Developmental hemostasis: clinical implications from the fetus to the adolescent

Factors Affecting the Discrepancy Between Coagulation Times on Extracorporeal Circulation Using Unfractionated Heparin in Children and Young Adults

In unfractionated heparin (UFH) monitoring during extracorporeal circulation, the traditional measures of activated clotting time (ACT) or activated partial thromboplastin time (APTT) may diverge, confounding anticoagulant adjustments. We aimed to explore the factors explaining this discrepancy in children and young adults. This retrospective observational study, conducted at an urban regional tertiary hospital, included consecutive pediatric patients who received UFH during extracorporeal circulation (continuous kidney replacement therapy or extracorporeal membrane oxygenation) between April 2017 and March 2021. After patients whose ACT and APTT were not measured simultaneously or who were also taking other anticoagulants were excluded, we analyzed 94 samples from 23 patients. To explain the discrepancy between ACT and APTT, regression equations were created using a generalized linear model (family  =  gamma, link  =  logarithmic) with ACT as the response variable. Other explanatory variables included age, platelet count, and antithrombin. Compared to APTT alone as an explanatory variable, the Akaike information criterion and pseudo-coefficient of determination improved from 855 to 625 and from 0.01 to 0.42, respectively, when these explanatory variables were used. In conclusion, we identified several factors that may explain some of the discrepancy between ACT and APTT in the routinely measured tests. Evaluation of these factors may aid in appropriate adjustments in anticoagulation therapy.

Longitudinal observations of TFPI levels in paediatric Haemophilia A patients

INTRODUCTION

Inhibition of tissue factor pathway inhibitor (TFPI) is a potential new mode of action to achieve haemostasis in haemophilia A and B patients.

AIM

Knowledge about potential developmental changes of TFPI levels during childhood are a prerequisite to translate adult doses of TFPI inhibitors to doses in paediatric patients.

METHODS

In this study we present longitudinal data for total TFPI concentrations (TFPI-T) and TFPI activity (TFPI-A) from 48 paediatric Haemophilia A patients in the age range from 3 to 18 years (2-12 observations per patient).

RESULTS

TFPI-T and TFPI-A tend to decrease over age during childhood. Lowest values were observed between 12 and <18 years. On average, TFPI-T and TFPI-A were lower in adolescent haemophilia patients than in adult haemophilia patients.

CONCLUSION

In summary, the presented information on TFPI levels in children adds to the current knowledge of developmental haemostasis and it can be helpful in evaluating how children respond to haemophilia treatment including the new class of anti-TFPI compounds.

The Utility of NATEM Assay in Predicting Bleeding Risk in Critically Ill Neonates

We aimed to investigate the hemostatic status of diseased neonates using nonactivated rotational thromboelastometry (ROTEM) assay (NATEM) assay and, in addition, to evaluate the discriminative power of NATEM parameters in predicting the risk of bleeding in critically ill neonates and compare it to that of EXTEM (extrinsically activated ROTEM) parameters. This cohort study included 158 consecutive, critically ill neonates with presumed sepsis, perinatal hypoxia, or respiratory distress syndrome. The EXTEM and NATEM assays were performed on the first day of disease onset. The neonatal bleeding assessment tool was used to record and assess clinical bleeding events on the day of ROTEM analysis. Several EXTEM and NATEM ROTEM parameters differed between neonates with and without clinical bleeding events, indicating a hypo-coagulable state in neonates with clinical bleeding. NATEM parameters had comparable predictive performance for clinical bleeding events with EXTEM parameters for clotting time, clot formation time (CFT), A10 (clot amplitude at 10minutes), maximum clot firmness, lysis index at 60minutes, and maximum clot elasticity (p>0.05). However, NATEM A20, A30, and α angle demonstrated better predictive ability than EXTEM A20, A30, and α angle, respectively (p<0.05). A NATEM CFT value ≥147seconds presented 95.2% sensitivity (95% confidence interval [CI]: 76.1-99.8%) and 65.6% specificity (95% CI: 57.1-73.5%) to detect neonates with clinical bleeding, while a NATEM A10 value ≤42mm had 80.8% sensitivity (95% CI: 71.8-85.9%) and 76.0% specificity (95% CI: 52.8-91.7%) to detect neonates with clinical bleeding events. The NATEM assay has shown remarkable sensitivity in predicting bleeding in critically ill neonates, exceeding EXTEM performance in some selected parameters. The incorporation of NATEM test parameters in predictive models for neonatal hemorrhage seems promising.

