IV Versus Subcutaneous Enoxaparin in Critically Ill Infants and Children: Comparison of Dosing, Anticoagulation Quality, Efficacy, and Safety Outcomes

Questions around a case of in utero thrombosis in a premature child, concerning the management of anticoagulant treatments

We report the case of a preterm infant presenting a thrombosis, discovered on ultrasound at 22 weeks of gestational age and confirmed at birth following additional examinations. We describe the anticoagulant treatment of this patient by intravenous enoxaparin, tinzaparin and rivaroxaban, from questioning to practice.

Pharmacokinetic model-guided enoxaparin dosing in the Neonatal ICU: Retrospective cohort study to plan for prospective feasibility trial

Traditional milligram per kilogram (mg/kg) dosing of enoxaparin in neonates frequently fails to achieve target anti-Xa levels promptly, necessitating repeated laboratory monitoring and dose adjustments. This study investigated whether a personalized dosing strategy based on predicted individual clearance and volume of distribution could improve outcomes, comparing standard-of-care (SOC) mg/kg dosing to pharmacokinetic (PK) model-informed precision dosing (MIPD). A retrospective analysis was conducted on hospitalized neonates treated with enoxaparin at less than 44 weeks postmenstrual age from 2019 to 2022. Data on demographics, drug dosing, PK model covariates, and clinical outcomes were extracted from electronic health records and analyzed using the Pumas-AI Lyv dosing tool. The primary focus was on comparing the initial SOC dose to the MIPD-recommended dose. The secondary outcome measured was the time required to achieve therapeutic anti-Xa levels. The study included 168 neonates with a median postnatal age of 15 days (range 1-149) and a median dosing weight of 3.1 kg (range: 0.82-5.2). MIPD-recommended initial doses were 20%-60% higher than SOC doses in 32% of the cases and over 60% higher in 11% of cases. Neonates who received SOC doses that were much lower than the MIPD recommendation showed the longest delays in reaching therapeutic anti-Xa levels. The results indicate that PK model-informed of enoxaparin dosing leads to higher initial dosages than SOC in neonates, potentially reducing the time to therapeutic anti-Xa levels. These findings are being utilized to define dosing limits for a prospective trial of MIPD in neonatal intensive care settings.

Clinical Impact of a Standardized Risk-Stratified Thromboprophylaxis Protocol for Multisystem Inflammatory Syndrome in Children

OBJECTIVE

To evaluate the clinical impact of an institutional thromboprophylaxis protocol in patients with multisystem inflammatory syndrome in children (MIS-C), who are at increased risk for thromboembolism (TE).

STUDY DESIGN

We conducted a single-center retrospective cohort study of children less than 18 years between March 2020 and December 2021. Eligible patients were confirmed with MIS-C and were managed with a standardized multidisciplinary treatment approach that included a thromboprophylaxis protocol to guide and unify clinical practice. For high-risk patients, prophylactic dose enoxaparin (target anti-Factor Xa 0.1-0.3 U/mL) was added. In high-risk patients with TE risk factors persistent at hospital discharge, thromboprophylaxis was prescribed for an additional 30 days.

RESULTS

Of 135 patients with MIS-C, 124 (92%) required intensive care unit stay and 64 (47%) required a central venous catheter for a median duration of 5 days (IQR, 4-7). Prophylactic dose enoxaparin was initiated in 116 out of 121 patients (96%) deemed high-risk per our protocol at a median of 1 day after admission [IQR, 0-3] achieving target levels at a median of 1 day [IQR, 1-2]. The median initial anti-Factor Xa level was 0.13 u/mL [IQR, 0.05-0.19]. One patient (0.7%) developed symptomatic noncatheter related superficial vein thrombosis requiring therapeutic anticoagulation. Thromboprophylaxis was extended for 30 days after discharge in 108 out of 135 patients (80%). Bleeding events occurred in 5 patients during hospitalization (4.2%). All bleeding events were clinically relevant nonmajor bleeding. There were no deaths.

CONCLUSIONS

Implementation of an institutional standardized thromboprophylaxis protocol in MIS-C was feasible and led to timely initiation of prophylactic anticoagulation and low rates of TEs and bleeding complications.

