Pharmacokinetics, efficacy, and safety of LMWHs in venous thrombosis and stroke in neonates, infants and children

Venous Thromboembolism Prophylaxis in High-Risk Pediatric Trauma Patients

Importance

The indications, safety, and efficacy of chemical venous thromboembolism prophylaxis (cVTE) in pediatric trauma patients remain unclear. A set of high-risk criteria to guide cVTE use was recently recommended; however, these criteria have not been evaluated prospectively.

Objective

To examine high-risk criteria and cVTE use in a prospective multi-institutional study of pediatric trauma patients.

Design, Setting, and Participants

This cohort study was completed between October 2019 and October 2022 in 8 free-standing pediatric hospitals designated as American College of Surgeons level I pediatric trauma centers. Participants were pediatric trauma patients younger than 18 years who met defined high-risk criteria on admission. It was hypothesized that cVTE would be safe and reduce the incidence of VTE.

Exposures

Receipt and timing of chemical VTE prophylaxis.

Main Outcomes and Measures

The primary outcome was overall VTE rate stratified by receipt and timing of cVTE. The secondary outcome was safety of cVTE as measured by bleeding or other complications from anticoagulation.

Results

Among 460 high-risk pediatric trauma patients, the median (IQR) age was 14.5 years (10.4-16.2 years); 313 patients (68%) were male and 147 female (32%). The median (IQR) Injury Severity Score (ISS) was 23 (16-30), and median (IQR) number of high-risk factors was 3 (2-4). A total of 251 (54.5%) patients received cVTE; 62 (13.5%) received cVTE within 24 hours of admission. Patients who received cVTE after 24 hours had more high-risk factors and higher ISS. The most common reason for delayed cVTE was central nervous system bleed (120 patients; 30.2%). There were 28 VTE events among 25 patients (5.4%). VTE occurred in 1 of 62 patients (1.6%) receiving cVTE within 24 hours, 13 of 189 patients (6.9%) receiving cVTE after 24 hours, and 11 of 209 (5.3%) who had no cVTE (P = .31). Increasing time between admission and cVTE initiation was significantly associated with VTE (odds ratio, 1.01; 95% CI, 1.00-1.01; P = .01). No bleeding complications were observed while patients received cVTE.

Conclusions and Relevance

In this prospective study, use of cVTE based on a set of high-risk criteria was safe and did not lead to bleeding complications. Delay to initiation of cVTE was significantly associated with development of VTE. Quality improvement in pediatric VTE prevention may center on timing of prophylaxis and barriers to implementation.

Prophylactic Enoxaparin Against Catheter-Associated Thrombosis in Postoperative Cardiac Children: An Interrupted Time Series Analysis

OBJECTIVES

The effectiveness of pharmacologic prophylaxis against catheter-associated thrombosis in children is unclear. We evaluated the compliance and outcomes associated with a prophylactic enoxaparin protocol in postoperative cardiac children.

DESIGN

The protocol was implemented as a quality improvement initiative and then analyzed using interrupted time series method. Data collected from November 2014 to December 2018 were divided into preprotocol (period 1), protocol implementation (period 2), and protocol revision (period 3).

SETTING

A 12-bed academic pediatric cardiac ICU.

PATIENTS

Children less than or equal to 18 years old with congenital heart disease admitted postoperatively with central venous catheter in situ for greater than or equal to 1 day.

INTERVENTIONS

Before 2016, prophylactic enoxaparin was administered according to physician preference. In January 2016, an enoxaparin protocol was implemented with a goal anti-Xa range of 0.25-0.49 international units/mL. Protocol was revised in February 2017 to increase the starting dose by 25% for infants less than 1 year old.

MEASUREMENTS AND MAIN RESULTS

We analyzed 780 hospitalizations from 636 children. Median percentage of catheter-days on prophylactic enoxaparin was 33% (interquartile range [IQR], 23-47%), 42% (IQR, 30-51%), and 38% (IQR, 35-52%) in periods 1-3, respectively. Percentage of catheter-days on enoxaparin showed immediate increase of 90% (95% CI, 17-210%) between periods 1 and 2 and sustained increase of 2% (95% CI, 0.3-4%) between periods 2 and 3. Median rates of thrombosis per 1,000 catheter-days were 5.8 (IQR, 0-9.3), 3.8 (IQR, 0-12), and 0 (IQR, 0-5.3) in periods 1-3, respectively. Rate of thrombosis showed immediate decrease of 67% (95% CI, 12-87%) between periods 1 and 2 and sustained decrease of 11% (95% CI, 2-18%) between periods 1 and 3.

CONCLUSIONS

The temporal association between increase in percentage of catheter-days on enoxaparin and decrease in rate of thrombosis suggests the effectiveness of prophylactic enoxaparin.

APIXABAN'ın DOZA BAĞLI ANTİANJİYOJENİK POTANSİYELİ: Deneysel bir bakış

Amaç: Direkt oral antikoagülanlar (DOAK'lar), tromboembolizmin tedavisi ve önlenmesi için geleneksel tıbbi rejimlere iyi alternatiflerdir. Apixaban, bu yeni geliştirilen ilaçların daha popüler varyasyonlarından biridir. Antikoagülan potansiyelinin yanı sıra, olası hücresel etkiler gelecekteki çalışmaların konusu olmaya devam etmektedir. Bu çalışmanın amacı, korioallantoik membran (CAM) modelinde apiksaban'ın olası antianjiyogenik etkilerini araştırmaktı. Yöntem: Apixaban'ın 10-4, 10-5 ve 10-6 M konsantrasyonlarında ilaç peletleri hazırlandı ve yumurta inkübasyonunun dördüncü gününde korioallantoik membrana yerleştirildi. Sekizinci günde, membranların tüm vasküler yoğunlukları, bilinen bir monoklonal, insanlaştırılmış, vasküler endotelyal büyüme faktörü inhibitörü olan 10-6 M'lik bir bevacizumab konsantrasyonu ile karşılaştırıldı. Sonuçlar: 10-4 M apiksaban konsantrasyonunun, bevacizumabınkine benzer güçlü bir antianjiyogenik potansiyele sahip olduğunu bulduk. Bununla birlikte, daha düşük bir apiksaban dozunda (10-5 M, 10-6 M) orta düzeyde antianjiyogenik potansiyel vardı. Daha yüksek antianjiyogenik potansiyel dozlarının (10-4 M konsantrasyon) daha düşük dozlarda apiksaban (10-5 M, 10-6 M) ile karşılaştırılması, önemli istatistiksel farklılıklar ortaya çıkardı (p < 0.05). Sonuç: Sonuçlarımız, yüksek doz apiksaban'ın güçlü antianjiyogenik potansiyele sahip olduğunu göstermektedir. Bu etkinin kesin mekanizması bilinmemektedir. Bu pilot sonuçlar, DOAK'lara yeni bir bakış elde etmek için daha ileri çalışmalarla doğrulanmalıdır.