Non-criteria antiphospholipid antibodies and pediatric rheumatic disease: a case series

BACKGROUND

Non-criteria antiphospholipid antibodies (NC-aPL) are a relatively undefined subgroup of antiphospholipid antibodies (aPL). Knowledge about NC-aPL in adults is limited and even less is known in pediatric patients. Routine tests for antiphospholipid syndrome (APS)-a clinical state marked by the presence of aPL in association with vascular thrombosis-usually include lupus anticoagulant (LAC), anti-cardiolipin (aCL) and -beta-2 glycoprotein I (aβ2GPI). LAC is a functional screen for prothrombotic aPL, while the latter tests identify specific autoantibodies. Specific targets of NC-aPL include, but are not limited to, phosphatidylethanolamine, phosphatidylserine, and prothrombin.

PRESENTATION OF CASES

We present single-center data from eight pediatric patients with NC-aPL identified during a three-year period. All patients had presenting features raising suspicion for APS. Most patients were female with a primary rheumatic disease. One patient had a stroke. Another patient had alveolar hemorrhage and pulmonary hypertension. Raynaud's phenomenon, rashes involving distal extremities, and headaches were common. Most patients had a positive LAC, yet their routine aPL tests were negative, prompting testing for NC-aPL.

CONCLUSIONS

Our findings suggest NC-aPL are associated with typical signs and symptoms of APS in pediatric patients. Pediatricians and pediatric subspecialists should consider NC-aPL when clinical suspicion is high and routine aPL tests are negative, particularly when LAC is positive. While guidelines for NC-aPL do not yet exist for children or adults, these autoantibodies have pathogenic potential. Actionable items could include evaluation for the presence of other (primary) rheumatic diseases, and consultation with hematologists and/or obstetricians regarding anticoagulation/platelet inhibition and thrombosis education. Future guidelines regarding NC-aPL will only be generated by gathering more data, ideally prospectively.

The Vascular Endothelium and Coagulation: Homeostasis, Disease, and Treatment, with a Focus on the Von Willebrand Factor and Factors VIII and V

The vascular endothelium has several important functions, including hemostasis. The homeostasis of hemostasis is based on a fine balance between procoagulant and anticoagulant proteins and between fibrinolytic and antifibrinolytic ones. Coagulopathies are characterized by a mutation-induced alteration of the function of certain coagulation factors or by a disturbed balance between the mechanisms responsible for regulating coagulation. Homeostatic therapies consist in replacement and nonreplacement treatments or in the administration of antifibrinolytic agents. Rebalancing products reestablish hemostasis by inhibiting natural anticoagulant pathways. These agents include monoclonal antibodies, such as concizumab and marstacimab, which target the tissue factor pathway inhibitor; interfering RNA therapies, such as fitusiran, which targets antithrombin III; and protease inhibitors, such as serpinPC, which targets active protein C. In cases of thrombophilia (deficiency of protein C, protein S, or factor V Leiden), treatment may consist in direct oral anticoagulants, replacement therapy (plasma or recombinant ADAMTS13) in cases of a congenital deficiency of ADAMTS13, or immunomodulators (prednisone) if the thrombophilia is autoimmune. Monoclonal-antibody-based anti-vWF immunotherapy (caplacizumab) is used in the context of severe thrombophilia, regardless of the cause of the disorder. In cases of disseminated intravascular coagulation, the treatment of choice consists in administration of antifibrinolytics, all-trans-retinoic acid, and recombinant soluble human thrombomodulin.

COVID-19 Infection in Children and Infants: Current Status on Therapies and Vaccines

Since the beginning in December 2019, the SARS-CoV-2 outbreak appeared to affect mostly the adult population, sparing the vast majority of children who only showed mild symptoms. The purpose of this investigation is to assess the status on the mechanisms that give children and infants this variation in epidemiology compared to the adult population and its impact on therapies and vaccines that are aimed towards them. A literature review, including in vitro studies, reviews, published guidelines and clinical trials was performed. Clinical trials concerned topics that allowed a descriptive synthesis to be produced. Four underlying mechanisms were found that may play a key role in providing COVID-19 protection in babies. No guidelines are available yet for therapy due to insufficient data; support therapy remains the most used. Only two vaccines are approved by the World Health Organization to be used in children from 12 years of age, and there are currently no efficacy or safety data for children below the age of 12 years. The COVID-19 clinical frame infection is milder in children and adolescents. This section of the population can act as vectors and reservoirs and play a key role in the transmission of the infection; therefore, vaccines are paramount. More evidence is required to guide safely the vaccination campaign.

Developmental Hemostasis: The Evolution of our Coagulation System

Developmental hemostasis describes the evolution of the coagulation system from the neonatal period through adulthood. Neonates have lower levels of coagulation factors and elevated screening levels at birth. These levels can be influenced by various circumstances including gestational age, labor effects, and clinical status. The most commonly used screening tests for coagulopathy are the prothrombin time, partial thromboplastin time, and fibrinogen level. These values can be difficult to interpret as every laboratory has its own age-specific reference ranges. An understanding of developmental hemostasis is important when evaluating, diagnosing, and treating clinical manifestations, including vitamin K deficiency, surgical needs, infections, inherited thrombophilias, and inherited bleeding disorders. The mainstay of treatment for bleeding or hemorrhage is platelet and fresh frozen plasma transfusions. For the treatment of thrombosis, unfractionated heparin and low-molecular-weight heparin are the 2 most commonly used anticoagulants in the neonatal setting.

