Interpretation of clotting tests in the neonate

Neonatal hemostasis and the use of thromboelastography/rotational thromboelastometry in the neonatal period

Developmental hemostasis refers to age-related alterations related to the progressive maturation of the hemostatic system. Although the conventional coagulation tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), are indeed helpful in coagulation workup, they do not accurately delineate the hemostasis in vivo. The viscoelastic tests, namely thromboelastography (TEG) and rotational thromboelastometry (ROTEM), seem to reflect hemostasis more accurately since they measure various clot parameters without excluding the cellular coagulation components. TEG and ROTEM have shown redaction in blood product administration when used in therapeutic algorithms in older children and adults, but their use in neonates is limited. This review summarizes the current literature regarding using these tests in the neonatal population. Several studies tried to resolve the lack of neonatal reference values of the TEG/ROTEM parameters by publishing neonatal reference ranges for various gestational age groups. Moreover, few studies concerning therapeutic hypothermia, neonates undergoing surgery, and critically ill neonates have shown some predictive value of these tests regarding bleeding events. Even though their results seem promising, larger studies of higher quality are needed to clarify any discrepancies and point out whether these tests have significant predictive value. In conclusion, viscoelastic tests need to be increasingly part of the NICUs' clinical routine and should be used along with conventional coagulation tests in transfusion therapy.

Contemporary tools for evaluation of hemostasis in neonates. Where are we and where are we headed?

The assessment of hemostatic disorders in neonates is crucial, but remains challenging for clinicians. Although the concept of developmental hemostasis is widely accepted among hemostasis specialists globally, it is probably under-recognized by clinicians and laboratory practitioners. In parallel with age-dependent hemostatic status maturation, comprehension of the differences between normal values is crucial for the accurate diagnosis of potential hemorrhagic and thrombotic disorders of the vulnerable neonatal population. This review outlines the basics of developmental hemostasis and the features of the available coagulation testing methods, with a focus on novel tools for evaluating the neonatal hemostatic profile. Common errors, issues, and pitfalls during the assessment of neonatal hemostasis are discussed, along with their impact on patient management. Current knowledge gaps and research areas are addressed. Further studying to improve our understanding of developmental hemostasis and its reflection on everyday clinical practice is warranted.

Coagulation parameters in very preterm infants

The aim of this study was to define normal percentile values of coagulation parameters in preterm infants below 32 weeks of gestational age. This retrospective cohort study was conducted at Istanbul Medical Faculty. Preterm infants who were born prior to 32 weeks of gestation, between 2011 and 2021 were included and evaluated for coagulation parameters. Blood samples obtained through umbilical catheters prior to administration of heparinized flushes/fluids, vitamin K or fresh frozen plasma (FFP). Infants with a major bleeding disorder, intrapartum asphyxia or a history of familial bleeding disorders were excluded. Infants were grouped according to their gestational ages and birth weights: less than 24, 25-26, 27-28, 29-30, 31-32 weeks and <500, 500-749, 750-999, 1000-1249, 1250-1499, more than 1500 g. Third to 97th percentile values of both prothrombin time (PT) and activated partial thromboplastin time (aPTT) were defined. A total of 420 preterm infants were included. The median value and range of gestational age and birth weight of the infants were 29 (22.3-32.9) weeks and 1150 (395-2790) g, respectively. PT values were similar between subgroups according to gestational age but longer in infants with a birth weight less than 1000 g. aPTT values in infants born less than 24 weeks of gestation were found significantly longer. As maturation of the coagulation system increases by gestational age, very preterm infants (<32 gestational week (GW)) are under increased risk of bleeding. Determination of normal percentile distribution of coagulation parameters for preterm infants will shed light on the interpretation of coagulation parameters of these infants and minimize unnecessary FFP administrations.

Fresh frozen plasma and cryoprecipitate: Can we safely reduce their use in the NICU?