Prophylaxis of Venous Thromboembolism in Children: A Systematic Review

Venous thromboembolism (VTE) in children is a rare but serious event. Current guidance on pharmacological thromboprophylaxis in children is mostly based on adult studies and expert opinions. The aim of this systematic review was to examine under which conditions children (age ≤ 18 years) would benefit from pharmacological thromboprophylaxis with low molecular weight heparin or unfractionated heparin. Eligible studies included children, who did not receive pharmacological thromboprophylaxis as comparator, and VTE events were radiologically verified. MEDLINE and Embase were searched up to October 3, 2021. Ten studies were included presenting data for 976 children receiving pharmacological thromboprophylaxis. We divided the studies into three categories based on the population studied: children in the intensive care unit (n = 2), children with fractures and/or undergoing surgery (n = 5), and children with systemic disease (n = 3). A lower incidence of VTE was found when pharmacological thromboprophylaxis was used compared with no prophylaxis in children in intensive care unit with central venous catheter and mechanical ventilation (7/27 vs. 13/24), children in the intensive care unit admitted after trauma with a very high risk of VTE based on several risk factors (0/21 vs. 13/96), and children with acute lymphoblastic leukemia treated with L-asparaginase concomitant with steroid and presence of central venous catheter (0/82 vs. 8/121). Pharmacological thromboprophylaxis was not associated with an increased bleeding risk. In conclusion, pharmacological thromboprophylaxis in children is sparsely investigated. Only children with several risk factors for VTE are likely to benefit from pharmacological thromboprophylaxis.

New Anticoagulants in Neonates, Children, and Adolescents

Thrombotic events are an increasing challenge in pediatrics. Standard-of-care anticoagulants for pediatric thrombosis have several disadvantages which could be overcome by using direct oral anticoagulants (DOACs). Until recently, there was not enough evidence from clinical trials to recommend for or against the use of any of the four DOACs in children with thrombosis. In this literature review, we looked at the latest clinical trials in this field. On clinicaltrials.gov, we found 13 current studies with published results. For two of the four DOACs, namely dabigatran and rivaroxaban, we found successful phase III studies which led to the approval for the use in children. The results of these pivotal phase III studies allow to finally recommend rivaroxaban and dabigatran for the prophylaxis and treatment of thrombotic events in children.

Effectiveness and Safety of Nadroparin Therapy in Preterm and Term Neonates with Venous Thromboembolism

INTRODUCTION

Optimal neonatal nadroparin dosages to treat venous thromboembolism (VTE) are unknown.

OBJECTIVE

To evaluate therapeutic nadroparin dosages to reach therapeutic target ranges (TTR: 0.5-1.0 International Unit (IU)/mL) and the effectiveness and safety of nadroparin in neonatal VTE.

METHODS

Retrospective study including neonates with VTE on nadroparin in a tertiary center between 2007 and 2018. Two groups were distinguished: neonates before (group 1) and after (group 2) switch to higher starting dosages in 2014.

RESULTS

Sixty-one neonates (44 preterm, 17 term) with 64 VTEs were included. TTR was reached in 32/64 (50%) VTEs (group 1: 35.7%; group 2: 61.1%). Median nadroparin dosage to reach TTR was 197 (97.9-330.3) IU/kg/12 h. No therapy-related deaths occurred. Recurrent VTE developed in 6 (9.8%) neonates. Complete clot resolution was observed in 31/41 (75.6%) VTEs. TTR was reached in 58.1% VTEs with complete clot resolution. No major bleeding occurred. Non-major clinically relevant bleedings occurred in 3/64 (4.7%) VTEs, consisting of large hematomas due to the use of subcutaneous catheters.

CONCLUSIONS

High nadroparin dosages are needed to reach TTR in neonates, which seem to be safe. Clot resolution may occur without reaching TTR. Subcutaneous catheters may cause important bleeding complications.

[Enoxaparin and tinzaparin in pediatrics: Impact of recommendation on prescription quality and anti-Xa levels]

OBJECTIVES

A protocol has been written and distributed in May 2017 to all prescribers in a pediatric hospital to standardize and to secure the prescriptions of enoxaparin and tinzaparin considered as two high risk medications. The aim of this study is to evaluate the impact of the protocol on those prescriptions in a pediatric population.

METHODS

This is a monocentric retrospective study comparing prescriptions of this two low-molecular-weight heparins for patients under 18 years old in 2016 and 2018, thus before and after the protocol redaction.

RESULTS

In 2016, 2246 prescriptions of enoxaparin and tinzaparin were analyzed for 627 patients. Among them, 142 (22.6%) patients have had at least one anti-Xa level dosed. On the other hand, in 2018, 2061 prescriptions were written for 628 patients including 96 (15.3%) who have had at least one anti-Xa level dosed. The conformity rate of the first dose in IU/kg/administration of the first enoxaparin prescription goes from 36.3% before protocol to 52.1% after (P=0.03*). Concerning tinzaparin, the conformity rate goes from 69.2% to 83.3%. (P=0.19). The rate of first anti-Xa level in the range 0.4 to 1.2 IU/ml increase between 2016 and 2018 from 27.7% to 43.8% (P<0.001*).