Predictors of venous thromboembolism among infants in children's hospitals in the United States: a retrospective Pediatric Health Information Study

OBJECTIVES

Examine: (1) Prevalence of diagnosed venous thromboembolism (VTE) in infants <6 months discharged from U.S. NICUs; (2) Associations between sociodemographic and clinical factors and VTE; (3) Secondary outcomes related to VTE.

STUDY DESIGN

Multivariable logistic regressions examined associations between VTE and sociodemographic and clinical factors among infants <6 months discharged from Pediatric Health Information System (PHIS) NICUs between 2016 and 2019.

RESULTS

Of 201,033 infants, 2720 (1.35%) had diagnosed VTE. Birthweight 300-1000 g (aOR 3.14, 95% CI 2.54-3.88), 1000-1500 g (aOR 1.77, 95% CI 1.40-2.42) versus 2500-3999 g, and public (aOR 1.18, 95% CI 1.02-1.37) versus private insurance were associated with increased odds of VTE, as were CVC, TPN, mechanical ventilation, infection, ECMO, and surgery. All types of central lines (non-tunneled and tunneled CVCs, PICCs, and umbilical catheters) had higher odds of VTE than not having that type of line. CVCs in upper versus lower extremities had higher odds of VTE.

CONCLUSION

Infants with risk factors may require monitoring for VTE. Results may inform VTE prevention.

Developmental hemostasis in the neonatal period

BACKGROUND

The hemostatic system is complex and evolves continuously since gestation and well into the adult years, in a process known as "developmental hemostasis."

DATA SOURCES

A comprehensive review was performed after an extensive literature search on PubMed/MEDLINE concerning developmental hemostasis during the neonatal period. Relevant cross references were also included.

RESULTS

Although part of a system, each component of the hemostatic system evolves differently, with many displaying both quantitative and qualitative age-related differences. This leads to drastic disparities between the coagulation system of neonates and both other children's and adults', while still maintaining a generally balanced and physiological hemostasis. The motives behind this process remain to be fully elucidated but may be, at least in part, related to non-hemostatic factors.

CONCLUSIONS

Knowledge regarding "developmental hemostasis" is essential for everyone caring for newborns or even children in general and in this review, we describe each hemostatic system component's neonatal characteristics and age-related progression as well as explore some of the possible physiological motives behind the process.

Endothelial dysfunction in preterm infants: The hidden legacy of uteroplacental pathologies

Millions of infants are born prematurely every year worldwide. Prematurity, particularly at lower gestational ages, is associated with high mortality and morbidity and is a significant global health burden. Pregnancy complications and preterm birth syndrome strongly impact neonatal clinical phenotypes and outcomes. The vascular endothelium is a pivotal regulator of fetal growth and development. In recent years, the key role of uteroplacental pathologies impairing endothelial homeostasis is emerging. Conditions leading to very and extremely preterm birth can be classified into two main pathophysiological patterns or endotypes: infection/inflammation and dysfunctional placentation. The first is frequently related to chorioamnionitis, whereas the second is commonly associated with hypertensive disorders of pregnancy and fetal growth restriction. The nature, timing, and extent of prenatal noxa may alter fetal and neonatal endothelial phenotype and functions. Changes in the luminal surface, oxidative stress, growth factors imbalance, and dysregulation of permeability and vascular tone are the leading causes of endothelial dysfunction in preterm infants. However, the available evidence regarding endothelial physiology and damage is limited in neonates compared to adults. Herein, we discuss the current knowledge on endothelial dysfunction in the infectious/inflammatory and dysfunctional placentation endotypes of prematurity, summarizing their molecular features, available biomarkers, and clinical impact. Furthermore, knowledge gaps, shadows, and future research perspectives are highlighted.

Hemostatic Evaluation With Viscoelastic Coagulation Monitor: A Nicu Experience

BACKGROUND

Viscoelastic coagulation tests provide valuable information in neonatal intensive care units (NICUs), but the lack of reference intervals still limits their decision-making power according to gestational age. The aim of the present study is to evaluate the hemostasis of a cohort of full-term (FT) and late-preterm (LP) infants using the viscoelastic coagulation monitor (VCM®) system, a new portable device that uses untreated whole blood.

METHODS

An observational study was performed to identify non-coagulopathic FT and LP infants admitted to III° level NICU (January 2020 to December 2021) with a VCM test in the first 72 h of life.