Retrospective Evaluation of Intravenous Enoxaparin Administration in Feline Arterial Thromboembolism

Simple Summary

Feline arterial thromboembolism is a painful disease characterized by acute ischemic necrosis of one or more limbs due to cardiac diseases, hyperthyroidism, or neoplasia. Among others, medical treatment consists of preventing new thrombus formation primarily using heparin products, such as enoxaparin. This retrospective study reports clinical data, regain of perfusion, short-term outcome, and complications of 36 affected cats treated with a novel intravenous enoxaparin protocol. Furthermore, we aimed to report monitoring and management of the intravenous enoxaparin treatment for this disease. In our population, visible hemorrhage was rare. The most common causes of death/euthanasia were cardiac instability, acute kidney injury, neurological abnormalities, and limb necrosis. The hospital discharge rate was 47% overall and was significantly different between single limb (83%) and dual limb (29%) thromboembolism. Our study supports the intravenous use of enoxaparin in combination with oral clopidogrel for cats with thromboembolism as an alternative treatment method.

Abstract

Induction of a hypocoagulable state is imperative in the treatment of feline arterial thromboembolism. Publications in human medicine report the use of enoxaparin intravenously in selected cases. The aim of our retrospective study was to report the regain of perfusion, short-term outcome, and complications of cats treated with a novel intravenous enoxaparin protocol (1 mg/kg bolus injection followed by 3 mg/kg/day continuous infusion) combined with oral clopidogrel administration. The secondary aim was to report the monitoring of enoxaparin with anti-Xa activity. There were 36 cats included. The probability of reaching limb reperfusion was significantly (p = 0.0148) higher with anti-Xa activity within or above the target range compared to results below the target range (19/21, 90% versus 11/20, 55%). The complications observed were acute kidney injury (15/36, 42%), hemorrhage (2/36, 6%), and neurological signs (6/36, 17%). The most common causes of death/euthanasia were cardiac instability, acute kidney injury, neurological abnormalities, and limb necrosis. The hospital discharge rate was 83% (10/12) for single limb and 29% (7/24) for dual limb thrombosis; the difference was significant (p = 0.0039). The median hospitalization time for the survivors was 119.5 (95–480) h. Our study supports the use of intravenous continuous rate infusion of enoxaparin in combination with oral clopidogrel for cats with aortic thromboembolism. We report similar discharge rates and lower hemorrhage rates than previously reported with thrombolytic treatment.

How to use low-molecular-weight heparin to treat neonatal thrombosis in clinical practice

Among children, neonates have the highest incidence of thrombosis due to risk factors such as catheter instrumentation, an evolving coagulation system and congenital heart disease. Low-molecular-weight heparins (LMWHs) are the most commonly used anticoagulants in neonates. Published guidelines delineate dosing and monitoring protocols for LMWH therapy in newborns. However, challenging clinical situations frequently present that warrant healthcare providers to think critically beyond the range of guidelines, and judiciously resolve specific problems. This review describes the use of LMWH in the neonatal population, including practical aspects such as route and site of administration, preparation from concentrated formulations and methods to minimize pain of subcutaneous injection. It is followed by a discussion on dosing, monitoring and outcomes of LMWH therapy in neonates. The risk of recurrence of thrombosis in neonates after LMWH therapy is approximately 3% based on a pooled analysis of studies reporting this outcome over the last 24 years. The article concludes with an overview of the side-effects of LMWH, including the risk of bleeding which is around 4% based on pooled analyses of more than 30 studies.

The Trilogy of SARS-CoV-2 in Pediatrics (Part 3): Thrombosis, Anticoagulant, and Antiplatelet Considerations

The hypercoagulable state induced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects all patients regardless of age. The incidence of venous thromboembolism in pediatric patients with SARS-CoV-2-related illnesses is not well established. Although deep vein thrombosis is rare in children in the absence of risk factors, coagulopathy and the development of thromboses have been described in pediatric patients with acute COVID-19 and multisystem inflammatory syndrome. This comprehensive review provides a detailed overview of SARS-CoV-2-associated coagulopathy as well as strategies for optimizing the evaluation, management, and prevention of thrombosis in pediatric patients.

