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

Expanding beyond trauma: Characterizing low titer group O whole blood (LTOWB) use in children requiring massive transfusion protocol activation

INTRODUCTION

Data regarding low titer group O whole blood (LTOWB) use for hemostatic resuscitation is largely derived from trauma cohorts; studies regarding its use in uninjured pediatric patients are lacking.

METHODS

The blood bank database from a single academic pediatric hospital with a massive transfusion protocol (MTP) allowing the use of LTOWB for any severe bleeding etiology was queried between 2016 and 2023. Pediatric (age <18 years) recipients of LTOWB were included; injured children were excluded. Data recorded included demographics, bleeding etiology, blood volumes, mortality (24-h and in-hospital), organ dysfunction, and, when available, posttransfusion biochemical markers of hemolysis.

RESULTS

Of 112 recipients of LTOWB, 16 met inclusion criteria. Median (IQR) age was 13 years (8-16) and 8/16 (50%) were male. MTP was most often activated on the day of admission (median (IQR) = day 0 (0-1)), and the bleeding etiology was variable, including perioperative (8/16; 50%), gastrointestinal bleed (5/16; 31%), and extracorporeal membrane oxygenation (ECMO) cannulation (3/16; 19%). The median (IQR) weight-adjusted volume of LTOWB transfused was 19 (10-26) mL/kg, and most children (13/16; 81%) received component blood products in addition to LTOWB. The 24-h mortality rate was 25% (4/16) and in-hospital mortality was 44% (7/16). The most common complication was AKI (10/16; 63%). There were no significant differences in biochemical hemolysis markers between group O (n = 7) and non-group O (n = 9) LTOWB recipients at any time point (p = .07-.99).

CONCLUSIONS

LTOWB use was feasible in the resuscitation of children with various bleeding etiologies requiring massive transfusion. Larger prospective investigations are needed to inform guidelines for optimal use in this cohort.

LEVEL OF EVIDENCE

Retrospective Observational Study.

Updates in perioperative hemostasis in the pediatric surgical patient

PURPOSE OF REVIEW

Maintaining hemostasis in pediatric patients undergoing major surgery presents unique challenges for the anesthesiologist. This review presents the most recent updates on pediatric perioperative bleeding and hemostasis management.

RECENT FINDINGS

Patient blood management (PBM) programs remain scarcely implemented, but recent evidence for restrictive transfusion thresholds and reduction in allogeneic blood products in the pediatric population is growing. Notable updates include support for pediatric PBM programs, restrictive transfusion thresholds, increased use of viscoelastic testing, safety and efficacy of whole blood, and management of coagulopathy in trauma.

SUMMARY

PBM programs and their key components have gained traction in the pediatric population in recent years: treating preoperative anemia, optimizing coagulation, and tolerating physiologic anemia through restrictive transfusion thresholds. Further evidence in the pediatric population is needed to guide the anesthesiologist.

Forty-eight-hour cold-stored whole blood in paediatric cardiac surgery: Implications for haemostasis and blood donor exposures

BACKGROUND AND OBJECTIVES

Cold-stored whole blood (CS-WB) in paediatric cardiac surgery is making a resurgence, given its identified benefits compared to conventional blood component therapy (CT).

STUDY DESIGN AND METHODS

A single-centre retrospective study was conducted from January 2018 to October 2018 by including children <18 years of age undergoing cardiac surgery requiring cardiopulmonary bypass. ABO-compatible CS-WB from non-directed random donors was leukoreduced with platelet-sparing filters and compared with CT.

RESULTS

Fifty-seven patients (30, 53% CS-WB; 27, 47% CT) were studied. Patient demographics were similar, although CT patients were cooled to a lower intra-operative temperature. Blood product requirements 24 h post operation were less in the CS-WB group (11.1 vs. 26.7 mL/kg, p = 0.048). Twelve (40%) patients in the CS-WB cohort had more than one donor exposure versus 25 (93%) in the CT group (p < 0.001). CT patients compared to CS-WB patients had a greater decrease in pre-operative versus 48-h post-operative haemoglobin, platelets and prothrombin time. Patients who received CT compared to CS-WB had a trend towards higher median (interquartile range [IQR]) chest-tube output (mL/kg/h) in the first 4 h post cardiac intensive care unit (ICU) admission (2.1 [0.8, 3] vs. 1.6 [0.8, 2.2], p = 0.197). There was no difference in antifibrinolytic use, length of stay, sepsis, acute kidney injury or wound infection. Survival to discharge was similar.

CONCLUSION

CS-WB in paediatric cardiac surgery may reduce donor exposure and improve haemostatic balance. Future multi-centre prospective studies are needed to validate these findings and identify patients who would benefit from CS-WB in paediatric cardiac surgery.

The value of thromboelastography to neonatology

Hemostatic derangements are common in critically ill and premature neonates. Nevertheless, hemostasis assessment in neonates is still challenging. The hemostatic system undergoes age-related physiological changes during its maturation and exhibits quantitative and qualitative differences between infants and adults. Conventional coagulation tests are mainly responsive to procoagulant factors, regardless of the contribution of cellular elements, anticoagulants and fibrinolytic contributors and, therefore, their role in predicting bleeding in neonatal acquired coagulopathy is somewhat limited. Viscoelastic coagulation tests offer a promising alternative, enabling a bedside and real-time assessment of the entire hemostatic process in short turn-around times with a limited amount of blood. These tests allow a targeted hemostatic monitoring and a tailored management of blood products and anticoagulation. The routine use of VCTs in the NICU remains limited, especially for premature infants, due to the lack of established normative ranges. In this review we will provide an overview of the main evidence related to the clinical application of viscoelastic monitoring in the neonatal setting.

Hemostatic derangements associated with cardiopulmonary bypass predict outcomes in pediatric patients undergoing corrective heart surgery

BACKGROUND

Understanding of the hemostatic and complement alterations associated with cardiopulmonary bypass (CPB) in pediatric patients and the impact of these alterations on outcome is limited.

OBJECTIVES

The present study prospectively characterized these alterations and their association with postoperative outcomes in pediatric CPB.

METHODS

All patients aged <21 years undergoing CPB at the authors' institution between 2020 and 2021 who weighed >3 kg, were >36 weeks gestational age, and had no known prothrombotic or hemorrhagic disorders were eligible. Blood samples were analyzed for multiple hemostatic and complement biomarkers pre-, intra-, and 24 hours post-CPB. Biomarker levels were compared to clinical outcomes, including chest tube output (CTO).