RESULTS

Forty-five patients were enrolled, 26 FT and 19 LP. No statistical differences in hemostatic parameters were observed between FT and LP nor between stable and unstable neonates. Clotting time (CT) was positive correlated with PT (p = 0.032), not with aPTT (p = 0.185). From linear regression, platelet resulted associated with: clot formation time (CTF, p = 0.003), alpha angle (Alpha, p = 0.010), amplitude at 10 (A10, p = 0.001), amplitude at 20 min (A20, p < 0.001), maximum clot firmness (MCF, p < 0.001); and fibrinogen was associated with: A10 (p = 0.008), A20 (p = 0.015) and MCF (p = 0.024). Compared to the adult reference population, neonates showed shorter CT (mean (SD): 5.3 (1.4) vs. 7.0 (0.9) min, p < 0.001), CFT (2.4 (0.7) vs. 2.8 (0.6) minutes, p < 0.001) and higher Alpha (60.8 (6.3) vs. 55 (5)°, p < 0.001). In addition, the neonatal cohort showed an early transient difference in amplitude and fibrinolysis, as follows: A10 (28.0 (5.0) vs. 26 (4) VCM units, p =0.004), A20 (34.8 (5.0) vs. 33 (4) VCM units, p =0.012), and LI30 (99.8 (0.5) vs. 99 (1)%, p <0.001).

CONCLUSIONS

The viscoelastic profile of FT and LP infants assessed with VCM showed a hemostatic competence characterized by accelerated coagulation and clot formation time, in line with other viscoelastic techniques. VCM system provides promising applications in the NICU setting.

COVID-19 Infection in Children, Infants and Pregnant Subjects: An Overview of Recent Insights and Therapies

BACKGROUND

The SARS-CoV-2 pandemic has involved a severe increase of cases worldwide in a wide range of populations. The aim of the present investigation was to evaluate recent insights about COVID-19 infection in children, infants and pregnant subjects.

METHODS

a literature overview was performed including clinical trials, in vitro studies, reviews and published guidelines regarding the present paper topic. A descriptive synthesis was performed to evaluate recent insights and the effectiveness of therapies for SARS-CoV-2 infection in children, infants and pregnant subjects.

RESULTS

Insufficient data are available regarding the relationship between COVID-19 and the clinical risk of spontaneous abortion and premature foetus death. A decrease in the incidence of COVID-19 could be correlated to a minor expression of ACE2 in childrens' lungs. At present, a modulation of the dose-effect posology for children and infants is necessary.

CONCLUSIONS

Pregnant vertical transmission has been hypothesised for SARS-CoV-2 infection. Vaccines are necessary to achieve mass immunity for children and also pregnant subjects.

SARS-CoV-2 infection in the immunodeficient host: necessary and dispensable immune pathways

Since its outbreak in late December 2019 in Wuhan, coronavirus disease 2019 pandemic has posed a therapeutic challenge for the world population, with a plenty of clinical pictures and a broad spectrum of severity of the manifestations. In spite of initial speculations on a direct role of primary or acquired immune deficiency in determining a worse disease outcome, recent studies have provided evidence that specific immune defects may either serve as an experimentum naturae entailing this risk or may not be relevant enough to impact the host defense against the virus. Taken together, these observations may help unveil pathogenetic mechanisms of the infection and suggest new therapeutic strategies. Thus, in this review, we summarize current knowledge regarding the mechanisms of immune response against severe acute respiratory syndrome coronavirus 2 infection and clinical manifestations with a special focus on children and patients presenting with congenital or acquired immune deficiency.

Thrombosis in infants in the neonatal intensive care unit: Analysis of a large national database

BACKGROUND

Thrombosis in the neonatal population is rare, but increasing. Its incidence and management are not well understood.

OBJECTIVES

To investigate the incidence, associated factors, and management of thrombosis in the neonatal intensive care unit (NICU) population.

PATIENTS/METHODS

We performed a retrospective cohort study of infants admitted to a Pediatrix Medical Group-affiliated NICU from 1997 through 2015. We determined the prevalence of venous and arterial thrombosis, and assessed demographic characteristics and known risk factors. Categorical variables were compared with the Pearson χ2 test and continuous variables with Wilcoxon rank-sum tests. Stepwise logistic regression was used to identify associated factors. The primary outcome was incidence of thrombosis. Secondary analyses investigated correlations between clinical and demographic characteristics and thrombosis.

RESULTS

Among 1 158 755 infants, we identified 2367 (0.20%) diagnosed with thrombosis. In a multivariable regression analysis, prematurity, male sex, congenital heart disease, sepsis, ventilator support, vasopressor receipt, central venous catheter, invasive procedures, and receipt of erythropoietin were associated with increased risk of thrombosis, while Black race and Hispanic ethnicity were associated with reduced risk. The majority of infants diagnosed with thrombosis (73%) received no anticoagulation, but anticoagulant use in infants with thrombosis was higher than those without (27% versus 0.2%, P < .001). Thrombosis in infants was associated with higher mortality (11% versus 2%, P < .001) and longer hospital stays (57 days, [interquartile range (IQR) 28--100] versus 10 days, [IQR 6--22], P < .001).

