Venous thromboembolism in critically ill children

PICU Pharmacology

The care of the critically-ill child often includes medications used to optimize organ function, treat infections, and provide comfort. Pediatric pharmacology has some key differences that should be leveraged for safe pharmacologic management.

Secondary thrombosis prevention practice patterns in pediatrics: Results of an international survey

Background

Pediatric venous thromboembolism (VTE) rates continue to increase. Although most children present with transient provoking factors, some have persistent prothrombotic risks beyond the initial treatment period warranting secondary anticoagulation. Current pediatric VTE guidelines provide limited recommendations in this regard.

Objectives

Our primary objective was to identify key influences on pediatric thrombosis physicians' decisions to initiate secondary anticoagulation.

Methods

We targeted pediatric hematologists/oncologists internationally using Duration of Therapy for Thrombosis in Children, Children's Hospital Acquired Thrombosis consortium, and Venous Thromboembolism Network US pediatric subgroup membership rosters, who self-identified as primary outpatient thrombosis providers. Of 124 total surveys distributed, 61 complete surveys were evaluable. We defined secondary anticoagulation as anticoagulant use beyond the initial treatment period, on a daily basis (extended) or limited to periods of superimposed clinical risk factors (episodic).

Results

Pediatric thrombosis physicians surveyed indicated that they prescribe secondary anticoagulation in <25% of children despite persistent risks. Among those who indicated use of secondary anticoagulation, the preferred modality was extended anticoagulation in children with a history of recurrent unprovoked VTE (98%), chronic central venous catheter (74%), and potent thrombophilia (73%). Episodic anticoagulation was preferred in children with a history of mild thrombophilia (54%). Respondents were more likely to prescribe secondary anticoagulation for adolescents as opposed to children <12 years old.

Conclusions

Among pediatric thrombosis physicians surveyed, they perceived the prevalence of persistent prothrombotic risks to be high in children who have completed a course of anticoagulation for provoked VTE; however, estimated use of secondary anticoagulation was low. Studies involving real-world data are needed to further evaluate use of secondary anticoagulation in this setting.

Assessment of clinical characteristics and treatment outcomes of pediatric patients with intracardiac thrombosis: a single-center experience

The prevalence of intracardiac thrombus (ICT) is gradually increasing, though it is rare among children. Data related to the occurrence of ICT among children are limited, and treatment recommendations have been made utilizing adult guidelines. The primary objective of this study is to determine associated factors, management, and outcomes of intracardiac thrombosis in children. Between January 2013 and January 2020, patients diagnosed with ICT at the Pediatric Hematology-Oncology and Pediatric Cardiology departments in our hospital were included in the study. Demographic characteristics, clinical and laboratory findings, treatment protocols, and outcomes were analyzed retrospectively. The median age at diagnosis was 10.5 months (2 days to 14.5 years), and the median follow-up period was 6.5 months (1 month to 3.1 years). The most common primary diagnoses of the patients, in order of frequency, were heart disease (n: 8), metabolic disease (n: 3), prematurity and RDS (n: 3), burns (n: 2), pneumonia (n: 2), and asphyxia (n: 2). CVC was present in 19/23 of the patients. The reasons for CVC insertion were the need for plasmapheresis in one patient with a diagnosis of HUS and the need for well tolerated vascular access because of long-term hospitalization in others. LMWH was administered to all patients as first-line therapy. Complete response was achieved in 19 (79%) of 24 patients and 4 patients (16.6%) were unresponsive to medical treatment. It was found out that the thrombus location, type, sepsis, and hemoculture positivity, as well as the presence of CVC, had no impact on treatment response (chi-square P = 0.16, 0.12, 0.3, 0.49, 0.56). Moreover, no correlation was determined between thrombus size and treatment response (Mann Whitney U test P = 0.47). The mortality rate was determined to be 12.5% (3/24). Spontaneous occurrence of ICT is rare in childhood, without any underlying primary disease or associated factor. The presence of CVC, sepsis, and heart disease are factors associated with ICT. The success rate is increased with medical treatment. There was no significant difference in treatment response between the newborn and 1 month to 18-year-old patient group. It has been demonstrated that thrombus size, type, localization; sepsis, and hemoculture positivity had no impact on the treatment response.