RESULTS

Fifty consecutive patients were enrolled. CPB resulted in multiple significant alterations in hemostatic and complement components. Lower platelet counts (<80 × 109 platelets/L) at CPB termination were associated with increased postoperative CTO (P = .003). Lower factor (F)VIII levels (<60 IU/dL) at the end of CPB were associated with a longer hospital stay (P < .001) and increased postoperative CTO (P < .001). Patients undergoing staged single ventricle reconstruction were more likely to have lower platelet counts at CPB termination (P = .009) and higher CTO postoperatively (P = .001) than patients undergoing other types of surgical repair. These differences were not due to different preoperative platelet counts, increased incidences of circulatory arrest, or longer CPB times.

CONCLUSION

These data suggest that intraoperative alterations in hemostatic system components may predict postoperative outcomes in pediatric CPB. Further study is needed to determine if interventions targeting platelets or FVIII could improve outcomes in pediatric CPB.

Trauma-induced coagulopathy across age pediatric groups: A retrospective cohort study evaluating testing and frequency

BACKGROUND

Trauma-induced coagulopathy (TIC) is associated with negative outcomes. Pediatric TIC has been described most often in older children. Children undergo normal developmental hemostasis, but it is unknown how this process impacts the risk of TIC across childhood.

AIMS

To understand variations in coagulation testing and TIC across pediatric age groups.

METHODS

We evaluated testing patterns of coagulation studies at presentation and over the first 72 h of hospitalization by pediatric age group at a large, Level I trauma center, 2015-2020. The frequency of TIC was determined using published, age-specific reference ranges and controlling for injury severity. We performed subgroup analyses of those with isolated severe traumatic brain injury (TBI) and those who presented directly from the scene of injury.

RESULTS

Data from 2409 pediatric patients were available; 333 patients had isolated severe TBI. Children <1 year were least likely to be tested for TIC at presentation and over the first 72 h, even among the most injured. Fibrinogen testing was uncommon, regardless of injury severity. TIC was common: 22% of patients had TIC at presentation and 35% by 72 h. Greater injury severity was associated with TIC. Children 1-4 and 5-9 years had a higher frequency of TIC at presentation and over 72 h compared to older children in the least injured cohort. We saw no difference in frequency of TIC between age groups in the subset with isolated severe TBI. Using age-specific criteria, patients most often met TIC criteria by INR/PT, followed by platelet count, and least commonly by aPTT. The presence of TIC was associated with in-hospital mortality (OR 4.10, 95% CI 2.06-8.17).

CONCLUSIONS

Significant sampling bias exists in clinical data collection among injured children and adolescents. Contrary to previous reports and using age-specific TIC criteria, younger children are not at lower risk of TIC than older children when controlling for injury severity.

HINODE study: haemophilia A in infancy and newborns - protocol for a prospective, multicentre, observational study evaluating the coagulation potential and safety of emicizumab prophylaxis

INTRODUCTION

Emicizumab prophylaxis is approved for people of all ages with haemophilia A (HA) including infants and children. Although previous studies have demonstrated the efficacy and tolerability of emicizumab in infants with HA, real-world data on emicizumab use in infants are limited. The Haemophilia A in Infancy and NewbOrns: multi-instituional prospective observational study to assess the efficacy anD safety of Emicizumab (HINODE) study aims to evaluate the coagulation potential and safety of emicizumab prophylaxis in infants with congenital HA from birth to <12 months of age.

METHODS AND ANALYSIS

This is a multicentre, observational study conducted in Japan in infants with congenital HA aged <12 months who are receiving or are scheduled to receive prophylactic emicizumab at an approved dosing regimen: 1.5 mg/kg weekly, 3 mg/kg every 2 weeks or 6 mg/kg every 4 weeks. The target inclusion is 50 infants. The primary endpoint is to evaluate the relationship between global coagulation test parameters (using clot waveform analysis and thrombin generation assay) and plasma emicizumab concentrations in infants aged from 6 to <12 months. Secondary endpoints include evaluating coagulation profiles in infants aged <6 months and changes between the age of <6 and 6 to <12 months. Additionally, coagulation parameters will be evaluated with the in vitro addition of anti-idiotype antibodies against emicizumab or the addition of a factor VIII product in infants aged from 6 to <12 months. The study will also evaluate adverse events and bleeds.

ETHICS AND DISSEMINATION

The study was approved by the MINS Clinical Trial Review Committee (no. 230214) and will be conducted in compliance with the Declaration of Helsinki, the Act on the Protection of Personal Information and the Guidance of Ethical Guidelines for Medical and Biological Research Involving Human Subjects. Written informed consent for participation in the study will be obtained from a legally acceptable representative. Results will be published in scientific/medical journals and presented at international congresses.

TRIAL REGISTRATION NUMBER

Japan Registry of Clinical Trials; jRCT1031230264.

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.

Estimation of gestational age-specific reference intervals for coagulation assays in a neonatal intensive care unit using real-world data

BACKGROUND

Interpretation of coagulation testing in neonates currently relies on reference intervals (RIs) defined from older patient cohorts. Direct RI studies are difficult, but indirect estimation may allow us to infer normative neonatal distributions from routinely collected clinical data.

OBJECTIVE

Assess the utility of indirect reference interval methods in estimating coagulation reference intervals in critically ill neonates.

METHODS

We analyzed first-in-life coagulation testing results from all patients admitted to a level IV neonatal intensive care unit between January 1, 2018, and January 1, 2024. Results obtained after transfusion of any blood product were excluded. Indirect RIs were estimated across gestational age groups using refineR and compared with currently reported intervals for patients less than 1 year of age.

RESULTS

Prothrombin times (PTs) and international normalized ratios (INRs) were available for 1128 neonates, while activated partial thromboplastin times (APTTs) were available for 790 neonates. The indirect RI was 10 to 25 seconds in preterm, 10 to 22 seconds in term, and 10 to 24 seconds in all neonates for PT; 0.7 to 2.1 in preterm, 0.8 to 1.8 in term, and 0.8 to 1.9 in all neonates for INR; and 25 to 68 seconds in preterm, 25 to 58 seconds in term, and 25 to 62 seconds in all neonates for APTT. Compared with our current intervals, the indirect RIs would flag 58% fewer PT, 43% fewer INR, and 17% fewer APTT results as abnormal.