Diagnosis and Management of Pediatric Venous Thromboembolism: New Therapies on the Horizon

ABSTRACT

The incidence of venous thromboembolism (VTE) is increasing in pediatric patients. Prompt recognition and evaluation of VTE in young patients could prevent significant morbidity or mortality. In contrast to VTE in adults, current treatment guidelines are largely based on expert opinion as limited randomized controlled trial data exist about the appropriate management in pediatric patients with traditional anticoagulants. However, recently approved direct-acting oral anticoagulants in adults are also being investigated in pediatric VTE and these data could inform future evidence-based treatment principles. Thus, healthcare providers must be well informed about the management of pediatric VTE and the data from these trials to date. This continuing medical education article will provide a summary of management of pediatric VTE with particular emphasis on emerging direct-acting oral anticoagulants.

Anti-Xa levels in critically ill children receiving enoxaparin for venothromboembolism prophylaxis

Venothrombolism (VTE) prophylaxis is increasingly utilized in pediatric intensive care units (PICUs). Enoxaparin, a low-molecular weight heparin, is frequently used for this purpose. Enoxaparin can also be used for therapeutic anticoagulation in cases of known thrombus. In such cases, monitoring involves obtaining serum anti- Xa levels with a target value of 0.5-1 units/mL. No monitoring recommendations currently exist for enoxaparin when intended for pediatric VTE prophylaxis. We hypothesize that a clinically important number of patients on VTE prophylaxis with enoxaparin have serum anti-Xa levels consistent with values targeted for therapeutic anticoagulation. We found that over 20% of patients on VTE prophylaxis with enoxaparin had serum anti-Xa levels consistent with true therapeutic anticoagulation (anti-Xa level 0.5-1 units/mL) during their enoxaparin course and 5% achieved values of supratherapeutic anticoagulation (anti-Xa level >1 units/mL). Serum anti-Xa level did not correlate with once versus twice daily dosing, body mass index (BMI), or creatinine level. Blood urea nitrogen (BUN) was found to have a positive odds ratio for an anti-Xa level ≥ 0.5 units/mL. We believe that this incidence of unintended therapeutic anticoagulation indicates a clinically significant number and therefore routine anti-Xa evaluation while on VTE prophylaxis is warranted within our population.

Low-Molecular-Weight Heparin and Fondaparinux Use in Pediatric Patients With Obesity

OBJECTIVE

The objective of this study is to comprehensively review the efficacy and safety data of low-molecular-weight heparins (LMWHs) and fondaparinux in pediatric patients with obesity.

DATA SOURCES

A comprehensive literature search of PubMed, SCOPUS, CINAHL, Academic Search Complete, PsycInfo, Cochrane Library, and Web of Science databases was conducted (1900 to July 2020). Search terms utilized included LMWH, low-molecular-weight heparin, enoxaparin, dalteparin, tinzaparin, fondaparinux, pediatric, child, children, obese, obesity, overweight. No limits or timeline restrictions were imposed.

STUDY SELECTION AND DATA EXTRACTION

Studies that reported pediatric patients with described overweight or obesity and utilized LMWHs or fondaparinux were considered.

DATA SYNTHESIS

Of 207 studies screened, 12 were included. Average dose reductions of 12.9% to 37.3% from the starting dose were observed with treatment indications of enoxaparin and increased up to 27.3% for prophylactic indications. Trends could not be concluded in the dalteparin and fondaparinux studies. Four thrombotic and 15 bleeding events were reported in the studies.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Pediatric patients with obesity may initially be underdosed or overdosed with enoxaparin compared with children with healthy body weight, depending on the indication.

CONCLUSION

Pediatric patients with obesity may benefit from proactively adjusting enoxaparin dosing on initiation of therapy. Further studies are needed for dalteparin and fondaparinux in these populations. Clinical controversy exists with the relevance of monitoring these high-risk medications for therapeutic and prophylactic indications. Thrombotic and hemorrhagic events were similar to reported adult outcomes.

