population pharmacokinetics (PK) and pharmacodynamics (PD) of tranexamic acid (TXA) have not been studied to prevent postpartum haemorrhage (PPH) in pregnant women. It is unclear which TXA dose assures sufficient PPH prevention. This study investigated population PK/PD of TXA in pregnant women who underwent caesarean delivery to determine the optimal prophylactic doses of TXA for future studies.

METHODS

We analysed concentration (PK) and maximum lysis (PD) data from 30 pregnant women scheduled for caesarean delivery who received 5, 10 or 15 mg/kg of TXA intravenously using population approach.

RESULTS

TXA PK was best described by a two-compartment model with first-order elimination and the following parameters: clearance (between-subject variability) of 9.4 L/h (27.7%), central volume of 10.1 L (47.4%), intercompartmental clearance of 22.4 L/h (66.7%), peripheral volume of 14.0 L (13.1%) and additive error of 1.4 mg/L. The relationship between TXA concentration and maximum lysis was characterized by a sigmoid Emax model with baseline lysis of 97%, maximum inhibition of 89%, IC50 of 6.0 mg/L (65.3%), hill factor of 8.5 (86.3%) and additive error of 7.3%. Simulations demonstrated that 500 and 650 mg of TXA maintained therapeutic targets for 30 minutes and 1 hour, respectively, in 90% of patients.

CONCLUSION

This is the first population PK and PD study of TXA in pregnant women undergoing caesarean delivery. Our analysis suggests that a 650 mg dose provides adequate PPH prophylaxis up to 1 hour, which is less than the currently used 1000 mg of TXA in pregnant women.

Current Practices in Tranexamic Acid Administration for Pediatric Trauma Patients in the United States

BACKGROUND

Although controversial, early administration of tranexamic acid (TXA) has been shown to reduce mortality in adult patients with major trauma. Tranexamic acid has also been successfully used in elective pediatric surgery, with significant reduction in blood loss and transfusion requirements. There are limited data to guide its use in pediatric trauma patients. We sought to determine the current practices for TXA administration in pediatric trauma patients in the United States.

METHODS

A survey was conducted of all the American College of Surgeons-verified Level I and II trauma centers in the United States. The survey data underwent quantitative analysis.

RESULTS

Of the 363 Level I and II qualifying centers, we received responses from 220 for an overall response rate of 61%. Eighty of 99 verified pediatric trauma centers responded for a pediatric trauma center response rate of 81%. Of all responding centers, 148 (67%) reported they care for pediatric trauma patients, with an average of 513 pediatric trauma patients annually. The pediatric trauma centers report caring for an average of 650 pediatric trauma patients annually. Of all centers caring for pediatric trauma, 52 (35%) report using TXA, with the most common initial dosing being 15 mg/kg (68%). A follow-up infusion was utilized by 45 (87%) of the programs, most commonly dosed at 2 mg/kg/hr × 8 hr utilized by 24 centers (54%).

CONCLUSION

Although the clinical evidence for TXA in pediatric trauma patients is limited, we believe that consideration should be given for use in major trauma with hemodynamic instability or significant risk for ongoing hemorrhage. If available, resuscitation should be guided by thromboelastography to identify candidates who would most benefit from antithrombolytic administration. This represents a low-cost/low-risk and high-yield therapy for pediatric trauma patients.

WOMAN-PharmacoTXA trial: Study protocol for a randomised controlled trial to assess the pharmacokinetics and pharmacodynamics of intramuscular, intravenous and oral administration of tranexamic acid in women giving birth by caesarean section

Background: Intravenous tranexamic acid (TXA) within 3 hours of birth significantly reduces death due to bleeding in women with postpartum haemorrhage (PPH). Most PPH deaths occur in the first hours after giving birth and treatment delay decreases survival.  One barrier to rapid TXA treatment is the need for intravenous injection. Intramuscular injection and oral solution of TXA would be easier and faster to administer and would require less training. However, the pharmacokinetics (PK), pharmacodynamics and safety of TXA administered by different routes in pregnant women have not been established. The main aim of this study is to ascertain whether IM and oral solution of TXA will be absorbed at levels sufficient to inhibit fibrinolysis in pregnant women.

Methods: WOMAN-PharmacoTXA is a prospective, randomised, open label trial to be conducted in Zambia and Pakistan.  Adult women undergoing caesarean section with at least one risk factor for PPH will be included.  Women will be randomised to receive one of the following about 1 hour prior to caesarean section: 1-gram TXA IV, 1-gram TXA IM, 4-grams TXA oral solution or no TXA. Randomisation will continue until 120 participants with at least six post randomisation PK samples are included. TXA concentration in maternal blood samples will be measured at baseline and at different time points during 24 hours after receipt of intervention. Blood TXA concentration will be measured from the umbilical cord and neonate.