CONCLUSION

This protocol enabled to improve the quality of prescriptions in terms of: dosage written in IU/kg/administration, frequency of administration, dilution conformity, and result of the first anti-Xa level. Some efforts must be made in writing the dose in IU not in mg or ml.

Concordance of Identified Cases of Pediatric HA-VTE with American College of Physicians and Cincinnati Children's Hospital HA-VTE Prophylaxis Guidelines Over a 10-Year Period

Objective: Our aim is to (1) ascertain the proportion of pediatric patients at a tertiary hospital in Western Massachusetts over a 10-year period with hospital-acquired venous thromboembolism (VTE) of particular characteristics and (2) determine whether ACCP or Cincinnati Children’s guidelines would have recommended VTE prophylaxis in these patients. Setting: Urban teaching hospital in the United States. Participants: Data from 98 477 pediatric hospital admissions (roughly 10 000 admission per year) from 2008 to 2017 were reviewed. There were a total of 177 VTE cases identified. Outcome measures: Hospital-acquired venous thromboembolism (including deep venous thrombosis and pulmonary embolism). Result: 177 charts were extracted that carried the diagnosis of VTE based on ICD-9 and ICD-10 codes over a 10-year-period. Among these patients, 34 (19%) met the inclusion criteria for HA-VTE; 5 (16%) would qualify for prophylaxis according to ACCP and 7 (21%) according to Cincinnati Children’s guideline. The most common age group to have a VTE was infants under 1 year of age (41%), and the most common characteristic was the presence of a central line (82%). Age outside of the recommended range was the sole reason that excluded patients from prophylaxis qualification per Cincinnati Children’s. Conclusion: HA-VTE carries increased morbidity and mortality. Although recognition and prevention of HA-VTE in adult populations are routine, prophylaxis for pediatric HA-VTE is not commonly practiced. This may be due to paucity of strong evidence supporting prophylaxis and the challenge of identifying risk factors for HA-VTE. Our results suggest that published guidelines recommend prophylaxis in only a minority of pediatric patients who would have subsequently developed HA-VTE. Further modification and validation of current guidelines are needed to effectively prevent pediatric HA-VTE.

FondaKIDS III: A long-term retrospective cohort study of fondaparinux for treatment of venous thromboembolism in children

BACKGROUND

The incidence of venous thromboembolism (VTE) and use of anticoagulation are rising in children, but treatment options remain limited. As a newer anticoagulant, fondaparinux may be a safe and effective alternative with the benefit of once-daily dosing, but there is relatively little data supporting its use.

PROCEDURE

This retrospective cohort study describes the long-term dosing, efficacy, and safety of fondaparinux for treatment of VTE in children at a single institution. The study included children <18 years old treated with fondaparinux for VTE between 2008 and 2018. Descriptive statistics were used to present the findings.

RESULTS

A total of 277 patients were identified and analyzed in this study. Seventy-six percent of patients reached therapeutic levels with 0 or 1 dose adjustments over a median treatment duration of 93 days. Of the patients included in the efficacy analysis, 91% of patients had improvement in their clot status, including 69% (160/233) with complete resolution and 22% (53/233) with partial resolution. Twenty-six patients (11%) had VTE recurrence, but only seven (3%) of the new thrombi developed while on fondaparinux. Major bleeding occurred in seven patients (2.5%), primarily in patients with underlying medical conditions with increased bleeding risk. Minor bleeding occurred in 53 patients (19%).

CONCLUSIONS

This study demonstrates the stable long-term pediatric dosing of fondaparinux with similar efficacy and safety when compared to other anticoagulants. Given its advantages, fondaparinux can be considered a reasonable alternative for treatment of VTE in children.

Challenges and Opportunities in the Pharmacological Treatment of Acute Venous Thromboembolism in Children

Venous thromboembolism (VTE) is an important but historically under-recognized problem in pediatrics, with an incidence concentrated in hospitalized children. A number of specific VTE diseases with discrete triggers have been described, but the most common pediatric trigger is the presence of central venous access devices. VTE diseases, though heterogenous in etiology, are linked by the common therapeutic strategies shared by their management. Historically, the most commonly used drug therapies have been unfractionated heparin, low-molecular-weight heparins, and vitamin K antagonists, based on extrapolation from adult data rather than any specific pediatric trials. Although these widely used drugs appear safe and effective in expert hands, the historical lack of pediatric data is problematic in view of the recognized significant differences between children and adults with regards to hemostatic physiology, VTE etiology, and drug pharmacokinetics. The increasing adult usage of novel VTE pharmacotherapies such as direct oral anticoagulants (DOACs) has led to considerable interest in exploring the pediatric applications of these newer drugs. This review summarizes the advantages and disadvantages of existing VTE pharmacotherapies and outlines emerging novel pediatric VTE therapies, particularly DOACs, within the context of the current pediatric trial landscape.

A bibliometric analysis of publications on venous thromboembolism in children from 1988 to 2019

INTRODUCTION

Venous thromboembolism (VTE) in children not only imposes a heavy burden on the medical resources and economy of the society, but also seriously affects the growth and development of children, even threaten children's lives. A large number of publications have been performed in this field in recent years. In this bibliometric analysis, publications on VTE in children were examined and analyzed to explain the present research hotspots.

METHODS

Articles related to VTE in children published in the PubMed database from 1988 to June 18, 2019 were selected as the research sample. BICOMB software was used to retrieve the annual publications, journals, journal source countries and the high-frequency major medical subject headings (MeSH) terms on the articles. Then, the co-word matrix was constructed by BICOMB using the selected high-frequency MeSH terms. Next, gCLUTO software was used to analyze the matrix by double clustering and visual analysis in a strategy of hotspot identification. In addition, CiteSpace software was used to perform the knowledge map of co-authors to explore the core authors.