OBJECTIVE

To study patterns of use of Fresh Frozen Plasma (FFP) and Cryoprecipitate (CRYO) in a level 4 NICU and assess what proportions were not supported by literature.

STUDY DESIGN

single centered retrospective observational. Charts of neonates admitted between 1/1/2010 to 12/31/2017 to CT Children's level 4 NICU were reviewed. Transfusions were assigned as "supported" or "non-supported" based on available evidence. Groups were compared using T-tests and chi-squared analyses.

RESULTS

of 4110 total admissions, 197 (4.8%) received a total of 461 transfusions (374 FFP, 87 CRYO). Only 59% of FFP and 60% CRYO were supported by literature. Within the "non-supported" group the largest category was neonates transfused prophylactically.

CONCLUSION

A large proportion of transfusions administered to neonates was not evidence-based, suggesting there are opportunities for improvement in use of these products.

Prevalence of hematologic complications on extracorporeal membranous oxygenation in critically ill pediatric patients: A systematic review and meta-analysis

OBJECTIVES

Despite advances in Extracorporeal Membranous Oxygenation (ECMO) equipment, hematologic complications remain significant in critically ill children. The aim of this study is to summarize prevalence of hematologic complications for children and neonates.

METHODS

MEDLINE, PubMed and Scopus databases were searched focusing on the period from January 01, 2017 to October 01, 2022. The population included critically ill children and neonates with hematologic complications. The review included all aspects of related complications including hemorrhage, thrombosis, and hemolysis. We performed random effects meta-analyses. The primary outcome measure was overall hematologic complications. Secondary outcomes are changes in the prevalence of hemorrhagic complications. Risk of bias of included studies was assessed using the Joanna Briggs Institute checklist.

RESULTS

The systematic search identified 37 studies totaling 10,659 critically ill pediatric patients receiving ECMO. The pooled prevalence of hemorrhagic complications, thrombotic complications and hemolysis among pediatric patients requiring ECMO was 43.7 % (95 % CI: 28.6 % to 58.9 %, P < 0.001), 27.6 % (95 % CI: 20.4 % to 34.8 %, P < 0.001), 34.3 % (95 % CI: 22.9 % to 45.7 %, P < 0.001). The prevalence of hemorrhagic complications was represented in descending order: surgical site (21.6 %, 95 % CI: 10.3 % to 32.9 %); cannulation site (20.6 %, 95 % CI: 11.8 % to 29.3 %); intracranial (12.2 %, 95 % CI: 9.5 % to 15.0 %); pulmonary (7.7 %, 95 % CI: 5.9 % to 9.6 %); gastrointestinal (6.0 %, 3.7 % to 8.4 %). For the assessment of thrombotic complications, thrombosis in cannulation site had a higher prevalence (28.5 %, 95 % CI: 22.1 % to 34.9 %), followed by DIC (13.5 %, 95 % CI: 8.7 % to 18.3 %) and intracranial thrombosis (4.5 %, 95 % CI: 1.4 % to 7.6 %). Predictors of increased prevalence of hemorrhagic complications included age (P = 0.017) and VV-ECMO support mode (P = 0.029).

CONCLUSIONS

Among critically ill pediatric patients, there was a series of hematologic complications can occur during ECMO support. Physicians should pay special attention to the management and establish appropriate treatment programs to reduce the occurrence of hematologic complications.

Reference Intervals for Coagulation Parameters in Developmental Hemostasis from Infancy to Adolescence