The primary endpoint is maternal blood TXA concentrations over time. Secondary outcomes include umbilical cord and neonate TXA concentration D-dimer concentration, blood loss and clinical diagnosis of PPH, injection site reactions and maternal and neonate adverse events.

Discussion: The WOMAN-PharmacoTXA trial will provide important data on pharmacokinetics, pharmacodynamics and safety of TXA after IV, intramuscular and oral administration in women giving birth by caesarean section.

Trial registration: ClincalTrials.gov, NCT04274335 (18/02/2020).

The synergistic effect of tranexamic acid and ethamsylate combination on blood loss in pediatric cardiac surgery

Background:

Pediatric patients are at risk for bleeding after cardiac surgery. Administration of antifibrinolytic agents reduces postoperative blood loss.

Objective:

Evaluation of the efficacy of combined administration of tranexamic acid (TXA) and ethamsylate in the reduction of postoperative blood loss in pediatric cardiac surgery.

Methods:

This prospective randomized study included 126 children submitted for cardiac surgery, and they were allocated into three groups: control group (n = 42); TXA group (n = 42):- received only TXA; and combined ethamsylate TXA group (n = 42):- received a combination of TXA and ethamsylate. The main collected data included sternal closure time, the needs for intraoperative transfusion of blood and its products, the total amount of blood loss, and the amount of the whole blood and its products transfused to the patients in the first 24 postoperative hours.

Results:

Blood loss volume in the first 24 postoperative hours was significantly smaller in combined group than the TXA and control groups and was significantly smaller in the TXA group than the control group. The sternal closure time was significantly shorter in the combined group than the other 2 groups and significantly shorter in TXA than the control group. The amount of whole blood transfused to patients in the combined group during surgery and in the first postoperative 24 h was significantly smaller than the other 2 groups and smaller in TXA group than the control group during surgery.

Conclusion:

Combined administration of ethamsylate and TXA in pediatric cardiac surgery was more effective in reducing postoperative blood loss and whole blood transfusion requirements than the administration of TXA alone.

Hypothesis for a partially non urinary elimination of tranexamic acid in haemorrhagic caesarean section: Traces pilot pharmacokinetic study: Pharmacokinetics of tranexamic acid in obstetrics

BACKGROUND

In previous studies, the choice of doses of tranexamic acid was empirically defined as no pharmacokinetic study had been conducted in haemorrhagic caesarean section.

OBJECTIVE

The objective was to build a pharmacokinetic model in patients receiving a single 0.5, 1 or 2 g intravenous bolus.

METHOD

A preliminary monocentric open study was performed in the Lille centre. Blood samples and one urinary sample were collected in the 6 h following the injection. Nine patients were included. Tranexamic acid concentration was measured using liquid chromatography system coupled with tandem mass spectrometry. We used Monolix 2019R1 for population pharmacokinetic modelling. A structural model was constructed followed by the investigation of potential covariates.

RESULTS

Data were best described with a two-compartment model with a double first-order elimination from the central compartment. The model was improved when the variable ideal weight per dose was affected as a covariate for the apparent volume of distribution. Assuming a dose of 1 g and a height of 160 cm, the pharmacokinetic parameters were estimated at 10.26 L.h^-1 for total clearance, 11.5 L for the volume of the central compartment, 15.8 L for the volume of the second compartment, a diffusional clearance of 30.36 L.h^-1 , and a urinary excretion fraction of 25.8%.

CONCLUSIONS

The population pharmacokinetic model of tranexamic acid in haemorrhagic caesarean section was successfully established in our tiny sample of patients. The results of this preliminary TRACES pharmacokinetic study suggested that elimination of tranexamic acid is partially non urinary in contrast with healthy patients.

Tranexamic acid quantification in human whole blood using liquid samples or volumetric absorptive microsampling devices

Background: Recent clinical trials demonstrate the benefits of the antifibrinolytic drug tranexamic acid but its pharmacokinetics remain to be investigated more in depth. Although pharmacokinetics studies are usually performed with plasma, volumetric absorptive microsampling devices allow us to analyze dried whole blood samples with several advantages. Materials & methods: High-sensitivity LC-MS/MS methods for the quantification of tranexamic acid in human whole blood using liquid samples or dry samples on volumetric absorptive microsampling devices were developed and validated based on International Association from Therapeutic Drug Monitoring and Clinical Toxicology, European Medicines Agency and US FDA guidance. Conclusion: The method performances were excellent across the range of clinically relevant concentrations. The stability of tranexamic acid in blood samples stored up to 1 month at +50°C was demonstrated. The methods' suitability was confirmed with clinical samples.