RESULTS

One thousand seven hundred seventy-nine articles on VTE in children were obtained. Seven hundred ninety academic journals distributed in 58 countries have published articles on VTE in children, and the developed countries and the United States were the major force in the journal source countries. Nowak-Göttl U occupied an important position in this field. We constructed a co-word matrix composing of 37 high-frequency MeSH terms, generated visual matrix and visual hill, and classified the hot-spots into 5 aspects based on 8 categories.

CONCLUSION

The results show that the research trend of children's VTE has been increasing gradually, and the sound achievement has been obtained in these hotspots in relation to the area of inherited thrombophilia, prevention and control, treatment, diagnosis, prevalence, risk factors, and complication study. However, there is a lack of communication and cooperation in this field, and the gap of national and regional research results is huge. To sum up, this study provides evidence and guidance for researchers, clinicians, and educators.

Thrombotic risk in children undergoing orthopedic surgery

Children are physiologically protected against venous thromboembolism (VTE). Specific triggering events or contributing factors have been identified in the majority of reported cases, which differs from the adult pathology where 50% of the thromboses are considered "idiopathic". This is a rare disease in children with an estimated frequency of less than 1/1000. The risk is highest in neonates, then decreases and increases again around 13 years to reach the same level as adults at 16 years. The risk of VTE is clearly higher in certain situations: significant trauma, prolonged immobilization, central venous catheter, stay in intensive care unit, inherited thrombophilia, cancer, obesity, oral contraceptives, etc. Thromboprophylaxis should not be used systematically, even in adolescents. Proper hydration and early mobilization form the basis of mechanical thromboprophylaxis. A prescription is only given after careful analysis of the child's risk factors and the orthopedic context. Thrombotic risk assessment scores - which are based on expert opinion and large VTE registers but have not been evaluated in clinical studies - are currently the most reliable method to evaluate the thrombotic risk in children and to prescribe thromboprophylaxis. Low-molecular weight heparin are the most commonly used thromboprophylaxis agents in children, with good tolerance and efficacy.

Risk factors for venous thromboembolic events in pediatric surgical patients: Defining indications for prophylaxis

BACKGROUND

Venous thromboembolism (VTE) in pediatric surgical patients is a rare event. The risk factors for VTE in pediatric general surgery patients undergoing abdominopelvic procedures are unknown.

STUDY DESIGN

The American College of Surgeon's National Surgical Quality Improvement Program-Pediatric (NSQIP-P) database (2012-2015) was queried for patients with VTE after abdominopelvic general surgery procedures. Patient and operative variables were assessed to identify risk factors associated with VTE and develop a pediatric risk score.

RESULTS

From 2012-2015, 68 of 34,813 (0.20%) patients who underwent abdominopelvic general surgery procedures were diagnosed with VTE. On multivariate analysis, there was no increased risk of VTE based on concomitant malignancy, chemotherapy, inflammatory bowel disease, or laparoscopic surgical approach, while a higher rate of VTE was identified among female patients. The odds of experiencing VTE were increased on stepwise regression for patients older than 15 years and those with preexisting renal failure or a diagnosis of septic shock, patients with American Society of Anesthesia (ASA) classification ≥ 2, and for anesthesia time longer than 2 h. The combination of age > 15 years, ASA classification ≥ 2, anesthesia time > 2 h, renal failure, and septic shock was included in a model for predicting risk of VTE (AUC = 0.907, sensitivity 84.4%, specificity 88.2%).

CONCLUSION

VTE is rare in pediatric patients, but prediction modeling may help identify those patients at heightened risk. Additional studies are needed to validate the factors identified in this study in a risk assessment model as well as to assess the efficacy and cost-effectiveness of prophylaxis methods.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Management of Paediatric Ulcerative Colitis, Part 2: Acute Severe Colitis-An Evidence-based Consensus Guideline From the European Crohn's and Colitis Organization and the European Society of Paediatric Gastroenterology, Hepatology and Nutrition

BACKGROUND AND AIM

Acute severe colitis (ASC) is one of the few emergencies in pediatric gastroenterology. Tight monitoring and timely medical and surgical interventions may improve outcomes and minimize morbidity and mortality. We aimed to standardize daily treatment of ASC in children through detailed recommendations and practice points which are based on a systematic review of the literature and consensus of experts.

METHODS

These guidelines are a joint effort of the European Crohn's and Colitis Organization (ECCO) and the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN). Fifteen predefined questions were addressed by working subgroups. An iterative consensus process, including 2 face-to-face meetings, was followed by voting of the national representatives of ECCO and all members of the Paediatric Inflammatory Bowel Disease (IBD) Porto group of ESPGHAN (43 voting experts).

RESULTS

A total of 24 recommendations and 43 practice points were endorsed with a consensus rate of at least 91% regarding diagnosis, monitoring, and management of ASC in children. A summary flowchart is presented based on daily scoring of the Paediatric Ulcerative Colitis Activity Index. Several topics have been altered since the previous 2011 guidelines and from those published in adults.

DISCUSSION

These guidelines standardize the management of ASC in children in an attempt to optimize outcomes of this intensive clinical scenario.

Can thrombophilia predict recurrent catheter-related deep vein thrombosis in children?

Thrombophilia was not predictive of recurrent catheter-related deep vein thrombosis in children. Young age at the time of catheter insertion and lack of administration of anticoagulation were predictive of recurrent events.