CONCLUSIONS

In the largest national study to date, we found that thrombosis in NICU patients is associated with prematurity, low birth weight, sepsis, and invasive procedures.

Congenital Hypofibrinogenemia: Presentation of a Rare Coagulation Disorder

Fibrinogen is a precursor of fibrin, which acts as a procoagulant plasma soluble protein. It is involved in blood viscosity and clot stability to help in the recovery of damaged blood vessels. We describe the case of a preterm newborn who presented with abdominal distension and manifestations of bleeding in venipuncture sites. In the initial laboratories, prolonged coagulation times were observed with a decreased concentration of fibrinogen. This newborn had transfusion support, with recovery in factor levels and a subsequent decrease in them. Based on this trend and ruling out other possible causes of hypofibrinogenemia, such as liver disease, sepsis, or disseminated intravascular coagulation, the diagnosis of congenital hypofibrinogenemia was made. This case report includes the diagnostic and therapeutic approach of an unusual hemorrhagic presentation in the newborn, highlighting the need for transfusion and dynamic fibrinogen replacement to prevent complications and seek rapid improvement in symptoms.

Treatment of children with COVID-19: position paper of the Italian Society of Pediatric Infectious Disease

A statement of consensus was formulated after reviewing available literature on pediatric treatment strategies for COVID-19 by the Steering and Scientific Committee of the Italian Society of Infectious Pediatric Diseases in connection with the Italian Society of Paediatrics.

Correlation Among Antifactor Xa, Activated Partial Thromboplastin Time, and Heparin Dose and Association with Pediatric Extracorporeal Membrane Oxygenation Complications

Anticoagulation is essential during extracorporeal membrane oxygenation (ECMO) to prevent catastrophic circuit clotting. Several assays exist to monitor unfractionated heparin (UFH), the most commonly used anticoagulant during ECMO, but no single test or combination of tests has consistently been proven to be superior. This retrospective observational study examines the correlation among antifactor Xa level, activated partial thromboplastin time (aPTT), and UFH dose and the association between antifactor Xa level and aPTT with survival and hemorrhagic and thrombotic complications. Sixty-nine consecutive neonatal and pediatric ECMO patients from September 2012 to December 2014 at a single institution were included. Spearman rank correlation was used to compare antifactor Xa level, aPTT, and UFH dose. Significant but poor correlation exists between antifactor Xa level and UFH dose ρ = 0.1 (p < 0.0001) and aPTT and UFH dose ρ = 0.26 (p < 0.0001). Antifactor Xa level and aPTT were weakly correlated to each other ρ = 0.38 (p < 0.0001). In an univariate analysis, there was no difference between survival and antifactor Xa level, aPTT, or UFH dose. Multiple anticoagulation tests may be superior to a single test during ECMO.

The Developing Balance of Thrombosis and Hemorrhage in Pediatric Surgery: Clinical Implications of Age-Related Changes in Hemostasis

Bleeding and thrombosis in critically ill infants and children is a vexing clinical problem. Despite the relatively low incidence of bleeding and thrombosis in the overall pediatric population relative to adults, these critically ill children face unique challenges to hemostasis due to extreme physiologic derangements, exposure of blood to foreign surfaces and membranes, and major vascular endothelial injury or disruption. Caring for pediatric patients on extracorporeal support, recovering from solid organ transplant or invasive surgery, and after major trauma is often complicated by major bleeding or clotting events. As our ability to care for the youngest and sickest of these children increases, the gaps in our understanding of the clinical implications of developmental hemostasis have become increasingly important. We review the current understanding of the development and function of the hemostatic system, including the complex and overlapping interactions of coagulation proteins, platelets, fibrinolysis, and immune mediators from the neonatal period through early childhood and to young adulthood. We then examine scenarios in which our ability to effectively measure and treat coagulation derangements in pediatric patients is limited. In these clinical situations, adult therapies are often extrapolated for use in children without taking age-related differences in pediatric hemostasis into account, leaving clinicians confused and impacting patient outcomes. We discuss the limitations of current coagulation testing in pediatric patients before turning to emerging ideas in the measurement and management of pediatric bleeding and thrombosis. Finally, we highlight opportunities for future research which take into account this developing balance of bleeding and thrombosis in our youngest patients.

Venous thromboembolism in childhood: where is Brazil after 20 years?

Due to the longer survival of critically ill children, venous thromboembolism is a problem which is becoming increasingly recognized in pediatric practice. In the last decades, several international studies have been published, shedding a light upon the epidemiology of this disease during childhood. These data show peculiarities in the clinical presentation and the significant morbidity and mortality. The new "epidemic of thrombosis" in pediatric hospitals points toward the urgent need for specific treatment and prevention protocols targeting this population. In Brazil, knowledge regarding this disease remains scarce. The lack of epidemiological data impacts both the clinical care and the design of specific public policies in the field. Thus, a national registry of pediatric venous thromboembolism is relevant to the proposal of an appropriate plan of action to create a qualified net of assistance. The improvement in educational initiatives related to the field of Pediatric Hemostasis is also very important. In this review, we have updated the epidemiological, clinical and therapeutic aspects of the disease, as well as the prevention strategies.