Background: The objective of this study was to establish the age and sex-dependent reference intervals for coagulation assays evaluated in healthy children, ranging from 0 days to 16 years old. Methods: PT, aPTT, Fibrinogen (functional), Antithrombin activity, Protein C anticoagulant activity, Protein S free antigen, Thrombin time, D-Dimer, Von Willebrand Factor antigen, Lupus anticoagulant (screening), extrinsic and intrinsic pathway factors, and activated Protein C resistance were evaluated using STA-R Max². Results: A total of 1280 subjects (671 males and 609 females) were divided into five groups, according to their age: 0–15 days (n = 280, 174 M and 106 F), 15–30 days (n = 208, 101 M and 107 F), 1–6 months (n = 369, 178 M and 191 F), 6–12 months (n = 214, 110 M and 104 F), and 1–16 years (n = 209, 108 M and 101 F). The 95% reference intervals and the 90% CI were established using the Harrell–Davis bootstrap method and the bootstrap percentile method, respectively. Conclusions: The present study supports the concept that adult and pediatric subjects should be evaluated using different reference intervals, at least for some coagulation tests, to avoid misdiagnosis, which can potentially lead to serious consequences for patients and their families, and ultimately the healthcare system.

Use of Fresh-frozen Plasma in Newborn Infants

Nearly 10% of premature and critically ill infants receive fresh-frozen plasma (FFP) transfusions to reduce their high risk of bleeding. The authors have only limited data to identify relevant clinical predictors of bleeding and to evaluate the efficacy of FFP administration. There is still no consensus on the optimal use of FFP in infants who have abnormal coagulation parameters but are not having active bleeding. The aims of this review are to present current evidence derived from clinical studies focused on the use of FFP in neonatology and then use these data to propose best practice recommendations for the safety of neonates receiving FFP.

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.

Neonatal Sepsis and Hemostasis

Neonatal sepsis is considered critical for a significant increase in neonatal morbidity and mortality among hospitalized neonates. Neonatal sepsis, in most cases, coexists with coagulopathy, which can prove to be life-threatening. Complex molecular and cellular systems are involved in the cross-talk between inflammation and hemostasis during sepsis. Disturbances in the regulating systems of the vascular endothelium, and platelet–endothelial and platelet–neutrophil interactions play a pivotal role in both inflammation and coagulation. This complex process is poorly understood in neonates. In addition to the developmental maturation of hemostasis and the immune response in neonatal sepsis, a cellular model of hemostasis during sepsis should be taken into account. This review focused on the molecular and cellular mechanisms underlying inflammation and hemostasis during neonatal sepsis, taking the developmental immune response and developmental hemostasis into account in order to provide future diagnostic approaches to be applied in everyday clinical settings. Regarding the diagnostic modalities, we briefly provide the limitations of the currently used conventional coagulation assays, focusing on viscoelastic tests and platelet flow cytometry.

Plasma and Platelet Transfusion Strategies in Critically Ill Children With Malignancy, Acute Liver Failure and/or Liver Transplantation, or Sepsis: From the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding

OBJECTIVES

To present the consensus statements with supporting literature for plasma and platelet transfusions in critically ill neonates and children with malignancy, acute liver disease and/or following liver transplantation, and sepsis and/or disseminated intravascular coagulation from the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding.

DESIGN

Systematic review and consensus conference of international, multidisciplinary experts in platelet and plasma transfusion management of critically ill children.

SETTING

Not applicable.

PATIENTS

Critically ill neonates and children with malignancy, acute liver disease and/or following liver transplantation, and sepsis and/or disseminated intravascular coagulation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A panel of 13 experts developed evidence-based and, when evidence was insufficient, expert-based statements for plasma and platelet transfusions in critically ill neonates and children with malignancy, acute liver disease and/or following liver transplantation, and sepsis and/or disseminated intravascular coagulation. These statements were reviewed and ratified by the 29 Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding experts. A systematic review was conducted using MEDLINE, EMBASE, and Cochrane Library databases, from inception to December 2020. Consensus was obtained using the Research and Development/University of California, Los Angeles Appropriateness Method. Results were summarized using the Grading of Recommendations Assessment, Development, and Evaluation method. We developed 12 expert consensus statements.

CONCLUSIONS

In the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding program, the current absence of evidence for use of plasma and/or platelet transfusion in critically ill children with malignancy, acute liver disease and/or following liver transplantation, and sepsis means that only expert consensus statements are possible for these areas of practice.