Best Practice Recommendations for the Diagnosis and Management of Children With Pediatric Inflammatory Multisystem Syndrome Temporally Associated With SARS-CoV-2 (PIMS-TS; Multisystem Inflammatory Syndrome in Children, MIS-C) in Switzerland

Background: Following the spread of the coronavirus disease 2019 (COVID-19) pandemic a new disease entity emerged, defined as Pediatric Inflammatory Multisystem Syndrome temporally associated with COVID-19 (PIMS-TS), or Multisystem Inflammatory Syndrome in Children (MIS-C). In the absence of trials, evidence for treatment remains scarce. Purpose: To develop best practice recommendations for the diagnosis and treatment of children with PIMS-TS in Switzerland. It is acknowledged that the field is changing rapidly, and regular revisions in the coming months are pre-planned as evidence is increasing. Methods: Consensus guidelines for best practice were established by a multidisciplinary group of Swiss pediatric clinicians with expertise in intensive care, immunology/rheumatology, infectious diseases, hematology, and cardiology. Subsequent to literature review, four working groups established draft recommendations which were subsequently adapted in a modified Delphi process. Recommendations had to reach >80% agreement for acceptance. Results: The group achieved agreement on 26 recommendations, which specify diagnostic approaches and interventions across anti-inflammatory, anti-infectious, and support therapies, and follow-up for children with suspected PIMS-TS. A management algorithm was derived to guide treatment depending on the phenotype of presentation, categorized into PIMS-TS with (a) shock, (b) Kawasaki-disease like, and (c) undifferentiated inflammatory presentation. Conclusion: Available literature on PIMS-TS is limited to retrospective or prospective observational studies. Informed by these cohort studies and indirect evidence from other inflammatory conditions in children and adults, as well as guidelines from international health authorities, the Swiss PIMS-TS recommendations represent best practice guidelines based on currently available knowledge to standardize treatment of children with suspected PIMS-TS. Given the absence of high-grade evidence, regular updates of the recommendations will be warranted, and participation of patients in trials should be encouraged.

Venous Thromboembolism among Noncritically Ill Hospitalized Children: Key Considerations for the Pediatric Hospital Medicine Specialist

Venous thromboembolism (VTE) is a leading cause of morbidity and preventable harm among noncritically ill hospitalized children. Several clinical factors relevant to the noncritically ill hospitalized child significantly increase the risk of VTE including the presence of central venous catheters, systemic inflammation, and prolonged immobilization. Although risk mitigation strategies have been described, the diagnosis, treatment, and prevention of VTE require standardization of institutional practices combined with multidisciplinary collaboration among pediatric hospitalists, hematologists, and other care providers. In this narrative review, we summarize the epidemiology of VTE, risk models identifying high-risk conditions associated with VTE, and prevention and treatment strategies. We further describe successful quality improvement efforts implementing institutional VTE risk stratification and thromboprophylaxis procedures. Finally, we highlight unique challenges facing pediatric hospital medicine specialists in the era of the COVID-19 pandemic, including caring for adults admitted to pediatric hospital units, and describe future research opportunities for VTE in the noncritically ill hospitalized child.

Pediatric Fibrinogen PART II-Overview of Indications for Fibrinogen Use in Critically Ill Children

Bleeding is frequently seen in critically ill children and is associated with increased morbidity and mortality. Fibrinogen is an essential coagulation factor for hemostasis and hypofibrinogenemia is an important risk factor for bleeding in pediatric and adult settings. Cryoprecipitate and fibrinogen concentrate are often given to critically ill children to prevent bleeding and improve fibrinogen levels, especially in the setting of surgery, trauma, leukemia, disseminated intravascular coagulopathy, and liver failure. The theoretical benefit of fibrinogen supplementation to treat hypofibrinogenemia appears obvious, yet the evidence to support fibrinogen supplementation in children is sparce and clinical indications are poorly defined. In addition, it is unknown what the optimal fibrinogen replacement product is in children and neonates or what the targets of treatment should be. As a result, there is considerable variability in practice. In this article we will review the current pediatric and applicable adult literature with regard to the use of fibrinogen replacement in different pediatric critical care contexts. We will discuss the clinical indications for fibrinogen supplementation in critically ill children and the evidence to support their use. We summarize by highlighting current knowledge gaps and areas for future research.

The survival benefit of low molecular weight heparin over unfractionated heparin in pediatric trauma patients

INTRODUCTION

Venous thromboembolism (VTE) prophylaxis in pediatric patients is controversial and is mainly dependent on protocols derived from adult practices. Our study aimed to compare outcomes among pediatric trauma patients who received low molecular weight heparin (LMWH) compared to those who received unfractionated heparin (UFH).

METHODS

We performed 2 years (2015-2016) retrospective analysis of the Pediatrics ACS-TQIP database. Pediatric trauma patients (age ≤17) who received thromboprophylaxis with either LMWH or UFH were included. Patients were stratified into three age groups. Analysis of each subgroup and the entire cohort was performed. Outcome measures included VTE events (deep vein thrombosis [DVT] and pulmonary embolism [PE]), hospital and ICU length of stay (LOS) among survivors, and mortality. Propensity score matching was used to match the two cohorts LMWH vs UFH.