Establishing a reference range for thromboelastograph parameters in the neonatal period

Introduction

Acquired coagulation disorders are a common cause of neonatal bleeding. The thromboelastograph (TEG) comprehensively assesses haemostatic processes in the body. Unfortunately, the reference range of TEG parameters in the neonatal period has not yet been evaluated, which limits the use of the TEG in neonates. In this study, we aimed to establish the reference range of TEG parameters for the neonatal period.

Methods

This study included 371 full‐term infants (≥37 weeks of gestation), and we divided these infants into three groups according to age as follows: 1, 2‐7 and 8‐28 days. We measured their peripheral blood using TEG, coagulation routine and platelet count tests. We analysed differences among the groups.

Results

The reference ranges for TEG parameters are presented as medians and reference ranges (2.5th and 97.5th percentiles) as follows: R (clot reaction time, seconds) 4.80 (2.80‐7.17), Angle (fibrin production rate) 69.90 (44.91‐78.89), K (clot kinetics, min) 1.40 (0.80‐4.50), MA (maximum amplitude, mm) 63.50(44.34‐74.66) and LY30 (lysis at 30 minutes, %) 0.10 (0.10‐6.95). There were significant differences in Angle, K, MA and LY30 values between the different neonatal day age groups.

Conclusion

This study preliminarily establishes a reference range for TEG parameters during the neonatal period. The age of a newborn had a large influence on TEG parameters. Additionally, we demonstrated a correlation between laboratory tests and TEG parameters for this age period. The reference values provided herein are meaningful for future studies.

Antithrombin deficiency is associated with mortality and impaired organ function in septic pediatric patients: a retrospective study

Background

Sepsis remains a major problem in intensive care medicine. It is often accompanied by coagulopathies, leading to thrombotic occlusion of small vessels with subsequent organ damage and even fatal multi-organ failure. Prediction of the clinical course and outcome—especially in the heterogeneous group of pediatric patients—is difficult. Antithrombin, as an endogenous anticoagulant enzyme with anti-inflammatory properties, plays a central role in controling coagulation and infections. We investigated the relationship between antithrombin levels and organ failure as well as mortality in pediatric patients with sepsis.

Methods

Data from 164 patients under the age of 18, diagnosed with sepsis, were retrospectively reviewed. Antithrombin levels were recorded three days before to three days after peak C-reactive protein to correlate antithrombin levels with inflammatory activity. Using the concept of developmental haemostasis, patients were divided into groups <1 yr and ≥1 yr of age.

Results

In both age groups, survivors had significantly higher levels of antithrombin than did deceased patients. An optimal threshold level for antithrombin was calculated by ROC analysis for survival: 41.5% (<1 yr) and 67.5% (≥1 yr). The mortality rate above this level was 3.3% (<1 yr) and 9.5% (≥1 yr), and below this level 41.7% (<1 yr) and 32.2% (≥1 yr); OR 18.8 (1.74 to 1005.02), p = 0.0047, and OR 4.46 (1.54 to 14.89), p = 0.003. In children <1 yr with antithrombin levels <41.5% the rate of respiratory failure (66.7%) was significantly higher than in patients with antithrombin levels above this threshold level (23.3%), OR 6.23 (1.23 to 37.81), p = 0.0132. In children ≥1 yr, both liver failure (20.3% vs 1.6%, OR 15.55 (2.16 to 685.01), p = 0.0008) and a dysfunctional intestinal tract (16.9% vs 4.8%, OR 4.04 (0.97 to 24.08), p = 0.0395) occurred more frequently above the antithrombin threshold level of 67.5%.

Conclusion

In pediatric septic patients, significantly increased mortality and levels of organ failure were found below an age-dependent antithrombin threshold level. Antithrombin could be useful as a prognostic marker for survival and occurrence of organ failure in pediatric sepsis.

Thrombotic and hemorrhagic complications in children and young adult recipients of Hematopoietic Stem Cell Transplant (HSCT)

BACKGROUND

Overall incidence of hemostatic complications in pediatric recipients of Hematopoietic Stem Cell Transplant (HSCT) is scarcely studied. This retrospective review explored the incidence and underlying risk factors of bleeding and thrombotic complications in children.

PROCEDURE

Clinical characteristics, hemorrhagic events (HE), thrombotic events (TE) and follow up data were abstracted from medical records on patients aged <21 years undergoing HSCT during January 2000-June 2015.