Intramural Bowel Hematoma Presenting as Small Bowel Obstruction in a Patient on Low-Molecular-Weight Heparin

There is increasing use of low-molecular-weight heparin (LMWH) for treatment of pediatric thromboembolic disease as it has been shown to be safe and effective. It has several advantages over unfractionated heparin, such as reduced need for monitoring, easier route of administration, decreased risk of heparin-induced thrombocytopenia, and lack of drug-drug interactions. Nevertheless, LMWH still poses a bleeding risk as with any anticoagulant therapy. We present the case of a 4-year-old boy who was placed on LMWH for a catheter-related deep venous thrombosis in the setting of intractable seizures and subsequently developed a small bowel obstruction secondary to a suspected intussusception. He underwent exploratory laparotomy and was found to have an intramural bowel hematoma. Prior to this bleed, the patient had been monitored daily, and his anti-Xa levels were found to be in the therapeutic range. This case highlights the need for a high index of suspicion for spontaneous bleeding even in the setting of therapeutic anti-Xa levels.

Rationale and design of a phase III safety trial of idarucizumab in children receiving dabigatran etexilate for venous thromboembolism

BACKGROUND

The incidence of venous thromboembolism (VTE) in children has been increasing. Anticoagulants are the mainstay of treatment but are associated with bleeding events that may be life-threatening. Idarucizumab is a fragment antigen-binding (fab) that provides immediate, complete, and sustained reversal of dabigatran's anticoagulant effects in adults.

OBJECTIVE AND METHODS

This phase III, open-label, single-arm, multicenter, multinational trial will assess the safety of idarucizumab in children participating in two ongoing trials investigating dabigatran etexilate. Eligible patients will be children with VTE (aged 0-≤18 years; n = ~5) with life-threatening or uncontrolled bleeding (group A), and children who require emergency surgery/urgent procedures for a condition other than bleeding (group B). Patients will receive idarucizumab up to 5 g as two consecutive intravenous infusions over 5-10 minutes each, as two 10-15-minute drips or as two bolus injections (15 minutes apart) and will be monitored for 30 days. The primary endpoint will be the safety of idarucizumab assessed by the occurrence of drug-related adverse events (including immune reactions) and all-cause mortality. Secondary endpoints will be the reversal of dabigatran anticoagulant effects assessed by changes in diluted thrombin time and ecarin clotting time, time to achieve complete reversal and the duration of the reversal and bleeding severity (group A). The formation of antidrug antibodies at 30 days post-dose and cessation of bleeding will also be assessed.

CONCLUSION

This study will report the safety of idarucizumab in children with VTE who require rapid reversal of the anticoagulant effects of dabigatran. Clinical trial registration: NCT02815670.

Duration of anticoagulant therapy in pediatric venous thromboembolism: Current approaches and updates from randomized controlled trials

INTRODUCTION

Compared with the incidence of venous thromboembolism in the adult population, pediatric VTE is rare. Yet, recent data suggest that the incidence of VTE in children is increasing, and little is known about the optimal duration of anticoagulation in pediatrics. Areas covered: This review summarizes current evidence-based adult recommendations and associated clinical trials from which current guidelines on the duration of anticoagulation in children have been extrapolated. It also discusses pediatric expert consensus-based guidelines and current pediatric clinical trials on duration of therapy in pediatric VTE. Expert commentary: The vast majority of pediatric VTE are provoked, and evidence on duration of anticoagulation for pediatric VTE is highly limited, but suggests that a maximum duration of 3 months is reasonable for most patients with provoked VTE, whereas longer duration is likely appropriate for unprovoked VTE. Whether shorter duration than 3 months is optimal for pediatric provoked VTE is as yet unclear. Results from the multinational randomized controlled trial studying the duration of anticoagulant therapy for provoked VTE in patients <21 years old (Kids-DOTT) will be critical to inform the future standard of care in pediatric VTE treatment.

Evaluation of the age-dependent dosing recommendations for the administration of daily tinzaparin in children with thrombosis

Essentials The once-daily dosing of tinzaparin provides an advantage over other low molecular weight heparins. The recommended age-dependent doses of tinzaparin in children have not previously been validated. Once-daily administration of tinzaparin is a safe and effective treatment of childhood thrombosis. Recommended doses are appropriate but monitoring may be required due to inter-individual variation.

SUMMARY

Background The recommended starting doses of tinzaparin for the treatment of thrombosis in children have not previously been validated. There are few data to support the efficacy and safety of once-daily tinzaparin dosing in children with thrombosis. Objectives To investigate the use of tinzaparin for the treatment of childhood thrombosis, and to evaluate the age-dependent dosing recommendations and define outcomes in terms of efficacy and safety. Methods This was a retrospective cohort study of children aged 0 to < 16 years treated for thrombosis at a large teaching hospital in the UK between 2008 and 2015. Medical records were reviewed to evaluate tinzaparin dosing, anti-activated factor X (FXa) levels, and patient outcomes. Results Seventy-nine children were identified as having received tinzaparin. Dosing information was available for 57. Younger children required higher doses to reach a therapeutic level. The therapeutic dose requirement varied within age groups, supporting the use of anti-FXa monitoring. Over a median follow-up of 35 months, there were 13 (16%) bleeding episodes (two major; seven clinically relevant but non-major; and four minor). There were two (3%) recurrent episodes of thrombosis. Children were treated for a median duration of 3 months, and the majority (86%) remained on tinzaparin for the duration of their anticoagulant therapy. Conclusion Once-daily tinzaparin is a safe and effective treatment for childhood thrombosis, with rates of recurrence and bleeding similar to those for other anticoagulants used in children. The recommended starting doses are appropriate, but anti-FXa monitoring may be required, owing to interindividual variability in the therapeutic dose requirement.

Reduced dosing of enoxaparin for venous thromboembolism in overweight and obese adolescents: a single institution retrospective review

BACKGROUND

The global obesity epidemic has created new challenges, including venous thromboembolisms (VTE) in obese adolescents. The data on whether to reduce the dose of low-molecular heparin in obese adults is conflicting, and information on adolescent patients is scarce.

OBJECTIVES

Our primary goal was to describe dosing, anti-Xa levels, and outcomes of overweight and obese adolescents who received reduced doses of enoxaparin at the initiation of therapy. The secondary goal was to compare their outcomes to overweight and obese adolescents who received standard 1 mg/kg dosing to determine if future trials for dose reduction are warranted.