Experience in an Urban Level 1 Trauma Center With Tranexamic Acid in Pediatric Trauma: A Retrospective Chart Review

BACKGROUND

Evidence for tranexamic acid (TXA) in the pharmacologic management of trauma is largely derived from data in adults. Guidance on the use of TXA in pediatric patients comes from studies evaluating its use in cardiac and orthopedic surgery. There is minimal data describing TXA safety and efficacy in pediatric trauma. The purpose of this study is to describe the use of TXA in the management of pediatric trauma and to evaluate its efficacy and safety end points.

METHODS

This retrospective, observational analysis of pediatric trauma admissions at Hennepin County Medical Center from August 2011 to March 2019 compares patients who did and did not receive TXA. The primary end point is survival to hospital discharge. Secondary end points include surgical intervention, transfusion requirements, length of stay, thrombosis, and TXA dose administered.

RESULTS

There were 48 patients aged ≤16 years identified for inclusion using a massive transfusion protocol order. Twenty-nine (60%) patients received TXA. Baseline characteristics and results are presented as median (interquartile range) unless otherwise specified, with statistical significance defined as P < .05. Patients receiving TXA were more likely to be older, but there was no difference in injury type or Injury Severity Score at baseline. There was no difference in survival to discharge or thrombosis. Patients who did not receive TXA had numerically more frequent surgical intervention and longer length of stay, but these did not reach significance.

CONCLUSIONS

TXA was utilized in 60% of pediatric trauma admissions at a single level 1 trauma center, more commonly in older patients. Although limited by observational design, we found patients receiving TXA had no difference in mortality or thrombosis.

Patient Blood Management in Pediatric Cardiac Surgery: A Review

Efforts to reduce blood product transfusions and adopt blood conservation strategies for infants and children undergoing cardiac surgical procedures are ongoing. Children typically receive red blood cell and coagulant blood products perioperatively for many reasons, including developmental alterations of their hemostatic system, and hemodilution and hypothermia with cardiopulmonary bypass that incites inflammation and coagulopathy and requires systemic anticoagulation. The complexity of their surgical procedures, complex cardiopulmonary interactions, and risk for inadequate oxygen delivery and postoperative bleeding further contribute to blood product utilization in this vulnerable population. Despite these challenges, safe conservative blood management practices spanning the pre-, intra-, and postoperative periods are being developed and are associated with reduced blood product transfusions. This review summarizes the available evidence regarding anemia management and blood transfusion practices in the perioperative care of these critically ill children. The evidence suggests that adoption of a comprehensive blood management approach decreases blood transfusions, but the impact on clinical outcomes is less well studied and represents an area that deserves further investigation.

Damage Control Resuscitation

Damage control resuscitation (DCR) is a strategy for resuscitating patients from hemorrhagic shock to rapidly restore homeostasis. Efforts are focused on blood product transfusion with whole blood or component therapy closely approximating whole blood, limited use of crystalloid to avoid dilutional coagulopathy, hypotensive resuscitation until bleeding control is achieved, empiric use of tranexamic acid, prevention of acidosis and hypothermia, and rapid definitive surgical control of bleeding. Patients receiving uncrossmatched Type O blood in the emergency department and later receiving cumulative transfusions of 10 or more red blood cell units in the initial 24-hour post-injury (massive transfusion) are widely recognized as being at increased risk of morbidity and mortality due to exsanguination. Ideally, these patients should be rapidly identified, however anticipating transfusion needs is challenging. Useful indicators of massive transfusion reviewed in this guideline include: systolic blood pressure <110 mmHg, heart rate > 105 bpm, hematocrit <32%, pH < 7.25, injury pattern (above-the-knee traumatic amputation especially if pelvic injury is present, multi-amputation, clinically obvious penetrating injury to chest or abdomen), >2 regions positive on Focused Assessment with Sonography for Trauma (FAST) scan, lactate concentration on admission >2.5, admission international normalized ratio ≥1.2-1.4, near infrared spectroscopy-derived StO2 < 75% (in practice, rarely available), BD > 6 meq/L. Unique aspects of out-of-hospital DCR (point of injury, en-route, and remote DCR) and in-hospital (Medical Treatment Facilities: Role 2b/Forward surgical teams - role 3/ combat support hospitals) are reviewed in this guideline, along with pediatric considerations.