RESULTS

From start of conditioning until last follow up, 238 pediatric patients were reviewed during this study. There were 16 symptomatic thrombotic complications in 15 patients, along with 13 major bleeding events. Incidence of HE or TE was higher in allogeneic HSCT compared to autologous HSCT (p = 0.02). Severe thrombocytopenia could not be identified as a major contributor to bleeding. All patients with HE had platelets between 20,000-50,000 × 10⁹/L, except one patient, who had platelets <20,000 × 10⁹/L. All patients with hemorrhagic cystitis (n = 7) had received cyclophosphamide (Cy). For patients with sinusoidal obstruction syndrome, conditioning included either busulfan (Bu)/Cy (n = 5), Cy with total body irradiation (n = 4), or thiotepa (n = 2). Among allogeneic HSCT recipients, 60% of HE and 92% with TE had underlying myeloid neoplasms. Graft versus Host disease contributed to both types of complications (p = 0.07), although not reaching statistical significance.

CONCLUSIONS

Allogeneic pediatric HSCT patients had higher overall risk of hemorrhagic or thrombotic complications compared to autologous recipients in this study. HSCT for myeloid malignancies was a risk factor for higher complications.

Low paediatric thrombin generation is caused by an attenuation of prothrombin conversion

Thrombin generation (TG) is decreased in children. TG is determined by two underlying processes: the conversion of prothrombin to thrombin and the inactivation of thrombin. Therefore, lower TG capacity in children can either be caused by a reduction of prothrombin conversion, an increase of thrombin inactivation, or both. In 36 children and 8 adults, TG and the factors that determine thrombin inactivation (antithrombin, α2 Macroglobulin (α2M) and fibrinogen) were measured. Prothrombin conversion, thrombin inhibitor complex formation, and the overall thrombin decay capacity were determined. In silico modelling was performed to determine the contribution prothrombin conversion and thrombin inactivation to deviant paediatric TG. Both the amount of prothrombin converted and the maximal prothrombin conversion rate are significantly reduced in children as compared to adults. This is partly due to the prothrombin levels being lower and partly to a lower prothrombin conversion rate. The overall thrombin decay capacity is not significantly different in children, but α2Macroglobulin plays a more important role than it does in adults. In silico experiments demonstrate that reduced prothrombin conversion and to a lesser extent elevated α2M levels provide an explanation for low TG in children. Young age has a dual effect on prothrombin conversion. Lower plasma prothrombin levels result in decreased prothrombin conversion but the rate of prothrombin conversion is also decreased, i. e. the development of prothrombinase is lower than in adults.

[Neonatal arterial ischemic stroke: Which thrombotic biological risk factors to investigate and which practical consequences?]

All biological risk factors that have been previously identified to increase the risk of thrombosis in adults, have also been studied in neonates with arterial Ischemic Stroke (NAIS), but most studies were retrospective and included relatively low numbers of affected children. We therefore could not suggest recommendations with a strong level of evidence and only expert proposals potentially useful for clinical practice will be presented in this text. Despite these limitations, the extensive analysis of published data supported that factor V Leiden (FVL) and increased levels of Lp(a) could be significant risk factors for NAIS. Importantly, these 2 risk factors cannot be considered as having provoked NAIS, and moreover, they do not influence the prognosis and the immediate treatment. However, since the FVL may have an impact for the prescription of a thromboprophylaxis when the neonate will become adult, to look for its presence in affected patients may be justified. For clinical practice, the following propositions can be applied: 1. Routine testing for thrombophilia (AT, PC PS deficiency, FV Leiden or FII20210A) or for detecting other biological risk factors such as antiphospholipid antibodies, high FVIII, homocystein or Lp(a) levels, MTHFR thermolabile variant, should not be considered in neonates with NAIS. 2. Testing for FV Leiden can be performed in case of documented family history of venous thromboembolic disease. 3. Testing neonates for the presence of antiphospholipid antibodies (APA) is mandatory in case of clinical events suggesting antiphospholipid syndrome in the mother (vascular thrombosis, and/or pregnancy morbidity). 4. Routine testing for thrombophilia is not proposed in both parents in case of early death of the neonate, apart from APA in the mother.

Continuous Antithrombin III Administration in Pediatric Veno-Arterial Extracorporeal Membrane Oxygenation

The purpose of this retrospective case-control study is to determine the effect of continuous antithrombin III (ATIII) infusion on extracorporeal membrane oxygenation (ECMO) coagulation. All ECMO patients within the pediatric intensive care unit from January 2012 to July 2014 were included. Comparison was made between those who received continuous infusion ATIII through a standardized replacement protocol with historic controls receiving intermittent ATIII doses. Patients receiving the continuous infusion ATIII protocol spent more time in goal ACT range (71.9% vs 52.2%, p < 0.0001). Mean daily ATIII activity was also increased in study group (77.3% versus 68.6%, p = 0.04). No statistical differences in number of heparin dose changes per day (3 versus 3.22, p = 0.90) were present between the 2 groups. Only 28% of the historic controls receiving intermittent ATIII doses achieved normal ATIII activity as compared with 80% of study patients (p = 0.24). Maximum heparin dose was also lower in continuous infusion protocol group (p < 0.01). Compared with nonprotocolized intermittent dosing, the use of a continuous infusion ATIII protocol demonstrated increased time within goal ACT range at a lower heparin dose, no increase in hemostatic complications, and trends toward fewer heparin changes and lower blood product usage.