RESULTS

A matched cohort of 1,678 pediatric trauma patients was analyzed. A significant difference in survival, DVT events, and in-hospital LOS was seen in the age groups above 9 years. Overall, the patients who received LMWH had lower mortality (1.4% vs 3.6%, p<0.01), DVT (1.7% vs 3.7%, p<0.01), and hospital LOS among survivors (7 days vs 9 days, p<0.01) compared to those who received UFH. There was no significant difference in the ICU LOS among survivors and the incidence of PE between the two groups.

CONCLUSION

LMWH is associated with increased survival, lower rates of DVT, and decreased hospital LOS compared to UFH among pediatric trauma patients age 10-17 years.

LEVEL OF EVIDENCE

Level III Prophylactic.

STUDY TYPE

Prophylactic.

Evaluating the Impact of Central Venous Catheter Materials and Design on Thrombosis: A Systematic Review and Meta-Analysis

BACKGROUND

Thrombosis is a common complication associated with central venous catheter (CVC) insertion. Several antithrombogenic materials and alterations to catheter design have been developed to lower thrombosis rates.

AIM

To systematically evaluate the effectiveness and safety of antithrombogenic materials and alterations to CVC design on thrombosis rates.

METHODS

A systematic search was completed of main databases (CINAHL, EMBASE, MEDLINE, and PubMed) as well as trial registries and gray literature. Randomized controlled trials conducted in any age group, published in English language since 2008 reporting impact of different CVC designs or materials on thrombosis were included, to capture studies that reflect contemporary products and practice. Cochrane systematic review methodology was followed, including independent study selection and data extraction. Quality appraisal was conducted using the Cochrane risk of bias tool. A narrative synthesis and meta-analysis in RevMan were conducted.

RESULTS

From a possible 232 studies, nine studies met the inclusion criteria. Four studies (n = 1,320) assessed different catheter materials; four studies (n = 591) compared different CVC designs, and one study (n = 150) evaluated impact of combined design and material on outcomes. Meta-analysis demonstrated that neither catheter material nor design alone or in combination had a significant impact on thrombosis (RR: 0.98 [95% CI 0.87, 1.11]). Different catheter materials and design also had no significant impact on occlusion or CRBSI. Studies were of mixed quality overall.

LINKING EVIDENCE TO ACTION

Different CVC materials and designs were not associated with a reduction in the risk of either catheter-related thrombosis or infection. Overall reporting and small sample sizes make it difficult to draw firm conclusions. Larger, quality randomized trials are required to provide evidence about the possible merits of innovative catheter design and materials on patient outcomes.

Safety of dabigatran etexilate for the secondary prevention of venous thromboembolism in children

This open-label, single-arm, prospective cohort trial is the first phase 3 safety study to describe outcomes in children treated with dabigatran etexilate for secondary venous thromboembolism (VTE) prevention. Eligible children aged 12 to <18 years (age stratum 1), 2 to <12 years (stratum 2), and >3 months to <2 years (stratum 3) had an objectively confirmed diagnosis of VTE treated with standard of care (SOC) for ≥3 months, or had completed dabigatran or SOC treatment in the DIVERSITY trial (NCT01895777) and had an unresolved clinical thrombosis risk factor requiring further anticoagulation. Children received dabigatran for up to 12 months, or less if the identified VTE clinical risk factor resolved. Primary end points included VTE recurrence, bleeding events, and mortality at 6 and 12 months. Overall, 203 children received dabigatran, with median exposure being 36.3 weeks (range, 0-57 weeks); 171 of 203 (84.2%) and 32 of 203 (15.8%) took capsules and pellets, respectively. Overall, 2 of 203 children (1.0%) experienced on-treatment VTE recurrence, and 3 of 203 (1.5%) experienced major bleeding events, with 2 (1.0%) reporting clinically relevant nonmajor bleeding events, and 37 (18.2%) minor bleeding events. There were no on-treatment deaths. On-treatment postthrombotic syndrome was reported for 2 of 162 children (1.2%) who had deep vein thrombosis or central-line thrombosis as their most recent VTE. Pharmacokinetic/pharmacodynamic relationships of dabigatran were similar to those in adult VTE patients. In summary, dabigatran showed a favorable safety profile for secondary VTE prevention in children aged from >3 months to <18 years with persistent VTE risk factor(s). This trial was registered at www.clinicaltrials.gov as #NCT02197416.

Venous Thromboembolism in Children: From Diagnosis to Management

Venous thromboembolism (VTE) in children is a rare occurrence, although in recent decades we have seen an increase due to several factors, such as the rise in survival of subjects with chronic conditions, the use of catheters, and the increased sensitivity of diagnostic tools. Besides inherited thrombophilia, acquired conditions such as cardiovascular diseases, infections, chronic disorders, obesity and malignancy are also common risk factors for paediatric VTE. The treatment of paediatric VTE consists of the use of heparins and/or vitamin K antagonists to prevent dissemination, embolization, and secondary VTE. Randomized clinical trials of direct oral anticoagulants in paediatric VTE are ongoing, with the aim to improve the compliance and the care of patients. We reviewed the physiological and pathological mechanisms underlying paediatric thrombosis and updated the current diagnosis and treatment options.