CONCLUSION

Indirectly estimated RIs in neonates admitted to intensive care show substantial divergence from current, first-year-of-life RIs, leading to an abundance of abnormal flags. The associations between these flags and provider behavior, transfusion practice, or clinical outcomes are areas of future exploration.

Exposure Matching-Based Pediatric Dose Selection for Drugs with Renal Excretion - Lessons Learned from Pediatric Development of Direct Oral Anticoagulants

The pediatric clinical development programs of the direct oral anticoagulants (DOACs) edoxaban, rivaroxaban, and dabigatran have recently been completed, with apixaban close to the finish line. One common pharmacokinetic (PK) characteristic of these four DOACs is that renal excretion contributes 27% or more in their elimination, resulting in age-dependent drug clearance in both pediatric and adult subjects. Several lessons have been learned from adult exposure matching and pediatric dose selection for DOACs. The main goal of this tutorial is to provide an informed perspective on pediatric dose selection for renally excreted drugs, using these four DOACs as case examples. This tutorial is organized into seven steps: (1) consideration of age-related differences in disease and response to treatment; (2) consideration of age-related differences in drug absorption, distribution, metabolism, and excretion; (3) selection of the reference adult population and exposure for pediatric exposure matching; (4) prediction of pediatric clearance and pediatric dose selection based on data from young adults; (5) conduct and design of efficient pediatric PK and pharmacodynamic (PD) studies that inform dose selection; (6) assessment of exposure matching and dose adjustment using population PK simulation; (7) evaluation of the need for dose adjustment in pediatric sub-populations.

Global and regional burden of vaccine-induced thrombotic thrombocytopenia, 1969-2023: Comprehensive findings with critical analysis of the international pharmacovigilance database

OBJECTIVE

The scarcity of studies on vaccine-induced thrombosis and thrombocytopenia syndrome (TTS) limits the comprehensive understanding of vaccine safety on a global scale. Therefore, the objective of this study is to assess the global burden of vaccine-induced TTS, identify the vaccines most associated with it, and suggest clinical implications regarding vaccination.

METHODS

This study employed the World Health Organization international pharmacovigilance database, extracting records of vaccine-induced immune thrombotic thrombocytopenia from 1969 to 2023 (total reports, n > 130 million). Global reporting counts, reported odds ratios (ROR), and information components (IC) were calculated to identify the association between 19 vaccines and the occurrence of vaccine-induced TTS across 156 countries.

RESULTS

We identified 24 233 cases (male, n = 11 559 [47.7%]) of vaccine-induced TTS among 404 388 reports of all-cause TTS. There has been a significant increase in reports of vaccine-induced TTS events over time, with a noteworthy surge observed after 2020, attributed to cases of TTS associated with COVID-19 vaccines. Measles, mumps, and rubella (MMR) vaccines were associated with most TTS reports (ROR [95% confidence interval], 2.87 [2.75-3.00]; IC [IC0.25], 1.51 [1.43]), followed by hepatitis B (HBV, 2.23 [2.07-2.39]; 1.15 [1.03]), rotavirus diarrhea (1.95 [1.78-2.13]; 0.81 [0.53]), encephalitis (1.80 [1.50-2.16]; 0.84 [0.53]), hepatitis A (1.67 [1.50-1.86]; 0.73 [0.55]), adenovirus Type 5 vector-based (Ad5-vectored) COVID-19 (1.64 [1.59-1.68]; 0.69 [0.64]), pneumococcal (1.57 [1.49-1.66]; 0.65 [0.56]), and typhoid vaccines (1.41 [1.12-1.78]; 0.49 [0.11]). Concerning age and sex-specific risks, reports of vaccine-induced TTS were more associated with females and younger age groups. The age group between 12 and 17 years exhibited significant sex disproportion. Most of these adverse events had a short time to onset (days; mean [SD], 4.99 [40.30]) and the fatality rate was 2.20%, the highest rate observed in the age group over 65 years (3.79%) and lowest in the age group between 0 and 11 years (0.31%).

CONCLUSION

A rise in vaccine-induced TTS reports, notably MMR, HBV, and rotavirus diarrhea vaccines, was particularly related to young females. Ad5-vectored COVID-19 vaccines showed comparable or lower association with TTS compared to other vaccines. Despite the rarity of these adverse events, vigilance is essential as rare complications can be fatal, especially in older groups. Further studies with validated reporting are imperative to improve the accuracy of assessing the vaccine-induced TTS for preventive interventions and early diagnosis.

Whole blood: Total blood product ratio impacts survival in injured children

BACKGROUND

Some studies in both children and adults have shown a mortality benefit for the use of low titer group O whole blood (LTOWB) compared with component therapy for traumatic resuscitation. Although LTOWB is not widely available at pediatric trauma centers, its use is increasing. We hypothesized that in children who received whole blood after injury, the proportion of whole blood in relation to the total blood product resuscitation volume would impact survival.

METHODS

The trauma database from a single academic pediatric Level I trauma center was queried for pediatric (age <18 years) recipients of LTOWB after injury (years 2015-2022). Weight-based blood product (LTOWB, red blood cells, plasma, and platelet) transfusion volumes during the first 24 hours of admission were recorded. The ratio of LTOWB to total transfusion volume was calculated. The primary outcome was in-hospital mortality. Multivariable logistic regression model adjusted for the following variables: age, sex, mechanism of injury, Injury Severity Score, shock index, and Glasgow Coma Scale score. Adjusted odds ratio representing the change in the odds of mortality by a 10% increase in the LTOWB/total transfusion volume ratio was reported.

RESULTS

There were 95 pediatric LTOWB recipients included in the analysis, with median (interquartile range [IQR]) age of 10 years (5-14 years), 58% male, median (IQR) Injury Severity Score of 26 (17-35), 25% penetrating mechanism. The median (IQR) volume of LTOWB transfused was 17 mL/kg (15-35 mL/kg). Low titer group O whole blood comprised a median (IQR) of 59% (33-100%) of the total blood product resuscitation. Among patients who received LTOWB, there was a 38% decrease in in-hospital mortality for each 10% increase in the proportion of WB within total transfusion volume ( p < 0.001) after adjusting for age, sex, mechanism of injury, Injury Severity Score, shock index, and Glasgow Coma Scale score.