Osteonecrosis in children with acute lymphoblastic leukemia

The morbidity and toxicity associated with current intensive treatment protocols for acute lymphoblastic leukemia in childhood become even more important as the vast majority of children can be cured and become long-term survivors. Osteonecrosis is one of the most common therapy-related and debilitating side effects of anti-leukemic treatment and can adversely affect long-term quality of life. Incidence and risk factors vary substantially between study groups and therapeutic regimens. We therefore analyzed 22 clinical trials of childhood acute lymphoblastic leukemia in terms of osteonecrosis incidence and risk factors. Adolescent age is the most significant risk factor, with patients >10 years old at the highest risk. Uncritical modification or even significant reduction of glucocorticoid dosage cannot be recommended at this stage. A novel and innovative approach to reduce osteonecrosis-associated morbidity might be systematic early screening for osteonecrosis by serial magnetic resonance images. However, discriminating patients at risk of functional impairment and debilitating progressive joint disease from asymptomatic patients still remains challenging.

A survey of US and Canadian hospitals' paediatric massive transfusion protocol policies

BACKGROUND

Trauma is the leading cause of death in children >1 year of age, with haemorrhage as the most common cause of medically preventable deaths. While massive transfusion protocols (MTPs) have been investigated and used in adults to reduce death from haemorrhage, there are a paucity of published data on MTP practices and outcomes in children. This study aimed to survey current MTP policies and the frequency of activation at paediatric care centres.

STUDY DESIGN AND METHODS

We conducted a survey of MTPs at hospitals in the United States and Canada, including children's general hospitals, children's specialty hospitals and children's units in general hospitals. We collected information on how the MTP is activated, what therapeutics are given, frequency of its use, and how it is audited for compliance.

RESULTS

Forty-six survey responses were analysed. Physician discretion was the most common activation criteria (89%). A majority of sites (78%) targeted a 'high' (≥1 : 2) ratio of plasma to red blood cells (RBC). Fifteen percent of sites use antifibrinolytics in their MTPs. Eighty nine percent of sites have type-O RBC units and 48% of sites had thawed plasma units stored in an immediately available location.

CONCLUSION

There is a wide variation in MTPs among paediatric hospitals with regard to both activation criteria and products administered. This underscores the need for future prospective studies to determine the most effective resuscitation methods for paediatric populations to improve outcomes and therapeutic safety for massive bleeding.

Management of venous thrombosis in the pediatric patient

The incidence of venous thromboembolism in children has increased significantly over the past decade. The evaluation and management of the child with venous thromboembolism, while based on the adult experience, has its own particularities dictated by the differences in the hemostatic system of the newborn and child. The current review addresses the evaluation of pediatric patient with thrombosis as well as the established and emerging treatment interventions.

A retrospective analysis of outcomes of dalteparin use in pediatric patients: a single institution experience

BACKGROUND

Dalteparin is a commonly used low molecular weight heparin (LMWH) with extensive safety data in adults. With distinct advantages of once daily dosing and relative safety in renal impairment, it has been used off-label in pediatric practice; however, age-based dosing guidelines, safety and efficacy data in children are evolving.

OBJECTIVES

To report our institutional experience with the use of dalteparin in the treatment and prophylaxis of venous thromboembolism (VTE) in pediatric patients.

PATIENTS/METHODS

Retrospective chart review of all children (0-18years) that received dalteparin from December 1, 2000 through December 31, 2011. Doses per unit body weight per day (units/kg/day) were calculated for age-based group comparisons.

RESULTS

Of 166 patients identified, 116 (70%) received prophylactic doses while 50 (30%) received therapeutic doses of dalteparin. Infants (<1year) required significantly higher weight-based dosing to achieve therapeutic anti-Xa levels compared to children (1-10years) or adolescents (>10-18years) (mean dose units/kg/day; 396.6 versus 236.7 and 178.8 respectively, p<0.0001). Overall response rate, including complete and partial thrombus resolution, was 83%. Bleeding complications were minor and the rates were similar in therapeutic and prophylaxis patients. No significant differences in dosing or bleeding events were noted based on obesity or malignancy.

CONCLUSIONS

In our experience, dalteparin is effective for prophylaxis and therapy of VTE in pediatric patients. Dosing should be customized in an age-based manner with close monitoring of anti-Xa activity in order to achieve optimal levels, prevent bleeding complications, and to allow full benefit of prevention or therapy of thrombotic complications.