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.

Postpartum haemorrhage related early increase in D-dimers is inhibited by tranexamic acid: haemostasis parameters of a randomized controlled open labelled trial

BACKGROUND

Beneficial effects of tranexamic acid (TA) have been established in surgery and trauma. In ongoing postpartum haemorrhage (PPH), a moderate reduction of blood loss was observed in a previously published randomized controlled trial. Analysis of haemostasis parameters obtained from samples collected as part of this study are presented.

METHODS

Women with PPH >800 ml after vaginal delivery were assigned to receive either TA (4 g over 1 h, then 1 g per h over six h) (TA) or not (H). A non-haemorrhagic group (NH), <800 ml blood loss, was included as postpartum reference. At four time-points (enrolment, +30 min, +2 h, +6 h), haemostasis was assessed. Haemostasis assays were performed blinded to group allocation. Data were expressed as median [interquartiles] and compared with non-parametric tests.

RESULTS

In H compared with NH group, D-dimers increase (3730 ng ml(-1) [2468-8493] vs 2649 [2667-4375]; P=0.0001) and fibrinogen and factor II decrease were observed at enrolment and became maximal 2 h later. When comparing TA to H patients, the increase in Plasmin-Antiplasmin-complexes at +30 min (486 ng ml(-1) [340-1116] vs 674 [548-1640]; P=0.03) and D-dimers at +2 h (3888 ng ml(-1) [2688-6172] vs 7495 [4400-15772]; P=0.0001) was blunted. TA had no effect on fibrinogen decrease.

CONCLUSIONS

This study provides biological evidence of an early increase in D-dimers and plasmin-antiplasmin complexes associated with active post-partum haemorrhage and its attenuation by the early use of a clinically effective high dose of TA, opening the perspective of dose ranging studies to determinate the optimal dose and timing in this setting.

CLINICAL TRIAL REGISTRATION

ISRCTN09968140.

TRAnexamic acid in hemorrhagic CESarean section (TRACES) randomized placebo controlled dose-ranging pharmacobiological ancillary trial: study protocol for a randomized controlled trial

BACKGROUND

Evidence increases that a high or a standard dose of tranexamic acid (TA) reduces postpartum bleeding. The TRACES pharmacobiological substudy aims to establish a therapeutic strategy in hemorrhagic (H) Cesarean section (CS) with respect to the intensity of fibrinolysis by using innovative assays.

METHOD/DESIGN

The TRACES trial is a multicenter, randomized, double-blind, placebo-controlled, TA dose-ranging study that measures simultaneously plasmatic and uterine and urine TA concentrations and the plasmin peak inhibition tested by a simultaneous thrombin plasmin generation assay described by Van Geffen (novel hemostasis assay [NHA]). Patients undergoing H CS (>800 mL) will receive blindly TA 0.5 g or 1 g or placebo. A non-hemorrhagic (NH) group will be recruited to establish plasmin generation profile. Venous blood will be sampled before, at the end, and then at 30, 60, 120, and 360 min after injection. Uterine bleeding will be sampled after injection. Urine will be sampled 2 h and 6 h after injection. The number of patients entered into the study will be 114 H + 48 NH out of the 390 patients of the TRACES clinical trial.

DISCUSSION

To explore the two innovative assays, a preliminary pilot study was conducted. Blood samples were performed repeatedly in patients undergoing either a H (>800 mL) or NH (<800 mL) CS and in non-pregnant women (NP). H patients received TA (0-2 g). Dose-dependent TA plasmatic concentrations were determined by LC-MS/MS quantification. Plasmin generation and its inhibition were tested in vitro and in vivo using the simultaneous thrombin-plasmin generation assay (STPGA). The pilot study included 15 patients in the H group, ten patients in the NH group, and seven patients in the NP group. TA plasmatic concentration showed a dose-dependent variation. STPGA inter-assay variation coefficients were < 20% for all plasmin parameters. Inter-individual dispersion of plasmin generation capacity was higher in H and NH groups than in NP group. Profile evolution over time was different between groups. This preliminary technical validation study allows TRACES pharmacobiological trial to be conducted.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02797119. Registered on 13 June 2016.

Is tranexamic acid exposure related to blood loss in hip arthroplasty? A pharmacokinetic-pharmacodynamic study

AIMS

Tranexamic acid (TXA) is an antifibrinolytic agent, decreasing blood loss in hip arthroplasty. The present study investigated the relationship between TXA exposure markers, including the time above the in vitro threshold reported for inhibition of fibrinolysis (10 mg l^-1 ), and perioperative blood loss.