CONCLUSION

Increased proportions of LTOWB within the total blood product resuscitation was independently associated with survival in injured children. Based on existing data that suggests safety and improved outcomes with whole blood, consideration may be given to increasing the use of LTOWB over CT resuscitation in pediatric trauma resuscitation.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

Associations Between Clinical Factors and Postoperative Thrombosis in Pediatric Cardiac Surgery Patients: A Single-Center Retrospective Study

IMPORTANCE

Postoperative thrombosis is a significant complication in pediatric cardiac surgery patients, contributing to morbidity and mortality. Identifying clinical factors associated with thrombosis can improve patient outcomes by guiding early detection and intervention.

OBJECTIVES

This study aimed to assess factors associated with postoperative thrombosis or thromboembolism in pediatric patients under 12 months old who underwent surgery for congenital heart disease (CHD). Design, Setting, and Participants: This retrospective cohort study analyzed electronic medical records from pediatric patients admitted to the Pediatric Cardiovascular Intensive Care Unit (PCICU) at the German Paediatric Heart Center, Bonn, between March 1, 2020, and March 1, 2021. A total of 197 children under 12 months old who underwent cardiac surgery were included in the analysis.

MAIN OUTCOMES AND MEASURES

Thrombosis was diagnosed postoperatively using imaging modalities such as ultrasound, echocardiography, and computed tomography. The primary outcome was the incidence of thrombosis and its association with clinical factors such as age, central venous catheter (CVC) duration, CRP levels, and D-dimer levels.

RESULTS

Among 197 patients, the incidence of thrombosis was 8.63%, predominantly venous (70.6%). Initial associations were observed between thrombosis and younger age, lower body weight, higher hematocrit, cyanosis, longer central venous catheter (CVC) use, and elevated C-reactive protein (CRP) and d-dimer levels. Receiver operating characteristic analysis indicated a higher risk in patients with d-dimer levels above 5.47 mg/L. The stepwise multiregression analysis identified longer CVC duration in situ (β = 0.553; p < 0.001), higher CRP levels (β = 0.217; p = 0.022), and younger age at admission (β = -0.254; p = 0.006) as significant predictors of thrombosis. Decision tree analysis identified CVC use longer than 12.5 days and CRP levels above 118.01 mg/L as the most critical risk factors.

CONCLUSIONS AND RELEVANCE

Postoperative thrombosis is a notable risk in pediatric CHD patients, particularly in neonates. Prolonged CVC use and elevated CRP levels are critical risk factors. Routine monitoring of D-dimer and CRP levels, along with timely sonographic screening, can aid early thrombosis detection and intervention. Further research is warranted to optimize thrombosis prevention strategies in this population.

Comparison of standard and global hemostasis assays in cord and peripheral blood of newborns

BACKGROUND

Umbilical cord blood is used for the testing of various parameters in newborns. However, data on its applicability for hemostasis assays is insufficient.

OBJECTIVE

To evaluate whether umbilical cord blood can be used for standard tests, thromboelastometry and thrombodynamics for preterm and term newborns.

METHODS

187 newborns were included in the study. Blood was taken from the umbilical cord and by venipuncture of the newborn. Clotting times, fibrinogen, D-dimer, thromboelastometry and thrombodynamics were measured.

RESULTS

Clotting times and fibrinogen indicated a hypocoagulable shift, while thromboelastometry and thrombodynamics showed a hypercoagulable shift in hemostasis in umbilical cord blood compared to newborn blood. D-dimer indicated an enhanced process of thrombus lysis in newborn blood compared to cord blood. Collecting blood into a tube with the addition of a contact pathway inhibitor did not significantly change the global assay parameters in either umbilical cord blood or newborn blood. In the thrombodynamics assay, spontaneous clotting was detected but suppressed by the addition of a tissue factor inhibitor.

CONCLUSIONS

Hemostasis in cord and newborn blood differs for both global and standard tests. Hypercoagulability in newborns registered with the global assay thrombodynamics is associated with the presence of tissue factor in the blood.

IMPACT STATEMENT

1. We found a hypercoagulation shift in newborns compared with the adult references, possibly due to the presence of tissue factor in blood. 2. Blood coagulation is enhanced in cord blood compared with blood sampled from the vein of a newborn according to thromboelastometry and thrombodynamics assays. 3. Clotting times and fibrinogen concentrations in cord blood differ from these parameters in newborn blood. 4. Studying of the (patho)physiological features of hemostasis in newborns should consider differences in cord blood and vein sampled blood.

Deep Vein Thrombosis as the Presenting Sign in an Adolescent With New-Onset Type 2 Diabetes

Prothrombin G20210A mutation occurs in only 2% to 3% of the population, but usually does not become apparent unless the individual exhibits another risk factor for clotting. A risk factor such as hyperglycemia in the setting of diabetes mellitus may accelerate this clotting process, even at a very young age. In this case report, we discuss a 15-year-old boy presenting with left calf swelling and pain, found to have extensive deep vein thrombosis in the setting of hyperglycemia and a newly discovered prothrombin G20210A mutation. Venous thromboembolism in the setting of type 2 diabetes mellitus has not been described in children.

High-throughput microfluidic blood testing to phenotype genetically linked platelet disorders: an aid to diagnosis

Linking the genetic background of patients with bleeding diathesis and altered platelet function remains challenging. We aimed to assess how a multiparameter microspot-based measurement of thrombus formation under flow can help identify patients with a platelet bleeding disorder. For this purpose, we studied 16 patients presenting with bleeding and/or albinism and suspected platelet dysfunction and 15 relatives. Genotyping of patients revealed a novel biallelic pathogenic variant in RASGRP2 (splice site c.240-1G>A), abrogating CalDAG-GEFI expression, compound heterozygosity (c.537del, c.571A>T) in P2RY12, affecting P2Y12 signaling, and heterozygous variants of unknown significance in the P2RY12 and HPS3 genes. Other patients were confirmed to have Hermansky-Pudlak syndrome type 1 or 3. In 5 patients, no genetic variant was found. Platelet functions were assessed via routine laboratory measurements. Blood samples from all subjects and day controls were screened for blood cell counts and microfluidic outcomes on 6 surfaces (48 parameters) in comparison with those of a reference cohort of healthy subjects. Differential analysis of the microfluidic data showed that the key parameters of thrombus formation were compromised in the 16 index patients. Principal component analysis revealed separate clusters of patients vs heterozygous family members and control subjects. Clusters were further segregated based on inclusion of hematologic values and laboratory measurements. Subject ranking indicated an overall impairment in thrombus formation in patients carrying a (likely) pathogenic variant of the genes but not in asymptomatic relatives. Taken together, our results indicate the advantages of testing for multiparametric thrombus formation in this patient population.