The role of the calibrated automated thrombogram in neonates: describing mechanisms of neonatal haemostasis and evaluating haemostatic drugs

Premature infants are at high risk of haemorrhage and thrombosis. Our understanding of the differences between the neonatal and adult haemostatic system is evolving. There are several limitations to the standard coagulation tests used in clinical practice, and there is currently a lack of evidence to support many of the transfusion practices in neonatal medicine. The evaluation of haemostasis is particularly challenging in neonates due to their limited blood volume. The calibrated automated thrombogram (CAT) is a global coagulation assay, first described in 2002, which evaluates both pro- and anti-coagulant pathways in platelet-rich or platelet-poor plasma. In this review, the current applications and limitations of CAT in the neonatal population are discussed.Conclusion: CAT has successfully elucidated several differences between haemostatic mechanisms in premature and term neonates compared with adults. Moreover, it has been used to evaluate the effect of a number of haemostatic drugs in a pre-clinical model. However, the lack of evidence of CAT as an accurate predictor of neonatal bleeding, blood volume required and the absence of an evidence-based treatment algorithm for abnormal CAT results limit its current application as a bedside clinical tool for the evaluation of sick neonates. What is Known: • The Calibrated automated thrombogram (CAT) is a global coagulation assay which evaluates pro- and anti-coagulant pathways. • CAT provides greater information than standard clotting tests and has been used in adults to evaluate bleeding risk. What is New: • This review summarises the physiological differences in haemostasis between neonates and adults described using CAT. • The haemostatic effect of several drugs has been evaluated in neonatal plasma using CAT.

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.

Haematological parameters and coagulation in umbilical cord blood following COVID-19 infection in pregnancy

Objective

The aim of this study was to evaluate infants, born to women with SARS-CoV-2 detected during pregnancy, for evidence of haematological abnormalities or hypercoagulability in umbilical cord blood.

Study design

This was a prospective observational case-control study of infants born to women who had SARS-CoV-2 RNA detected by PCR at any time during their pregnancy (n = 15). The study was carried out in a Tertiary University Maternity Hospital (8,500 deliveries/year) in Ireland. This study was approved by the Hospital Research Ethics Committee and written consent was obtained. Umbilical cord blood samples were collected at delivery, full blood count and Calibrated Automated Thrombography were performed. Demographics and clinical outcomes were recorded. Healthy term infants, previously recruited as controls to a larger study prior to the outbreak of COVID-19, were the historical control population (n = 10).

Results

Infants born to women with SARS-CoV-2 had similar growth parameters (birth weight 3600 g v 3680 g, p = 0.83) and clinical outcomes to healthy controls, such as need for resuscitation at birth (2 (13.3%) v 1 (10%), p = 1.0) and NICU admission (1 (6.7%) v 2 (20%), p = 0.54). Haematological parameters (Haemoglobin, platelet, white cell and lymphocyte counts) in the COVID-19 group were all within normal neonatal reference ranges. Calibrated Automated Thrombography revealed no differences in any thrombin generation parameters (lag time (p = 0.92), endogenous thrombin potential (p = 0.24), peak thrombin (p = 0.44), time to peak thrombin (p = 0.94)) between the two groups.

Conclusion

In this prospective study including eligible cases in a very large population of approximately 1500 women, there was no evidence of derangement of the haematological parameters or hypercoagulability in umbilical cord blood due to COVID-19. Further research is required to investigate the pathological placental changes, particularly COVID-19 placentitis and the impact of different strains of SARS-CoV-2 (particularly the B.1.1.7 and the emerging Delta variant) and the severity and timing of infection on the developing fetus.