METHODS

Data were obtained from a prospective, double-blind, parallel-arm, randomized superiority study in hip arthroplasty. Patients received a preoperative intravenous bolus of TXA 1 g followed by a continuous infusion of either TXA 1 g or placebo over 8 h. A population pharmacokinetic study was conducted to quantify TXA exposure.

RESULTS

In total, 827 TXA plasma concentrations were measured in 166 patients. A two-compartment model fitted the data best, total body weight determining interpatient variability in the central volume of distribution. Creatinine clearance accounted for interpatient variability in clearance. At the end of surgery, all patients had TXA concentrations above the therapeutic target of 10 mg l^-1 . The model-estimated time during which the TXA concentration was above 10 mg l^-1 ranged from 3.3 h to 16.3 h. No relationship was found between blood loss and either the time during which the TXA concentration exceeded 10 mg l^-1 or the other exposure markers tested (maximum plasma concentration, area under the concentration-time curve).

CONCLUSION

In hip arthroplasty, TXA plasma concentrations were maintained above 10 mg l^-1 during surgery and for a minimum of 3 h with a preoperative TXA dose of 1 g. Keeping TXA concentrations above this threshold up to 16 h conferred no advantage with regard to blood loss.

Tranexamic acid for treatment and prophylaxis of bleeding and hyperfibrinolysis

Uncontrolled massive bleeding with subsequent derangement of the coagulation system is a major challenge in the management of both surgical and seriously injured patients. Under physiological conditions activators and inhibitors of coagulation regulate the sensitive balance between clot formation and fibrinolysis. In some cases, excessive and diffuse bleeding is caused by systemic activation of fibrinolysis, i. e. hyperfibrinolysis (HF). Uncontrolled HF is associated with a high mortality. Polytrauma patients and those undergoing surgical procedures involving organs rich in plasminogen proactivators (e. g. liver, kidney, pancreas, uterus and prostate gland) are at a high risk for HF. Antifibrinolytics, such as tranexamic acid (TXA) are used for prophylaxis and treatment of bleeding caused by a local or generalized HF as well as other hemorrhagic conditions. TXA is a synthetic lysine analogue that has been available in Austria since 1966. TXA is of utmost importance in the prevention and treatment of traumatic and perioperative bleeding due to the resulting reduction in perioperative blood loss and blood transfusion requirements. The following article presents the different fields of application of TXA with particular respect to indications and dosages, based on a literature search and on current guidelines.

Pharmacokinetics of tranexamic acid in neonates and infants undergoing cardiac surgery

AIM

Tranexamic acid (TXA) continues to be one of the antifibrinolytics of choice during paediatric cardiac surgery. However, in infants less than 1 year of age, the optimal dosing based on pharmacokinetic (PK) considerations is still under discussion.

METHODS

Forty-three children less than 1 year of age were enrolled, of whom 37 required the use of cardiopulmonary bypass (CPB) and six were operated on without CPB. Administration of 50 mg kg^-1 TXA intravenously at the induction of anaesthesia was followed by 50 mg kg^-1 into the CPB prime in the CPB group. Plasma concentrations of TXA were analysed by gas chromatography-mass spectrometry. PK data were investigated using nonlinear mixed-effect models.

RESULTS

A two-compartment model was fitted, with the main covariates being allometrically scaled bodyweight, CPB, postmenstrual age (PMA). Intercompartmental clearance (Q), peripheral volume (V2), systemic clearance, (CL) and the central volume (V1) were calculated. Typical values of the PK parameter estimates were as follows: CL = 3.78 [95 % confidence interval (CI) 2.52, 5.05] l h^-1 ; central volume of distribution = 13.6 (CI 11.7, 15.5) l; Q = 16.3 (CI 13.5, 19.2) l h^-1 ; V2 = 18.0 (CI 16.1, 19.9) l. Independently of age, 10 mg kg^-1 TXA as a bolus, a subsequent infusion of 10 mg kg^-1 h^-1 , then a 4 mg kg^-1 bolus into the prime and a reduced infusion of 4 mg kg^-1 h^-1 after the start of CPB are required to maintain TXA concentrations continuously above 20 μg ml^-1 , the threshold value for an effective inhibition of fibrinolysis and far lower than the usual peak concentrations (the '10-10-4-4 rule').

CONCLUSIONS

The introduction of a modified dosing regimen using a starting bolus followed by an infusion and a CPB prime bolus would prohibit the potential risk of seizures caused by high peak concentrations and also maintain therapeutic plasma concentration above 20 μg ml^-1 .