PATIENTS/METHODS

We performed a retrospective cohort study of overweight and obese patients between the ages of 12 and 18 years old diagnosed with VTE who were treated with reduced dosing (RD) of enoxaparin, comparing their dosing, anti-Xa levels, and outcomes to overweight and obese adolescents who received standard dosing (SD).

RESULTS

RD patients (n=19) achieved therapeutic mean initial anti-Xa levels that were similar to SD patients (n=11). Of the RD patients, 53% did not require dose adjustments during treatment. Two RD patients had thrombus progression. A total of 25 patients ultimately completed therapy with RD.

CONCLUSIONS

Future trials are warranted to evaluate the efficacy and safety of reduced dosing of enoxaparin to treat overweight and obese adolescents with VTE.

Pediatric Hospital Acquired Venous Thromboembolism

Pediatric hospital acquired venous thromboembolism (HA-VTE) is an increasing problem with an estimated increase from 5.3 events per 10,000 pediatric hospital admissions in the early 1990s to a current estimate of 30-58 events per 10,000 pediatric hospital admissions. Pediatric HA-VTE is associated with significant morbidity and mortality. The etiology is multifactorial but central venous catheters remain the predominant risk factor. Additional HA-VTE risk factors include both acquired (recent surgery, immobility, inflammation, and critical illness) and inherited risk factors. Questions remain regarding the most effective method to assess for HA-VTE risk in hospitalized pediatric patients and what preventative strategies should be implemented. While several risk-assessment models have been published in pediatric patients, these studies have limited power due to small sample size and require prospective validation. Potential thromboprophylactic measures include mechanical and pharmacologic methods both of which have associated harms, the most significant of which is bleeding from anticoagulation. Standard anticoagulation options in pediatric patients currently include unfractionated heparin, low molecular weight heparin, or warfarin all of which pose a monitoring burden. Ongoing pediatric studies with direct oral anticoagulants could potentially revolutionize the prevention and treatment of pediatric thrombosis with the possibility of a convenient route of administration and no requirement for monitoring. Further studies assessing clinical outcomes of venous thromboembolism (VTE) prevention strategies are critical to evaluate the effectiveness and harm of prophylactic interventions in children. Despite HA-VTE prevention efforts, thrombotic events can still occur, and it is important that clinicians have a high clinical suspicion to ensure prompt diagnosis and treatment to prevent further associated harms.

[Haemostatic disorders in children]

Haemorrhagic and thrombotic events occur in both children and adults. The underlying causes are congenital or acquired disorders. In contrast to haemorrhagic disorders, inherited thrombotic disorders nearly exclusively in association with additional external risk factors lead to thrombotic events predominantly during the newborn period and adolescence. It is necessary to be aware of age-specific properties of coagulation in order to correctly interpret clinical and laboratory findings and to provide optimal care for children with haemorrhagic and thrombotic complications.

Acute Limb Ischemia in Pediatric Population Secondary to Peripheral Vascular Cannulation

Introduction:

In this article, we discuss published literature on the management of pediatric patients with acute limb ischemia and also present our center’s experience.

Results:

Literature review suggests that in the absence of imminent risk of limb loss, noninterventional management with anticoagulants and systemic thrombolysis is preferable and associated with better clinical outcomes than surgery such as reduced per operative morbidity and mortality. In selected more severe cases, surgery may be required. We propose an algorithm for improved clinical outcomes based on the published literature and the American College of Chest Physicians’ recommendations for antithrombotic management in the pediatric population.

Conclusion:

Literature review suggests an inverse relationship between age and surgical success, particularly in preschool pediatric population. Conservative management as a preliminary strategy seems most beneficial. It is hoped that the proposed intercalated algorithm of medical and surgical management of these patients can further improve clinical outcomes.

Preclinical safety evaluation of low molecular weight heparin-deoxycholate conjugates as an oral anticoagulant

The preclinical safety of a newly developed oral anticoagulant, the low molecular weight heparin-deoxycholate conjugate (OH09208), was evaluated by a comprehensive evaluating program in compliance with standard guidelines. The single dose oral toxicity study in rats receiving 2000 and 5000 mg kg(-1) of OH09208 did not reveal any mortality, unusual body weight changes or necropsy findings. The results of the 4-week oral toxicity study with a 4-week recovery program in rats receiving OH09208 in doses of 100, 300 and 1000 mg kg(-1) day(-1) did not reveal any mortality, or indicate any unusual clinical signs, or show any toxicokinetic relationships to the administration of OH09208. Although the increase in liver enzymes in one male dog treated with 300 mg kg(-1) day(-1) and one female dog treated with 1000 mg kg(-1) day(-1) could not be excluded from the effect of the test substance, no other toxicologically significant changes were observed in the 4-week oral toxicity study with a 4-week recovery in beagle dogs. Thus, while the no-observed-adverse-effect level value from the 4-week study in both male and female rats was 1000 mg kg(-1) day(-1), those from the 4-week study in male and female beagle dogs were 300 and 1000 mg kg(-1) day(-1), respectively. Furthermore, OH09208 did not induce anaphylactic reactions in guinea pigs, micronucleated bone marrow cells in male ICR mice, chromosomal aberration in Chinese hamster lung cell lines, bacterial reverse mutation, and any abnormalities in hERG current assay, mouse central nervous system and dog cardiovascular studies. Overall, there were no unexpected toxicities in this preclinical study that might have precluded the safe administration of OH09208 to humans.