Diagnostic Scores and Treatment Options for Acute Disseminated Intravascular Coagulation in Children

Disseminated intravascular coagulation (DIC) is a thrombo-hemorrhagic condition that commonly accompanies life-threatening illnesses in children and is associated with significant morbidity and mortality. Treatment of underlying conditions, hemodynamic support, and replacement therapy with blood components is the mainstay of DIC management. Limited research studies have supported the use of antithrombin (AT), recombinant thrombomodulin (rTM), and protein C concentrates (PrCC). Although there have been several studies and advancements in the DIC treatment in adults, data in pediatric patients are limited, and the consensus is lacking. Evidence validating the use of diagnostic scoring systems in the pediatric population is also limited. Since the hemostatic system differs significantly in children, especially in neonates, management of DIC is also different in children from that of adults, and there is a dire need for good quality research studies in this aspect.

We reviewed more than 100 articles in PubMed, Cochrane database, and Google Scholar. This traditional review article discusses different scoring systems for diagnosing DIC in pediatric patients, and different pharmacological treatment options for acute DIC in this population. This study mainly focuses on papers published from 1990 to 2021 and includes papers in all languages involving humans only.

Impact of blood sampling technique on reproducibility of viscoelastic coagulation monitor (VCM™) system test results in the neonate

Purpose: To evaluate the reproducibility of the results of the viscoelastic coagulation test (VCT) performed with a new viscoelastic coagulation monitor (VCM™ - Entegrion) on native blood obtained by heel prick blood sampling with two different techniques compared to the standard blood collection in the newborn.Methods: Three blood samples were tested with the VCM analyzer in each of the 67 study subjects admitted to our level 3 neonatal intensive care unit. Standard blood collection (S) was performed by direct puncture of a peripheral vessel or by drawing of blood in a syringe connected to an arterial or venous catheter. Then, two more blood samples were drawn through a single heel prick. The first heel prick blood sample (HP1) was collected in the sample well through the attached metal capillary while the second (HP2) was poured directly into the sample well. Blood samples were automatically drawn into their pre-warmed cartridges and inserted into the VCM analyzers set up for analyses, which ran for one hour. VCT blood variables included clotting time (CT), clot formation time (CFT), angle alpha (α), amplitude at 10 and 20 min (A10 and A20), maximum clot firmness (MCF), and lysis indexes at 30 and 45 min (LY30 - LY45). Agreement was quantified by calculating the mean difference and SD between measurements of VCT blood variables from S, HP1 and HP2 blood samples. The 95% limits of agreement were calculated by the Bland & Altman method, using the upper or lower limit of agreement to interpret the variability of the measurements. The Kendall's τ correlation coefficient evaluated the interdependence between SD and intra-measurement mean.Results: S blood samples were easily obtained in all the study subjects, while mild difficulties were recorded in 3/67 infants (4.5%) with the HP1 blood sampling and in 5/67 infants (7%) with the HP2 blood sampling. Pairwise comparison of test results performed on blood samples drawn with HP1 and HP2 techniques showed moderate agreement for CT and α-angle, strong agreement for CFT, LY30 and LY45 and almost perfect agreement for A10, A20 and MCF. In pairwise comparison of VCM analyses performed on blood samples drawn with S technique vs HP1 and HP2 techniques, Kendall's τ correlation coefficient was significant for CT (S vs HP1 and HP1 vs HP2), CFT (S vs HP1 and S vs HP2), α-angle (S vs HP1) and MCF (S vs HP1). This suggests that the measurement error depends on the extent of the measurement. The overall ICC for blood sampling techniques ranged from 0.289 to 0.879 with best agreement observed for CFT (strong) and for A10, A20 and MCF (almost perfect). The LY30 index was the least repeatable measurement (poor agreement). The VCM analysis performed on the blood sample drawn with the HP1 technique showed the best repeatability compared with that performed with the S blood-sampling technique.Conclusion. VCT test results performed with the VCM analyzer on native blood drawn by heel prick in neonates are comparable to those obtained from standard blood samples. This could allow for a widespread, real-time assessment of the overall bedside haemostasis of these small patients.

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.