Effectiveness of tranexamic acid for reducing intraoperative bleeding in palatoplasties: A randomized clinical trial

BACKGROUND

Few data are available regarding blood loss during cleft palate surgery. This study assessed the effect of using tranexamic acid in the reduction of intraoperative bleeding.

METHODS

A double-blind, randomized clinical trial compared intraoperative bleeding and the incidence of oronasal fistulas after palatoplasties in a control group that was given placebo and an intervention group that was given 10 mg/kg tranexamic acid followed by a continuous infusion of 1 mg/kg/h of the same until the end of surgery. Patients who underwent primary palatoplasty with no known or suspected coagulation disorders at our institution during the study period were included in the study.

RESULTS

70 patients were allocated, 66 received the intervention. Blood loss was reduced by 11.9%, without statistical significance. The incidence of fistulas in the intervention and control groups was 12.9% and 18.75%, respectively. The reduction of 5.8% (CI 95%: 12%-23.8%) was not significant.

CONCLUSIONS

The reduction of intraoperative blood loss was lower than expected and not statistically significant; a larger sample is needed to confirm the observed reduction. The drug did not seem to have negative effects on flap viability.

Paediatric trauma resuscitation: an update

Purpose

Paediatric trauma is the leading cause of mortality in children. Paediatric trauma resuscitation is the first and foremost step towards a successful treatment and subsequent recovery. Significant advances have taken place in the last years in relation to this field of trauma care.

Methods

In this narrative review, we attempt to summarise the recent development in the concepts of fluid resuscitation, massive transfusion, permissive resuscitation, management of coagulopathy and use of tranexamic acid, literature pertaining to implementation of transfusion protocols in the paediatric population and education related to the paediatric trauma resuscitation.

Results/Conclusions

The current evidence although emerging is still sparse and high-quality studies are needed to shed more light on most of the above domains of resuscitation.

[Therapy of inherited diseases of platelet function. Interdisciplinary S2K guideline of the Permanent Paediatric Committee of the Society of Thrombosis and Haemostasis Research (GTH e. V.)]

Inherited disorders of platelet function are a heterogeneous group. For optimal prevention and management of bleeding, classification and diagnosis of the underlying defect are highly recommended. An interdisciplinary guideline for a diagnostic approach has been published (AWMF # 086-003 S2K; Hämostaseologie 2014; 34: 201-212). Underlying platelet disorder, platelet count, age and clinical situation modify treatment. Exclusive transfusion of platelet concentrates may be inappropriate as potentially adverse effects can outweigh its benefit. A stepwise and individually adjusted approach for restitution and maintenance of haemostasis is recommended. Administration of antifibrinolytics is generally endorsed, but is of particular use in Quebec disease. Restricted to older children, desmopressin is favourable in storage pool disease and unclassified platelet disorders. Although licensed only for patients with Glanzmann thrombasthenia and alloantibodies, in clinical practice rFVIIa is widely used in inherited platelet disorders with severe bleeding tendency. This guideline aims at presenting the best available advice for the management of patients with inherited platelet function disorders.

Pharmacokinetics of ε-Aminocaproic Acid in Neonates Undergoing Cardiac Surgery with Cardiopulmonary Bypass

BACKGROUND

Antifibrinolytic medications such as ε-aminocaproic acid (EACA) are used in pediatric heart surgery to decrease surgical bleeding and transfusion. Dosing schemes for neonates are often based on adult regimens, or are simply empiric, in part due to the lack of neonatal pharmacokinetic information. The authors sought to determine the pharmacokinetics of EACA in neonates undergoing cardiac surgery and to devise a dosing regimen for this population.

METHODS

Ten neonates undergoing cardiac surgery with cardiopulmonary bypass were given EACA according to standard practice, and blood was drawn at 10 time points to determine drug concentrations. Time-concentration profiles were analyzed using nonlinear mixed effects models. Parameter estimates (standardized to a 70-kg person) were used to develop a dosing regimen intended to maintain a target concentration shown to inhibit fibrinolysis in neonatal plasma (50 mg/l).

RESULTS

Pharmacokinetics were described using a two-compartment model plus an additional compartment for the cardiopulmonary bypass pump. First-order elimination was described with a clearance of 5.07 l/h × (WT/70). Simulation showed a dosing regimen with a loading dose of 40 mg/kg and an infusion of 30 mg · kg · h, with a pump prime concentration of 100 mg/l maintained plasma concentrations above 50 mg/l in 90% of neonates during cardiopulmonary bypass surgery.