Anticoagulant therapy in pediatrics

Thromboembolic episodes are disorders encountered in both children and adults, but relatively more common in adults. However, the occurrence of venous thromboembolism and use of anticoagulants in pediatrics are increasing. Unfractionated Heparin (UH) is used as a treatment and prevention of thrombosis in adults and critically ill children. Heparin utilization in pediatric is limited by many factors and the most important ones are Heparin Induced Thrombocytopenia (HIT) and anaphylaxis. However, Low Molecular Weight Heparin (LMWH) appears to be an effective and safe alternative treatment. Hence, it is preferred over than UH due to favorable pharmacokinetic and side effect profile. Direct Thrombin Inhibitors (DTI) is a promising class over the other anticoagulants since it offers potential advantages. The aim of this review is to discuss the differences between adult and pediatric thromboembolism and to review the current anticoagulants in terms of pharmacological action, doses, drug reactions, pharmacokinetics, interactions, and parameters. This review also highlights the differences between old and new anticoagulant therapy in pediatrics.

Pharmacokinetics and pharmacodynamics of anticoagulants in paediatric patients

Given the rising incidence of thrombotic complications in paediatric patients, understanding of the pharmacologic behaviour of anticoagulant drugs in children has gained importance. Significant developmental differences between children and adults in the haemostatic system and pharmacologic parameters for individual drugs highlight potentially unique aspects of anticoagulant pharmacology in this special and vulnerable population. This review focuses on pharmacologic information relevant to the dosing of unfractionated heparin, low molecular weight heparin, warfarin, bivalirudin, argatroban and fondaparinux in paediatric patients. The bulk of clinical experience with paediatric anticoagulation rests with the first three of these agents, each of which requires higher bodyweight-based dosing for the youngest patients, compared with adults, in order to achieve comparable pharmacodynamic effects, likely related to an inverse correlation between age and bodyweight-normalized clearance of these drugs. Whether extrapolation of therapeutic ranges targeted for adult patients prescribed these agents is valid for children, however, is unknown and a high priority for future research. Novel oral anticoagulants, such as dabigatran, rivaroxaban and apixaban, hold promise for future use in paediatrics but require further pharmacologic study in infants, children and adolescents.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.

Fluctuations of anti-Xa concentrations during maintenance enoxaparin therapy for neonatal thrombosis

AIM

To evaluate fluctuations in anti-Xa concentrations in infants treated with enoxaparin for thrombosis and describe clinical outcomes.

METHODS

A retrospective chart review was performed on infants treated with enoxaparin in the Neonatal Intensive Care Unit, and data on enoxaparin doses, anti-Xa concentrations, clinical characteristics and outcomes were abstracted.

RESULTS

Our cohort (n = 26) had a median gestation of 36 (range, 23-41) weeks, birthweight of 2522 (510-3912) grams and 5-min Apgar score of 8(4-9). Fifteen (57.7%) infants were males. Thromboses was diagnosed at a median age of 22 (range, 1-97) days; enoxaparin was initiated at 27.5 (range, 4-98) days at a mean (SD) dose of 1.4 (0.3) mg/kg every 12 h. Therapeutic anti-Xa concentrations (0.5-1 U/mL) were achieved at a mean (SD) dose of 2.1 (0.6) mg/kg at 12.5 (12.2) days of treatment. Of the 143 anti-Xa concentrations, 39 (27%) were within the therapeutic range. During maintenance therapy following initial therapeutic anti-Xa concentration, 40% concentrations were therapeutic. Minor bleeding was noted in four infants and intracranial bleed in one infant; four infants died. During treatment, thrombocytopenia, renal and hepatic impairment during treatment were noted in 7, 2 and 4 infants, respectively. Clot resolution was observed in 21 (81%) infants.

CONCLUSIONS

Anti-Xa concentrations fluctuate during maintenance enoxaparin therapy, with therapeutic levels being achieved only sporadically in young infants. Despite this, enoxaparin appears efficacious in thrombosis resolution. Further studies on the impact of stringent control of concentrations on outcomes in this population are warranted.

Safety of anticoagulants in children with arterial ischemic stroke

Pediatric arterial ischemic stroke (AIS) is increasingly diagnosed and carries significant risks of recurrence, morbidity, and mortality. Anticoagulant therapy (ACT) is commonly prescribed in childhood AIS. Hemorrhagic complication rates in pediatric stroke are unknown, and adult safety data are of limited applicability. We analyzed a prospectively enrolled cohort of children (aged 1 month-18 years) with acute AIS selected using standardized criteria for protocol-based ACT over14-year period. We assessed ACT-associated intracranial hemorrhage (ICH), including frequency, clinical and radiologic characteristics, predictors, and outcome. Among 215 children with AIS, 123 received ACT within 7 days after diagnosis. During anticoagulation, 14 (11%) children developed new or increased ICH, all within 26 days from diagnosis. ICH was symptomatic in 5 (4%), asymptomatic in 9 (7%), and mild (European Cooperative Acute Stroke Study grades HI1 or HI2) in all but 1 child (ECASS PH-2). Long-term neurologic outcomes after ACT-associated ICH in survivors were abnormal in 73% (8/11). Comparably, 12 of 75 (16%) children treated without anticoagulation developed new or increased ICH on follow-up imaging (P = .3507). We conclude that ACT is relatively safe in children with AIS, with a 4% risk of symptomatic ICH. Based on the safety of ACT in our study, clinical trials of ACT in childhood AIS are warranted.

FondaKIDS: a prospective pharmacokinetic and safety study of fondaparinux in children between 1 and 18 years of age

BACKGROUND

The incidence of thromboembolic disease is increasing in children. New anticoagulants have been licensed in adults and need to be studied in children. This report describes the first prospective study of fondaparinux in children.

PROCEDURE

The purpose of the study was to determine the dosing, pharmacokinetics, and safety of fondaparinux in children with deep vein thrombosis (DVT) or heparin-induced thrombocytopenia (HIT). Hospitalized children between 1 and 18 years of age with DVT or HIT received fondaparinux 0.1 mg/kg once daily. Fondaparinux-based anti-factor Xa levels were assessed at 2, 4, 12, and 24 hr following the first dose, and peak levels were measured twice weekly thereafter. Detailed pharmacokinetic analyses were performed.