Closing the evidence to practice gap in neonatal transfusion medicine

Significant resources are directed towards world-class research projects, but the findings are not necessarily translated into better healthcare outcomes, either at all or in a sustained way. There is a clear need to dedicate further resources to understanding how to promote the uptake of evidence and effectively change neonatal transfusion practice to improve outcomes. Approaching blood transfusion behaviour change more systematically, and working across disciplines and involving families, holds the potential to increase the rate of uptake of emerging evidence in clinical practice. This approach holds the potential to save costs, conserve resources, and improve clinical outcomes. Our paper focuses on the use of quality improvement to bridge the gap between evidence-based knowledge and transfusion practice in neonatal units around the world.

Hemostatic Challenges in Neonates

The neonatal hemostatic system is strikingly different from that of adults. Among other differences, neonates exhibit hyporeactive platelets and decreased levels of coagulation factors, the latter translating into prolonged clotting times (PT and PTT). Since pre-term neonates have a high incidence of bleeding, particularly intraventricular hemorrhages, neonatologists frequently administer blood products (i.e., platelets and FFP) to non-bleeding neonates with low platelet counts or prolonged clotting times in an attempt to overcome these "deficiencies" and reduce bleeding risk. However, it has become increasingly clear that both the platelet hyporeactivity as well as the decreased coagulation factor levels are effectively counteracted by other factors in neonatal blood that promote hemostasis (i.e., high levels of vWF, high hematocrit and MCV, reduced levels of natural anticoagulants), resulting in a well-balanced neonatal hemostatic system, perhaps slightly tilted toward a prothrombotic phenotype. While life-saving in the presence of active major bleeding, the administration of platelets and/or FFP to non-bleeding neonates based on laboratory tests has not only failed to decrease bleeding, but has been associated with increased neonatal morbidity and mortality in the case of platelets. In this review, we will present a clinical overview of bleeding in neonates (incidence, sites, risk factors), followed by a description of the key developmental differences between neonates and adults in primary and secondary hemostasis. Next, we will review the clinical tests available for the evaluation of bleeding neonates and their limitations in the context of the developmentally unique neonatal hemostatic system, and will discuss current and emerging approaches to more accurately predict, evaluate and treat bleeding in neonates.

Hemostatic Testing in Critically Ill Infants and Children

Children with critical illness frequently manifest imbalances in hemostasis with risk of consequent bleeding or pathologic thrombosis. Traditionally, plasma-based tests measuring clot formation by time to fibrin clot generation have been the "gold standard" in hemostasis testing. However, these tests are not sensitive to abnormalities in fibrinolysis or in conditions of enhanced clot formation that may lead to thrombosis. Additionally, they do not measure the critical roles played by platelets and endothelial cells. An added factor in the evaluation of these plasma-based tests is that in infants and young children plasma levels of many procoagulant and anticoagulant proteins are lower than in older children and adults resulting in prolonged clot generation times in spite of maintaining a normal hemostatic "balance." Consequently, newer assays directly measuring thrombin generation in plasma and others assessing the stages hemostasis including clot initiation, propagation, and fibrinolysis in whole blood by viscoelastic methods are now available and may allow for a global measurement of the hemostatic system. In this manuscript, we will review the processes by which clots are formed and by which hemostasis is regulated, and the rationale and limitations for the more commonly utilized tests. We will also discuss selected newer tests available for the assessment of hemostasis, their "pros" and "cons," and how they compare to the traditional tests of coagulation in the assessment and management of critically ill children.

Elevated International Normalized Ratio (INR) is Associated With an Increased Risk of Intraventricular Hemorrhage in Extremely Preterm Infants

INTRODUCTION

The international normalized ratio (INR), a standardized method of reporting the prothrombin time, can be a surrogate marker of the vitamin K-dependent coagulation pathways.

OBJECTIVE

To evaluate the relationship between INR measurements in the first 48 hours of life and subsequent development of intraventricular hemorrhage (IVH) in extremely preterm infants.