CONCLUSIONS

EACA clearance, expressed using allometry, is reduced in neonates compared with older children and adults. Loading dose and infusion dose are approximately half those required in children and adults.

Antifibrinolytic Therapy for Cardiac Surgery

Antifibrinolytic therapy reduces bleeding and chest tube drainage output in cardiac surgical patients but is associated with potential side effects. Two phase-II studies with new compounds were terminated prematurely. There is increasing evidence of adverse side effects with tranexamic acid.

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.

Tranexamic acid administration to pediatric trauma patients in a combat setting: the pediatric trauma and tranexamic acid study (PED-TRAX)

BACKGROUND

Early administration of tranexamic acid (TXA) has been associated with a reduction in mortality and blood product requirements in severely injured adults. It has also shown significantly reduced blood loss and transfusion requirements in major elective pediatric surgery, but no published data have examined the use of TXA in pediatric trauma.

METHODS

This is a retrospective review of all pediatric trauma admissions to the North Atlantic Treaty Organization Role 3 hospital, Camp Bastion, Afghanistan, from 2008 to 2012. Univariate and logistic regression analyses of all patients and select subgroups were performed to identify factors associated with TXA use and mortality. Standard adult dosing of TXA was used in all patients.

RESULTS

There were 766 injured patients 18 years or younger (mean [SD] age, 11 [5] years; 88% male; 73% penetrating injury; mean [SD], Injury Severity Score [ISS], 10 [9]; mean [SD] Glasgow Coma Scale [GCS] score, 12 [4]). Of these patients, 35% required transfusion in the first 24 hours, 10% received massive transfusion, and 76% required surgery. Overall mortality was 9%. Of the 766 patients, 66 (9%) received TXA. The only independent predictors of TXA use were severe abdominal or extremity injury (Abbreviated Injury Scale [AIS] score ≥ 3) and a base deficit of greater than 5 (all p < 0.05). Patients who received TXA had greater injury severity, hypotension, acidosis, and coagulopathy versus the patients in the no-TXA group. After correction for demographics, injury type and severity, vitals, and laboratory parameters, TXA use was independently associated with decreased mortality among all patients (odds ratio, 0.3; p = 0.03) and showed similar trends for subgroups of severely injured (ISS > 15) and transfused patients. There was no significant difference in thromboembolic complications or other cardiovascular events. Propensity analysis confirmed the TXA-associated survival advantage and suggested significant improvements in discharge neurologic status as well as decreased ventilator dependence.

CONCLUSION

TXA was used in approximately 10% of pediatric combat trauma patients, typically in the setting of severe abdominal or extremity trauma and metabolic acidosis. TXA administration was independently associated with decreased mortality. There were no adverse safety- or medication-related complications identified.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Continuous or discontinuous tranexamic acid effectively inhibits fibrinolysis in children undergoing cardiac surgery with cardiopulmonary bypass

Tranexamic acid is given continuously or discontinuously as an anti-fibrinolytic therapy during cardiac surgery, but the effects on fibrinolysis parameters remain poorly investigated. We sought to assess the effects of continuous and discontinuous tranexamic acid on fibrinolysis parameters in children undergoing cardiac surgery with cardiopulmonary bypass (CPB). Children requiring cardiac surgery or repeat surgery by sternotomy with CPB for congenital heart disease were randomized to receive either continuous or discontinuous tranexamic acid. Blood tranexamic acid, D-dimers, tissue plasminogen activator (tPA), tPA-plasminogen activator inhibitor 1 (tPA-PAI1) complexes, fibrinogen and fibrin monomers were measured and compared to values obtained from children who did not receive tranexamic acid. Tranexamic acid inhibited the CPB-induced increase in D-dimers, with a similar potency between continuous and discontinuous regimens. Time courses for tPA, fibrin monomers, and fibrinogen were also similar for both regimen, and there was a significant difference in tPA-PAI1 complex concentrations at the end of surgery, which may be related to a significantly higher tranexamic acid concentration. Continuous and discontinuous regimen are suitable for an effective inhibition of fibrinolysis in children undergoing cardiac surgery with CPB, but the continuous regimen was previously shown to be more effective to maintain stable tranexamic acid concentrations.