The Hemostatic System in Newborns and the Risk of Neonatal Thrombosis

Newborns are the most vulnerable patients for thrombosis development among all children, with critically ill and premature infants being in the highest risk group. The upward trend in the rate of neonatal thrombosis could be attributed to progress in the treatment of severe neonatal conditions and the increased survival in premature babies. There are physiological differences in the hemostatic system between neonates and adults. Neonates differ in concentrations and rate of synthesis of most coagulation factors, turnover rates, the ability to regulate thrombin and plasmin, and in greater variability compared to adults. Natural inhibitors of coagulation (protein C, protein S, antithrombin, heparin cofactor II) and vitamin K-dependent coagulation factors (factors II, VII, IX, X) are low, but factor VIII and von Willebrand factor are elevated. Newborns have decreased fibrinolytic activity. In the healthy neonate, the balance is maintained but appears more easily converted into thrombosis. Neonatal hemostasis has less buffer capacity, and almost 95% of thrombosis is provoked. Different triggering risk factors are responsible for thrombosis in neonates, but the most important risk factors for thrombosis are central catheters, fluid fluctuations, liver dysfunction, and septic and inflammatory conditions. Low-molecular-weight heparins are the agents of choice for anticoagulation.

Anticoagulation-Free Pediatric Extracorporeal Membrane Oxygenation: Single-Center Retrospective Study

OBJECTIVES

To analyze hemorrhage and thrombosis data related to anticoagulation-free pediatric extracorporeal membrane oxygenation (ECMO).

DESIGN

Retrospective cohort study.

SETTINGS

High-volume ECMO single institution data.

PATIENTS

Children (0-18 yr) supported with ECMO (>24 hr) with initial anticoagulation-free period of greater than or equal to 6 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Utilizing consensus American Thoracic Society definitions for hemorrhage and thrombosis on ECMO, we evaluated thrombosis and associated patient and ECMO characteristics during anticoagulation-free period. Thirty-five patients met inclusion criteria from 2018 to 2021 having a median age (interquartile range [IQR]) of 13.5 months (IQR, 3-91 mo), median ECMO duration of 135 hours (IQR, 64-217 hr), and 964 anticoagulation-free hours. Increased RBC transfusion needs were associated with longer anticoagulation-free periods ( p = 0.03). We identified 20 thrombotic events: only four during the anticoagulation-free period and occurring in three of 35 (8%) patients. Compared with those without thrombotic events, anticoagulation-free clotting events were associated with younger age (i.e., 0.3 mo [IQR, 0.2-0.3 mo] vs 22.9 mo [IQR, 3.6-112.9 mo]; p = 0.02), lower weight (2.7 kg [IQR, 2.7-3.25 kg] vs 13.2 kg [5.9-36.4 kg]; p = 0.006), support with lower median ECMO flow rate (0.5 kg [IQR, 0.45-0.55 kg] vs 1.25 kg [IQR, 0.65-2.5 kg]; p = 0.04), and longer anticoagulation-free ECMO duration (44.5 hr [IQR, 40-85 hr] vs 17.6 hr [IQR, 13-24.1]; p = 0.008).

CONCLUSIONS

In selected high-risk-for-bleeding patients, our experience is that we can use ECMO in our center for limited periods without systemic anticoagulation, with lower frequency of patient or circuit thrombosis. Larger multicentered studies are required to assess weight, age, ECMO flow, and anticoagulation-free time limitations that are likely to pose risk for thrombotic events.

Outcomes in Pediatric Trauma Patients Who Receive Blood Transfusion

INTRODUCTION

Increased blood volumes, due to massive transfusion (MT), are known to be associated with both infectious and noninfectious adverse outcomes. The aim of this study was to assess the association between MT and outcomes in pediatric trauma patients, and, secondarily, determine if these outcomes are differential by age once MT is reached.

METHODS

Pediatric patients (ages 1-18 y old) in the ACS pediatric Trauma Quality Improvement Program (TQIP) database (2015-2018) who received blood were included. Patients were stratified by MT status, which was defined as blood product volume of 40 mL/kg within 24 h of admission (MT+) and compared to children who received blood products but did not meet the MT threshold (MT-). Defined MT + patients were matched 1:1 to MT-patients via propensity score matching of characteristics before comparisons. Adjusted logistic regression was performed on univariably significant outcomes of interest.

RESULTS

There were 2318 patients in the analytic cohort. Patients who received MT had higher rates of deep venous thrombosis (DVT) (2.5% versus 1.0%, P < 0.001), acute kidney injury (AKI) (1.5% versus 0.0%, P = 0.022), CLABSI (4.0% versus 2.0% P = 0.008), and severe sepsis (2.3% versus. 1.1%, P = 0.02). On logistic regression MT was an independent risk factor for these outcomes. There was no differential effect of MT on these outcomes based on age.

CONCLUSIONS

Outcomes associated with blood transfusion in pediatric trauma patients are low overall, but rates of DVT, AKI, CLABSI, and sepsis are higher in those who receive MT+ with no differences based on age.

Frailty score and outcomes of patients undergoing vascular surgery and amputation: A systematic review and meta-analysis

INTRODUCTION

Frailty is associated with adverse postoperative health outcomes, including increased mortality, longer length of stay, higher rehospitalization, and other complications. There are many frailty assessment tools are to assess the level of frailty in vascular surgery patients. The aim of this study was to perform a systematic review and meta-analysis to assess the association between the frailty levels described by different frailty scores and adverse postoperative health outcomes among hospitalized vascular surgery patients and patients undergoing amputation.

METHODS

Studies utilizing frailty scores and similar frailty assessment tools to describe frailty and investigate the association between frailty and health outcomes were searched. The primary outcomes of this study were in-hospital mortality, postdischarge mortality, length of hospital stay, rehospitalization, and discharge location. Additional outcomes included postoperative myocardial infarction, postoperative renal failure, cerebrovascular accident and stroke, comorbidities, and estimated glomerular filtration rate (eGFR) levels. Joanna Briggs Institute (JBI) Critical Appraisal Tools were used for quality assessment.