Intravenous Enoxaparin in Pediatric Burn Patients: A Case Series

Patients with acute burns experience a hypercoagulable state that may necessitate the use of anticoagulants to prevent the complications of venous thromboembolism (VTE). Enoxaparin is a low molecular weight heparin that is commonly used for this purpose; however, the traditional SC route of administration poses potential limitations in the pediatric burn population. These include pain upon injection, increased anxiety, erroneous absorption and distribution, and difficulty in finding an administration site when burns encompass a large percentage of body surface area. As a result, the IV route of administration may be preferable in these patients. To date, a limited number of studies in critically ill pediatric patients have been performed. In this report, we present a case series of 3 pediatric burn patients who initially received SC enoxaparin and were transitioned to IV enoxaparin for VTE prophylaxis. The patients were 2, 8, and 10 years old. Burn involvement ranged from 8% to 75% total body surface area, and all patients had central line access. Adequate prophylactic low molecular weight heparin anti-Xa peak concentrations (0.1-0.3 international units/mL) were achieved with IV doses ranging from 0.35 to 0.5 mg/kg administered every 12 hours. No adverse effects, major bleeding events, or treatment failures occurred.

Establishment of prophylactic enoxaparin dosing recommendations to achieve targeted anti-factor Xa concentrations in children with CHD

BACKGROUND

Enoxaparin may be used to prevent central venous catheter-related thrombosis in patients with CHD. We aimed to determine whether current enoxaparin dosing regimens effectively achieve anti-factor Xa concentrations within prophylactic goal ranges in this patient population.

METHODS

We implemented a formal protocol aimed at reducing central venous catheter-related thrombosis in children with CHD in January, 2016. Standard empiric prophylactic enoxaparin dosing regimens were used - for example, 0.75 mg/kg/dose every 12 hours for patients <2 months of age and 0.5 mg/kg/dose every 12 hours for patients ⩾2 months of age - with anti-factor Xa goal range of 0.25-0.49 IU/ml. Patients <2 years of age who received enoxaparin and had at least one valid steady-state anti-factor Xa measurement between 25 January, 2016 and 31 August, 2016 were retrospectively reviewed.

RESULTS

During the study period, 47 patients had 186 anti-factor Xa concentrations measured, of which 20 (11%) were above and 112 (60%) were below the prophylactic goal range. Anti-factor Xa concentrations within the goal range were ultimately achieved in 31 patients. Median dose required to achieve anti-factor Xa concentrations within the prophylactic range was 0.89 mg/kg/dose (25, 75%: 0.75, 1.11) for patients <2 months (n=23 patients) and 0.79 mg/kg/dose (25, 75%: 0.62, 1.11) for patients ⩾2 months (n=8 patients).

CONCLUSIONS

Enoxaparin doses required to achieve prophylactic anti-factor Xa concentrations in young children with CHD were consistently higher than the currently recommended prophylactic dosing regimens. Further study is needed to determine whether dose titration to achieve prophylactic anti-factor Xa concentrations is effective in preventing central venous catheter-related thrombosis.

Anticoagulant prophylaxis and therapy in children: current challenges and emerging issues

This review is aimed at describing the unique challenges of anticoagulant prophylaxis and treatment in children, and highlighting areas for research for improving clinical outcomes of children with thromboembolic disease. The evidence presented demonstrates the challenges of advancing the evidence base informing optimal management of thromboembolic disease in children. Recent observational studies have identified risk factors for venous thromboembolism in children, but there are few interventional studies assessing the benefit-risk balance of using thromboprophylaxis in risk-stratified clinical subgroups. A risk level-based framework is proposed for administering mechanical and pharmacological thromboprophylaxis. More research is required to refine the assignment of risk levels. The anticoagulants currently used predominantly in children are unfractionated heparin, low molecular weight heparin, and vitamin K antagonists. There is a paucity of robust evidence on the age-specific pharmacology of these agents, and their efficacy and safety for prevention and treatment of thrombosis in children. The available literature is heterogeneous, reflecting age-specific differences, and the various clinical settings for anticoagulation in children. Monitoring assays and target ranges are not well established. Nevertheless, weight-based dosing appears to achieve acceptable outcomes in most indications. Given the limitations of the classical anticoagulants for children, there is great interest in the direct oral anticoagulants (DOACs), whose properties appear to be particularly suitable for children. All DOACs currently approved for adults have Pediatric Investigation Plans ongoing or planned. These are generating age-specific formulations and systematic dosing information. The ongoing pediatric studies still have to establish whether DOACs have a positive benefit-risk balance in the various pediatric indications and age groups.