Tranexamic acid--an old drug still going strong and making a revival

Experience with tranexamic acid, an indirect fibrinolytic inhibitor, started as soon as it was released from Shosuke Okamoto's lab in the early 1960s. It was first prescribed to females with heavy menstrual blood loss and to patients with hereditary bleeding disorders. Soon the indications were widened to elective surgery because of its blood saving effects. Contraindications are few, most important is ongoing venous or arterial thrombosis and allergy to tranexamic acid, and the doses has to be reduced in renal insufficiency. In randomized controlled trials, however, patients with other risk factors are excluded as well (patients with history of cardiovascular disease, thromboembolism, bleeding diathesis, renal failure with creatinine >250μmol/L, pregnancy, and patients on treatment with anticoagulants). Recent meta-analyses of several randomized controlled trials in orthopedic arthroplasty have shown that tranexamic acid reduces peri- and postoperative blood loss, blood transfusion requirements and reoperations caused by bleedings. In general, the preoperative dose was 10-15mg/kg i.v. (or 1g), followed or not, by one or two doses, some as continuous infusion i.v. To validate relationship between dose and effect more data are needed. No evidence was found of increased thromboembolic accidents or other adverse events in the patients on tranexamic acid compared to the control groups. In major cardiac surgery tranexamic acid has been used in a large number of controlled trials with various dosing schemes in which the highest dosages seem to be associated with neurotoxicity; therefore a maximum total dose of 100mg/kg especially in patients over 50years of age is recommended by ISMICS (International Society for Minimally Invasive Cardiothoracic Surgery). Other indications for tranexamic acid are reviewed here as well. In recent years the extensive trial in severe trauma with massive bleedings using tranexamic acid was presented, CRASH-2 (Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage) comprising more than 20,000 patients. It showed that the survival was increased when tranexamic acid was given early after the accident compared to placebo; further studies are taking place is this field to get more information. Of utmost importance is the ongoing WOMAN (World Maternal Antifibrinolytic) a randomized, double-blind, placebo controlled trial among 15,000 with clinical diagnosis of postpartum haemorrhage bearing in mind that each year a large number of women in low and middle income countries, die from causes related to childbirth. In summary, we consider tranexamic acid is a drug of great value to reduce almost any kind of bleeding, it is cheap and convenient to use and has principally few contraindications. It may be added, that tranexamic acid is included in the WHOs list of essential medicines.

[Efficacy and safety of tranexamic acid administration for the prevention and/or the treatment of post-partum haemorrhage: a systematic review with meta-analysis]

OBJECTIVE(S)

Assess the efficacy and safety of tranexamic acid administration for the prevention and/or the treatment of postpartum haemorrhage.

STUDY DESIGN

Systematic review with meta-analysis.

MATERIAL AND METHODS

Systematic review of the literature with the aim of identifying prospective, randomised, controlled trials that assessed the effect of tranexamic acid on peripartum blood loss and transfusion requirement in three clinical contexts: (i) prevention of post-partum haemorrhage in case of elective caesarean section, (ii) prevention of post-partum haemorrhage in case of vaginal delivery, (iii) treatment of post-partum haemorrhage.

RESULTS

Prophylactic administration of tranexamic acid reduced blood loss (mean difference for intraoperative blood loss: -177.9mL, IC 95%: -189.51 to -166.35, total blood loss: -183.94, IC 95%: -198.29 to -169.60), and the incidence of severe post-partum haemorrhage (OR: 0.49, IC 95%: 0.33 to 0.74). None of the published trials assessed the effect of tranexamic acid on blood products administration or transfusion requirement. Only one study assessed and reported the efficacy of tranexamic acid when administered as a treatment for postpartum haemorrhage. A significant reduction in blood loss was reported within 30 minutes after randomisation (P=0.03) and confirmed after 6 hours (median: 170mL (58-323) vs 221mL (110-543), P=0.04). None of the included studies adequately studied the incidence of side effects after tranexamic acid administration.

CONCLUSION

Although tranexamic acid administration seemed to significantly reduce blood loss and the incidence of severe post-partum haemorrhage, further prospective trials are needed to confirm the efficacy and safety of tranexamic administration in the treatment of postpartum haemorrhage. Those studies should assess the pharmacokinetic profile and the safety of this drug in pregnant women.

Tranexamic acid in pediatric trauma: why not?

Trauma is a leading cause of death in pediatrics. Currently, no medical treatment exists to reduce mortality in the setting of pediatric trauma; however, this evidence does exist in adults. Bleeding and coagulopathy after trauma increases mortality in both adults and children. Clinical research has demonstrated a reduction in mortality with early use of tranexamic acid in adult trauma patients in both civilian and military settings. Tranexamic acid used in the perioperative setting safely reduces transfusion requirements in children. This article compares the hematologic response to trauma between children and adults, and explores the potential use of tranexamic acid in pediatric hemorrhagic trauma.