RESULTS

In total, 24 studies with 1,886,611 participants were included in the final analysis. The overall results found that higher in-hospital mortality and postdischarge mortality were significantly associated with frailty. Frailty was also found to be significantly associated with a longer length of hospital stay, higher rehospitalization, and higher likelihood of non-home discharge. In addition, the results also showed that frailty was significantly associated with all kinds of comorbidities investigated, except chronic kidney disease. However, lower eGFR levels were significantly associated with frailty.

CONCLUSION

Among patients who underwent all types of vascular surgery and those who underwent amputations, assessment of frailty was significantly associated with adverse postoperative outcomes and multiple comorbidities.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=336374, identifier CRD42022336374.

Novel Coagulation Test Detects Anticoagulation Resistance and Is Associated With Thrombotic Events in Pediatric Patients Requiring Extracorporeal Membrane Oxygenation

Bivalirudin, an IV direct thrombin inhibitor, and unfractionated heparin (UFH) are frequently used anticoagulants in the pediatric critical care setting. An accurate, specific, point-of-care test to quantify and detect anticoagulation resistance is not currently available. This study evaluates the ability of a rapid (< 10 min), micro-volume (< 50 uL) coagulation test to detect and quantify the anticoagulation effect of bivalirudin and UFH using a functional, clot time endpoint in pediatric critical care patients.

DESIGN

Single-site retrospective laboratory sample analysis and chart review.

SETTING

A 105-bed pediatric and cardiac ICUs delivering extracorporeal membrane oxygenation.

SUBJECTS

Forty-one citrated, frozen, biobanked plasma specimens comprising 21 with bivalirudin and 20 with UFH from 15 anticoagulated pediatric patients were analyzed. Thirteen patients were on extracorporeal membrane oxygenation, one had a submassive pulmonary embolism, and one was on a left ventricular assist device.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

A Clotting Time Score (CTS) was derived on each sample. The CTS detected patients that had developed a pathologic clotting event with 100% sensitivity and 82% specificity compared with prothrombin time with 25% sensitivity/76% specificity and activated partial thromboplastin time with 0% sensitivity/0% specificity. Additionally, the CTS detected subtherapeutic anticoagulation in response to UFH in patients that were clinically determined to be UFH resistant requiring alternative anticoagulation with bivalirudin.

CONCLUSIONS

The CTS appears to be a clinically valuable indicator of coagulation status in patients treated with either UFH or bivalirudin. Results outside of the therapeutic range due to inadequate dosing or anticoagulation resistance appeared to be associated with clot formation. CTS testing may reduce the risk of anticoagulation-related complications via the rapid identification of patients at high risk for pathologic thrombotic events.

Modern Aspects of Anticoagulation System Disorders Diagnosis in Children with Different Polymorphisms in Coagulation Genes. Initial Results

Background. Hemostatic system pathology is topical and poorly studied issue in pediatrics. One of the main causes of coagulation pathway disorders associated with thrombotic events is abnormality in various parts of the hemostatic system. Vascular accidents are commonly caused by anticoagulation system factors deficiency. Conventionally, thrombosis is a common event in adult patients, and there is no adequate attention to disorders of primary physiological anticoagulants system in children. More often acquired anticoagulant proteins deficiency develops in presence of various pathological conditions, especially after the past infectious diseases. All these diseases (thrombophilia, trombotic events, cardiovascular pathology, nervous system diseases, genetic diseases) can occur separately and in association with each other, plus clinical picture of coagulation events may be similar. Objective. The aim of the study is to evaluate changes in the physiological anticoagulants system in children with different pathologies who have polymorphic variants in coagulation genes and who had new coronavirus infection. Methods. The study included 33 children who had severe coronavirus infection in family clusters and had severe chronic pathology potentially associated with disorders of the coagulation system (nervous system damage, hypertrophic cardiomyopathy, hereditary monogenic syndromes, hemato-mesenchymal dysplasia syndrome). All children underwent complete examination including clinical examination, laboratory, and instrumental diagnostics. Results. Preliminary study results indicate significant incidence of polymorphic variants in coagulation genes (one third of children with various diseases from the study). Some children had decreased activity of anticoagulation system glycoproteins (from 6% to 36%) that confirmed the topicality of the examination of anticoagulation system factors deficiency and the need for further dynamic follow-up, as well as revealing of trombophilia predictors in children in selected target groups. Study on revealing anticoagulation system disorders and mutations in coagulation genes will predict the risk of thrombotic disorders. Conclusion. The obtained results have confirmed the significant role of the ongoing study for comprehensive assessment of hemostatic system disorders in children. That will allow us to optimize the approach to diagnosis and personalize the management strategy for patients with different chronic pathologies and disorders of the natural anticoagulants system. The study is currently ongoing.

Genetic Polymorphisms Associated with Prothrombin Time and Activated Partial Thromboplastin Time in Chinese Healthy Population

(1) Background: The purpose of this study was to evaluate the effect of gene polymorphisms on prothrombin time (PT) and activated partial thromboplastin time (APTT) in a healthy Chinese population. (2) Methods: A total of 403 healthy volunteers from a series of novel oral anticoagulants (NOACs) bioequivalence trials in China were included. Coagulation tests for PT and APTT were performed in the central lab at Peking University First Hospital. Whole-exome sequencing (WES) and genome-wide association analysis were performed. (3) Results: In the correlation analysis of PT, 105 SNPs from 84 genes reached the genome-wide significance threshold (p < 1 × 10−5). Zinc Finger Protein 594 (ZNF594) rs184838268 (p = 4.50 × 10−19) was most significantly related to PT, and Actinin Alpha 1 (ACTN1) was found to interact most with other candidate genes. Significant associations with previously reported candidate genes Aurora Kinase B (AURKB), Complement C5(C5), Clock Circadian Regulator (CLOCK), and Histone Deacetylase 9(HDAC9) were detected in our dataset (p < 1 × 10−5). PiggyBac Transposable Element Derived 2(PGBD2) rs75935520 (p = 4.49 × 10−6), Bromodomain Adjacent To Zinc Finger Domain 2A(BAZ2A) rs199970765 (p = 5.69 × 10−6) and Protogenin (PRTG) rs80064850 (p = 8.69 × 10−6) were significantly correlated with APTT (p < 1 × 10−5). The heritability values of PT and APTT were 0.83 and 0.64, respectively; (4) Conclusion: The PT and APTT of healthy populations are affected by genetic polymorphisms. ZNF594 and ACTN1 variants could be novel genetic markers of PT, while PRTG polymorphisms might be associated with APTT levels. The findings could be attributed to ethnic differences, and need further investigation.