MATERIALS AND METHODS

A single-center retrospective, observational cohort study of infants born at <28 weeks gestation. The main outcome measure was defined as the degree of IVH seen on cranial ultrasound examinations at day 7 postnatal age.

RESULTS

Of 200 infants, 109 (mean gestational age, 25.2 wk [SD, 1.27]) had coagulation results available. Of 109, 26 developed IVH. Elevated INR was associated with increased risk of a severe IVH (odds ratio [OR] 6.50; 95% confidence interval [CI], 1.65-25.62; P=0.008) adjusted for gestation, birth weight, and sex. INR was significantly associated with severe IVH in infants who did not receive blood products (OR, 64.60; 95% CI, 1.35-3081.25; P=0.035), but not in those who did (OR, 2.93; 95% CI, 0.67-12.71; P=0.151) (Pinteraction=0.086).

CONCLUSION

An elevated INR in the first 48 hours of life may be useful to identify preterm infants at risk of severe IVH and may guide strategies to prevent the development, or limit the extension, of IVH.

Disseminated Intravascular Coagulation in the Neonate

Disseminated intravascular coagulation (DIC) is a serious secondary disease that alters the events in the clotting cascade. DIC leads to microclots in the peripheral vasculature. The uncontrolled formation of these clots consumes the body's clotting factors, which precipitates bleeding. Neonates, defined as newborns zero to one month old, are born with slightly altered hemostasis, also known as developmental coagulopathy. This coagulopathy puts neonates at a greater risk of developing DIC, specifically when additional body systems have been compromised by a primary disease. Because of the serious nature of this disease and its precipitating factors, advanced practitioners should study the nuances of DIC to provide accurate diagnosis and proper treatment. The aim of this article is to discuss the pathophysiology behind DIC along with etiologies, diagnosis, treatment, and prognosis in neonates, along with gaps in current research.

Neonatal haemostasis

The maturation and postnatal development of the human coagulation system results in significant and important differences in the coagulation and fibrinolysis of neonates and young children compared to older children and adults. Importantly, these differences, which mostly reflect the immaturity of the neonatal haemostasis system, are functionally balanced. Healthy neonates show no signs of easy bruising or other bleeding diathesis and no increased tendency to thrombosis for any given stimulus compared to adults.

Systemic diseases may affect haemostasis, thus predisposing ill neonates to increased risk for haemorrhagic or thrombotic complications. In hospitalized children, neonates have increased risk of developing thrombosis compared to infants and children, mostly associated with the presence of central venous catheter. For diagnosis of haemostasis disorders, diagnostic laboratories processing pediatric samples should use age, analyzer and reagent appropriate reference ranges. Age specific guidelines should be followed for the management of neonates with hemostatic disorders.

Fresh frozen plasma transfusion - a risk factor for pulmonary hemorrhage in extremely low birth weight infants?

AIM

To evaluate risk factors for pulmonary hemorrhage (PH) in extremely low birth weight infants (ELBW) taking into consideration coagulation screens, platelet counts, transfusion of fresh frozen plasma (FFP), and platelet concentrates prior to PH.

PATIENTS AND METHODS

A retrospective case-control study consisting of 20 ELBW infants with PH and 40 matched controls. Coagulation screens, platelet counts at birth and at onset of PH, and transfusion frequencies prior to PH were compared to case-controls at birth and 24-96 h after birth.

RESULTS

While the initial platelet counts, fibrinogen concentrations, and international normalized ratios were similar in PH infants and controls, the activated partial prothrombin time was prolonged (P=0.05). Compared to 28% of case controls (P<0.05), 55% of infants with later PH received FFP prior to PH. Platelet counts were significantly lower at onset of PH (median 81/nL; range: 37-236/nL) compared to controls (166/nL; 27-460/nL; P<0.005). Multivariate analysis indicated a lack of antenatal steroids, supplemental oxygen, and transfusion of FFP as independent risk factors for PH.