RESULTS

Twenty four subjects in 3 age cohorts were enrolled and completed the study. Pharmacokinetic modeling demonstrated that a once-daily dose of fondaparinux at 0.1 mg/kg resulted in similar concentrations known to be efficacious in adults. Safety was demonstrated with only two bleeding events: one which may have pre-dated study drug administration and one which led only to temporary discontinuation of study drug.

CONCLUSION

Dosing of fondaparinux at 0.1 mg/kg once daily in children resulted in PK profiles comparable to those in adults receiving standard dosing. Fondaparinux can be considered an attractive alternative to LMWH given its once-daily dosing, acceptable safety data, and other favorable properties.

Preventing venous thrombosis in critically ill children: what is the right approach?

BACKGROUND

The incidence of venous thromboembolic (VTE) events in children has increased in recent years (J Neurosurg, 101, 2004, 32; J Thromb Haemost, 1, 2003, 1443) yet there is currently no consensus as to what VTE prophylaxis, if any, should be applied to the pediatric population.

OBJECTIVES/AIMS

Our aim was to audit current practice in pediatric VTE prophylaxis across England and Wales and to advocate simple measures for prevention. We illustrate the importance of the condition with a series of cases from the South West Paediatric Burns and Neurosurgical Services based in Bristol.

METHODS

Every pediatric intensive care unit (PICU) and burns center admitting children in England and Wales was invited to participate in a structured telephone questionnaire designed to find out how VTE in children were being prevented. We performed a literature review of specific risk factors and management of these factors.

RESULTS

Only one of the 24 units surveyed had written guidelines specific for children. Four other units used modified adult guidelines in older children. In the remaining 19 units that had no written guidelines, decisions regarding prophylaxis were based on individual cases and consultant-led.

CONCLUSION

There is no consensus in England and Wales as to which VTE prophylactic measures should be applied in patients <18 years of age. The National Institute for Health and Clinical Excellence (NICE) guidelines apply to adults only. Given the rarity of VTE events in children, it is unlikely that randomized controlled trials will provide the answer. We therefore propose that simple empirical measures be formally implemented in critically ill children to reduce the risk of developing this important but under-recognized condition.

Thrombotic disease in critically ill children

OBJECTIVES

To summarize a) epidemiology of arterial and venous thromboembolism, pulmonary embolism, and deep venous thrombosis in children; b) the risk factors for thrombosis in the pediatric intensive care unit; c) diagnostic techniques for arterial/venous thromboembolism; and d) the current recommendations for management and prevention of thromboembolic disease in critically ill children.

DATA SOURCE

Literature review, using National Library of Medicine PubMed and the following terms: arterial, venous thromboembolism; deep venous thrombosis; pulmonary embolism; thrombosis; as well as citations of interest from these articles.

STUDY SELECTION

Both pediatric and adult literature addressing thrombotic disease were reviewed.

DATA EXTRACTION AND SYNTHESIS

Articles were chosen for more extensive discussion when containing prospective studies, guidelines for practice, or data in critically ill patients. When data in children were unavailable, applicable data in adults were referenced. Due to the paucity of data in critically ill children, available adult and pediatric data were combined with institutional experience to provide suggestions for current practice and future inquiry.

CONCLUSIONS

Increasing awareness regarding the recognition and current approaches to management and prevention of thromboembolic disease in children is needed among pediatric intensivists, so outcome of these life-threatening processes might be improved.

Stability of Plasma Anti-Xa Activity in Low-Molecular-Weight Heparin Monitoring

Low-molecular-weight heparin (LMWH) is now the standard of care for prophylaxis and treatment of thromboembolic disorders. Only cases with renal failure, morbid obesity or extreme age require anti-Xa monitoring to assure the therapeutic level achievement. Because of infrequent requests, the test is usually sent to the reference laboratories and specimen handling may be delayed. Because LMWHs can be kept at ambient temperature for several days, we proposed that anti-Xa levels in plasma samples are similarly steady. Patients’ plasma that was requested for anti-Xa activity was left at room temperature to repeat the test 24 hours later and compare with the result of immediate assay. The study included 86 fresh specimens from 56 participants. All patients received enoxaparin with anti-Xa levels ranging from 0.1 to 2.5 U/mL. Notably, anti-Xa activities significantly rose on the second occasions (P = 8.4 × 10—10). The mean change of anti-Xa was +0.15 ± 0.21 U/mL (+24.9% ± 37.4%). Children (age <15 years) showed more marked alterations than adults (+40.9% vs. +18.2%, P = .008). There was no statistical difference in the degrees of changes between sexes and diagnoses. The data suggest that specimens sent for anti-Xa require prompt handling to prevent falsely elevated values. This observation is new and future research is needed to find the mechanism of this alteration.

Thrombosis in the critically ill neonate: incidence, diagnosis, and management

Among children, newborn infants are most vulnerable to development of thrombosis and serious thromboembolic complications. Amongst newborns, those neonates who are critically ill, both term and preterm, are at greatest risk for developing symptomatic thromboembolic disease. The most important risk factors are inflammation, DIC, impaired liver function, fluctuations in cardiac output, and congenital heart disease, as well as exogenous risk factors such as central venous or arterial catheters. In most clinically symptomatic infants, diagnosis is made by ultrasound, venography, or CT or MRI angiograms. However, clinically asymptomatic vessel thrombosis is sometimes picked up by screening investigations or during routine imaging for other indications. Acute management of thrombosis and thromboembolism comprises a variety of approaches, including simple observation, treatment with unfractionated or low molecular weight heparin, as well as more aggressive interventions such as thrombolytic therapy or catheter-directed revascularization. Long-term follow-up is dependent on the underlying diagnosis. In the majority of infants, stabilization of the patients’ general condition and hemodynamics, which allows removal of indwelling catheters, renders long-term anticoagulation superfluous. Nevertheless, in certain types of congenital heart disease or inherited thrombophilia, long-term prophylaxis may be warranted. This review article focuses on pathophysiology, diagnosis, and acute and long-term management of thrombosis in critically ill term and preterm neonates.