Neonatal Platelets: Lower G12/13 Expression Contributes to Reduced Secretion of Dense Granules

Despite fully functional primary hemostasis, platelets of healthy neonates exhibit hypoaggregability and secretion defects, which may be adaptations to specific requirements in this developmental stage. The etiologies for reduced signal transduction vary with the type of agonist. The discovered peculiarities are lower receptor densities, reduced calcium mobilization, and functional impairments of G proteins. Reduced secretion of dense granules has been attributed to lower numbers of granules. Signaling studies with adult platelets have shown a regulating effect of the G_12/13 signaling pathway on dense granule secretion via RhoA. We comparatively analyzed secretion profiles using flow cytometry and expression levels of G_q, G_i, and G_12/13 using Western blot analysis in platelets from cord blood and adults. Furthermore, we evaluated Rho activation after in vitro platelet stimulation with thrombin using a pulldown assay. We observed a markedly reduced expression of the dense granule marker CD63 on neonatal platelets after thrombin stimulation. G_α12/13 expression was significantly decreased in neonatal platelets and correlated with lower Rho activation after thrombin stimulation. We conclude that lower expression of G_12/13 in neonatal platelets results in attenuated activation of Rho and may contribute to reduced secretion of dense granules after exposure to thrombin.

Coagulation Abnormalities and Clinical Complications in Children With SARS-CoV-2: A Systematic Review of 48,322 Patients

Given the limited information on the coagulation abnormalities of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in pediatric patients, we designed a systematic review to evaluate this topic. A comprehensive literature search was conducted for "SARS-CoV-2," "coagulopathy," and "pediatrics." Two authors independently screened the articles that the search returned for bleeding, thrombosis, anticoagulant and/or antiplatelet usage, and abnormal laboratory markers in pediatric patients with SARS-CoV-2, and the authors then extracted the relevant data. One hundred twenty-six publications were included. Thirty-four (27%) studies reported thrombotic complications in 504 patients. Thirty-one (25%) studies reported bleeding complications in 410 patients. Ninety-eight (78%) studies reported abnormal laboratory values in 6580 patients. Finally, 56 (44%) studies reported anticoagulant and/or antiplatelet usage in 3124 patients. The variety of laboratory abnormalities and coagulation complications associated with SARS-CoV-2 presented in this review highlights the complexity and variability of the disease presentation in infants and children.

Safety and immunogenicity of the ChAdOx1 nCoV-19 (AZD1222) vaccine in children aged 6-17 years: a preliminary report of COV006, a phase 2 single-blind, randomised, controlled trial

BACKGROUND

Vaccination of children and young people against SARS-CoV-2 is recommended in some countries. Scarce data have been published on immune responses induced by COVID-19 vaccines in people younger than 18 years compared with the same data that are available in adults.

METHODS

COV006 is a phase 2, single-blind, randomised, controlled trial of ChAdOx1 nCoV-19 (AZD1222) in children and adolescents at four trial sites in the UK. Healthy participants aged 6-17 years, who did not have a history of chronic respiratory conditions, laboratory-confirmed COVID-19, or previously received capsular group B meningococcal vaccine (the control), were randomly assigned to four groups (4:1:4:1) to receive two intramuscular doses of 5 × 10¹⁰ viral particles of ChAdOx1 nCoV-19 or control, 28 days or 84 days apart. Participants, clinical investigators, and the laboratory team were masked to treatment allocation. Study groups were stratified by age, and participants aged 12-17 years were enrolled before those aged 6-11 years. Due to the restrictions in the use of ChAdOx1 nCoV-19 in people younger than 30 years that were introduced during the study, only participants aged 12-17 years who were randomly assigned to the 28-day interval group had received their vaccinations at the intended interval (day 28). The remaining participants received their second dose at day 112. The primary outcome was assessment of safety and tolerability in the safety population, which included all participants who received at least one dose of the study drug. The secondary outcome was immunogenicity, which was assessed in participants who were seronegative to the nucleocapsid protein at baseline and received both prime and boost vaccine. This study is registered with ISRCTN (15638344).

FINDINGS

Between Feb 15 and April 2, 2021, 262 participants (150 [57%] participants aged 12-17 years and 112 [43%] aged 6-11 years; due to the change in the UK vaccination policy, the study terminated recruitment of the younger age group before the planned number of participants had been enrolled) were randomly assigned to receive vaccination with two doses of either ChAdOx1 nCoV-19 (n=211 [n=105 at day 28 and n=106 at day 84]) or control (n=51 [n=26 at day 28 and n=25 at day 84]). One participant in the ChAdOx1 nCoV-19 day 28 group in the younger age bracket withdrew their consent before receiving a first dose. Of the participants who received ChAdOx1 nCoV-19, 169 (80%) of 210 participants reported at least one solicited local or systemic adverse event up to 7 days following the first dose, and 146 (76%) of 193 participants following the second dose. No serious adverse events related to ChAdOx1 nCoV-19 administration were recorded by the data cutoff date on Oct 28, 2021. Of the participants who received at least one dose of ChAdOx1 nCoV-19, there were 128 unsolicited adverse events up to 28 days after vaccination reported by 83 (40%) of 210 participants. One participant aged 6-11 years receiving ChAdOx1 nCoV-19 reported a grade 4 fever of 40·2°C on day 1 following first vaccination, which resolved within 24 h. Pain and tenderness were the most common local solicited adverse events for all the ChAdOx1 nCoV-19 and capsular group B meningococcal groups following both doses. Of the 242 participants with available serostatus data, 14 (6%) were seropositive at baseline. Serostatus data were not available for 20 (8%) of 262 participants. Among seronegative participants who received ChAdOx1 nCoV-19, anti-SARS-CoV-2 IgG and pseudoneutralising antibody titres at day 28 after the second dose were higher in participants aged 12-17 years with a longer interval between doses (geometric means of 73 371 arbitrary units [AU]/mL [95% CI 58 685-91 733] and 299 half-maximal inhibitory concentration [IC₅₀; 95% CI 230-390]) compared with those aged 12-17 years who received their vaccines 28 days apart (43 280 AU/mL [95% CI 35 852-52 246] and 150 IC₅₀ [95% CI 116-194]). Humoral responses were higher in those aged 6-11 years than in those aged 12-17 years receiving their second dose at the same 112-day interval (geometric mean ratios 1·48 [95% CI 1·07-2·07] for anti-SARS-CoV-2 IgG and 2·96 [1·89-4·62] for pseudoneutralising antibody titres). Cellular responses peaked after a first dose of ChAdOx1 nCoV-19 across all age and interval groups and remained above baseline after a second vaccination.