CONCLUSION

Prolonged activated partial thromboplastin time (aPTT) might be associated with PH. PH does not primarily depend upon severe thrombocytopenia. A developmental mismatch in hemostasis by transfusion of adult donor plasma should be considered a risk factor for PH.

Neonatal Plasma Transfusion: An Evidence-Based Review

Several clinical scenarios for plasma transfusion are repeatedly identified in audits, including treatment of bleeding in association with laboratory evidence of coagulopathy, correction of disseminated intravascular coagulation, prevention of intraventricular hemorrhage, management of critically ill neonates (eg, during sepsis or as a volume expander), or correction of markers of prolonged coagulation in the absence of bleeding. The findings of at least one national audit of transfusion practice indicated that almost half of plasma transfusions are given to neonates with abnormal coagulation values with no evidence of active bleeding, despite the limited evidence base to support the effectiveness of this practice. Plasma transfusions to neonates should be considered in the clinical context of bleeding (eg, vitamin K dependent), disseminated intravascular coagulation, and very rare inherited deficiencies of coagulation factors. There seems to be no role for prophylactic plasma to prevent intraventricular hemorrhage or for use as a volume expander.

Coagulation indices in very preterm infants from cord blood and postnatal samples

BACKGROUND

Very premature infants are at high risk of bleeding complications; however, few data exist on ranges for standard coagulation tests.

OBJECTIVES

The primary objective of this study was to measure standard plasma coagulation tests and thrombin generation in very premature infants compared with term infants. The secondary objective was to evaluate whether an association existed between coagulation indices and intraventricular hemorrhage (IVH).

PATIENTS/METHODS

Cord and peripheral blood of neonates < 30 weeks gestational age (GA) was drawn at birth, on days 1 and 3 and fortnightly until 30 weeks corrected gestational age. Prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen and coagulation factor levels were measured and tissue factor-stimulated thrombin generation was characterized. Control plasma was obtained from cord blood of term neonates.

RESULTS

One hundred and sixteen infants were recruited. Median (range) GA was 27.7 (23.7-29.9) weeks and mean (SD) birth weight was 1020 (255) g. Median (5th-95th percentile) day 1 PT, APTT and fibrinogen were 17.5 (12.7-26.6) s, 78.7 (48.7-134.3) s and 1.4 (0.72-3.8) g L(-1) , respectively. No difference in endogenous thrombin potential between preterm and term plasma was observed, where samples were available. Levels of coagulation factors II, VII, IX and X, protein C, protein S and antithrombin were reduced in preterm compared with term plasma. Day 1 APTT and PT were not associated with IVH.

CONCLUSION

In the largest cross-sectional study to date of very preterm infants, typical ranges for standard coagulation tests were determined. Despite long clotting times, thrombin generation was observed to be similar in very preterm and term infants.

Fresh Frozen Plasma Use in a Neonatal Unit in South Africa

BACKGROUND

Despite limited evidence, fresh frozen plasma (FFP) transfusions are a relatively common neonatal procedure.

OBJECTIVES

Quantify FFP usage in our unit; determine indications for transfusions and compliance with published guidelines.

METHODS

Data were retrospectively collected on infants who received FFP from January 2009 to December 2013.

RESULTS

Admissions totalled 10 912 infants during the study period. In total, 113 case notes were reviewed and 142 FFP transfusions were administered. Infants receiving FFP had a high mortality rate (54.87%) and an increased odds ratio for mortality 17.9 (95% confidence interval 12.0-26.6). In total, 75% FFP transfusions were compliant with guidelines. The difference between pre- and post-transfusion coagulation profile in 36.3% of infants was not statistically significant.

CONCLUSIONS

FFP was often used in accordance with published guidelines in our neonatal unit. However, the appropriate use and effectiveness of FFP in improving neonatal outcomes undermines the rationale for FFP usage in current guidelines.