INTERPRETATION

ChAdOx1 nCoV-19 is well tolerated and immunogenic in children aged 6-17 years, inducing concentrations of antibody that are similar to those associated with high efficacy in phase 3 studies in adults. No safety concerns were raised in this trial.

FUNDING

AstraZeneca and the UK Department of Health and Social Care through the UK National Institute for Health and Care Research.

Neonatal Myocardial Infarction: A Proposed Algorithm for Coronary Arterial Thrombus Management

BACKGROUND

Neonatal myocardial infarction is rare and is associated with a high mortality of 40% to 50%. We report our experience with neonatal myocardial infarction, including presentation, management, outcomes, and our current patient management algorithm.

METHODS

We reviewed all infants admitted with a diagnosis of coronary artery thrombosis, coronary ischemia, or myocardial infarction between January 2015 and May 2021.

RESULTS

We identified 21 patients (median age, 1 [interquartile range (IQR), 0.25-9.00] day; weight, 3.2 [IQR, 2.9-3.7] kg). Presentation included respiratory distress (16), shock (3), and murmur (2). Regional wall motion abnormalities by echocardiogram were a key criterion for diagnosis and were present in all 21 with varying degrees of depressed left ventricular function (severe [8], moderate [6], mild [2], and low normal [5]). Ejection fraction ranged from 20% to 54% (median, 43% [IQR, 34%-51%]). Mitral regurgitation was present in 19 (90%), left atrial dilation in 15 (71%), and pulmonary hypertension in 18 (86%). ECG was abnormal in 19 (90%). Median troponin I was 0.18 (IQR, 0.12-0.56) ng/mL. Median BNP (B-type natriuretic peptide) was 2100 (IQR, 924-2325) pg/mL. Seventeen had documented coronary thrombosis by cardiac catheterization. Seventeen (81%) were treated with intracoronary tPA (tissue-type plasminogen activator) followed by systemic heparin, AT (antithrombin), and intravenous nitroglycerin, and 4 (19%) were treated with systemic heparin, AT, and intravenous nitroglycerin alone. Nineteen of 21 recovered. One died (also had infradiaphragmatic total anomalous pulmonary venous return). One patient required a ventricular assist device and later underwent heart transplant; this patient was diagnosed late at 5 weeks of age and did not respond to tPA. Nineteen of 21 (90%) regained normal left ventricular function (ejection fraction, 60%-74%; mean, 65% [IQR, 61%-67%]) at latest follow-up (median, 6.8 [IQR, 3.58-14.72] months). Two of 21 (10%) had residual trivial mitral regurgitation. After analysis of these results, we present our current algorithm, which developed and matured over time, to manage neonatal myocardial infarction.

CONCLUSIONS

We experienced a lower mortality rate for infants with neonatal infarction than that reported in the literature. We propose a post hoc algorithm that may lead to improvement in patient outcomes following coronary artery thrombus.

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.

COVID-19: Thrombosis, thromboinflammation, and anticoagulation considerations

Vascular endothelial injury is a hallmark of acute infection at both the microvascular and macrovascular levels. The hallmark of SARS‐CoV‐2 infection is the current COVID‐19 clinical sequelae of the pathophysiologic responses of hypercoagulability and thromboinflammation associated with acute infection. The acute lung injury that initially occurs in COVID‐19 results from vascular and endothelial damage from viral injury and pathophysiologic responses that produce the COVID‐19–associated coagulopathy. Clinicians should continue to focus on the vascular endothelial injury that occurs and evaluate potential therapeutic interventions that may benefit those with new infections during the current pandemic as they may also be of benefit for future pathogens that generate similar thromboinflammatory responses. The current Accelerating COVID‐19 Therapeutic Interventions and Vaccines (ACTIV) studies are important projects that will further define our management strategies. At the time of writing this report, two mRNA vaccines are now being distributed and will hopefully have a major impact on slowing the global spread and subsequent thromboinflammatory injury we see clinically in critically ill patients.

Prophylactic antithrombotic management in adult and pediatric kidney transplantation: A systematic review and meta-analysis

BACKGROUND

RGT is a major cause for early graft loss after KTx. Although evidence-based recommendations are lacking, aP is often used to prevent RGT. This systematic review aimed to determine the effectiveness and safety of aP in adult and pediatric KTx recipients.

METHODS

MEDLINE, EMBASE, Cochrane Controlled Trials Register, conference proceedings, and electronic databases for trial registries were searched for eligible studies using search terms relevant to this review (April 21, 2020). The systematic review was carried out following the recommendations of the Cochrane Collaboration and the Prefered Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement.

RESULTS

Twelve studies comprising 2370 patients (adult = 1415, pediatric = 955) were included, of which three were RCTs. The overall risk for developing RGT was lower in the group with aP compared with the control group (RR 0.24, 95% confidence interval 0.12-0.49). The antithrombotic drugs used were heparin (7/12), acetylsalicylic acid (2/12), a combination of both (2/12), and dipyridamole (1/12) with a high variability in timing, dosing, and mode of application. Adverse effects were reported rarely, with minor bleeding as the main complication. The non-randomized studies had significant risks of bias in the domains of patient selection, confounder, and measurement of outcomes.

CONCLUSION

Based on pooled analysis, aP seems to reduce the risk of RGT in KTx. However, the reliability of these results is limited, as the quality of the available studies is poor and information on adverse effects associated with aP is scarce. Additional high-quality research is urgently needed to provide sufficient data supporting the use of aP in KTx.

Neonatal coagulopathies: A review of established and emerging treatments

Despite the relative frequency of both bleeding and clotting disorders among patients treated in the neonatal intensive care unit, few clear guidelines exist for treatment of neonatal coagulopathies. The study and treatment of neonatal coagulopathies are complicated by the distinct hemostatic balance and clotting components present during this developmental stage as well as the relative scarcity of studies specific to this age group. This mini-review examines the current understanding of neonatal hemostatic balance and treatment of neonatal coagulopathies, with particular emphasis on emerging treatment methods and areas in need of further investigative efforts.

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.