Management of thrombosis in children and neonates: practical use of anticoagulants in children

Venous thrombosis (VTE) in children and neonates presents numerous management challenges. Although increasing in frequency, VTE in children and neonates is still uncommon compared with adults. The epidemiology of VTE is vastly different in neonates vs children vs adolescents vs adults. In reality, pediatric thrombosis should be viewed as a multitude of rare diseases (eg, renal vein thrombosis, spontaneous thrombosis, catheter-related thrombosis, cerebral sinovenous thrombosis), all requiring different approaches to diagnosis and with different short- and long-term consequences, but linked by the use of common therapeutic agents. Further, children have fundamentally different physiology in terms of blood flow, developmental hemostasis, and, likely, endothelial function. The American Society of Hematology 2017 Guidelines for Management of Venous Thromboembolism: Treatment of Pediatric VTE provides up-to-date evidence-based guidelines related to treatment. Therefore, this article will focus on the practical use of therapeutic agents in the management of pediatric VTE, especially unfractionated heparin, low-molecular-weight heparin, and oral vitamin K antagonists, as the most common anticoagulants used in children. Direct oral anticoagulants (DOACs) remain in clinical trials in children and should not be used outside of formal trials for the foreseeable future.

American Society of Hematology 2018 Guidelines for management of venous thromboembolism: treatment of pediatric venous thromboembolism

BACKGROUND

Despite an increasing incidence of venous thromboembolism (VTE) in pediatric patients in tertiary care settings, relatively few pediatric physicians have experience with antithrombotic interventions.

OBJECTIVE

These guidelines of the American Society of Hematology (ASH), based on the best available evidence, are intended to support patients, clinicians, and other health care professionals in their decisions about management of pediatric VTE.

METHODS

ASH formed a multidisciplinary guideline panel that included 2 patient representatives and was balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including updating or performing systematic evidence reviews (up to April of 2017). The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 30 recommendations, covering symptomatic and asymptomatic deep vein thrombosis, with specific focus on management of central venous access device-associated VTE. The panel also addressed renal and portal vein thrombosis, cerebral sino venous thrombosis, and homozygous protein C deficiency.

CONCLUSIONS

Although the panel offered many recommendations, additional research is required. Priorities include understanding the natural history of asymptomatic thrombosis, determining subgroup boundaries that enable risk stratification of children for escalation of treatment, and appropriate study of newer anticoagulant agents in children.

Central Venous Catheter-associated Venous Thromboembolism in Children With Hematologic Malignancy

In pediatric oncology, the diagnosis of a hematologic malignancy and presence of a central venous catheter (CVC) have been identified as significant risk factors for the development of a venous thromboembolism (VTE). There remain little data regarding CVC factors associated with CVC-related VTE. Using the VTE and oncology database in a quaternary care center, a retrospective cohort study was conducted in children below 18 years old with hematologic cancer from November 5, 2012 to April 4, 2016. Patient, CVC factors, and VTE occurrence were analyzed to identify significant patient and CVC factors associated with the development of clinically identified CVC-related VTE. Utilizing the χ, Mann-Whitney, and the Fisher exact tests, patient factors were compared across VTE yes/no groups. Of the 198 study patients, 22 VTE cases were identified. Eighteen VTE events were CVC-associated, occurring in 9% of study population. Peripherally inserted central catheter lines and older ages were associated with VTE. The use of tissue-plasminogen activator for CVC occlusion was associated with decreased VTE rates, suggesting a protective potential.

Thrombolysis Using Tissue Plasminogen Activator: Experience from a Critical Care Setting

To describe the experience of thrombolysis using tissue plasminogen activator (tPA) in critically ill children admitted to the pediatric intensive care unit (PICU), retrospective review of medical records of all children (1 month-16 years), who were admitted in PICU since January 2014 to December 2017 and received systemic tPA for thrombolysis was done. Data was collected on a structured proforma and included thrombus location, tPA dose and duration, outcome (resolution, survival) and complications (bleeding). Total 9 patients (7 males, 2 females) received systemic tPA therapy for thrombolysis with mean age of 74.64 ± 69.58 months. Two patients had thrombus in femoral artery, 3 in IVC and 4 had intra-cardiac thrombosis. Median number of doses was 2 with a range of 1-5 doses. Complete resolution of the clot was noted in all except one patient. A standard starting dose of 0.01 mg/kg/h was used in all patients. Only one patient developed melena after TPA therapy which self-resolved. Systemic tPA therapy was very safe in pediatric critically ill patients and was effective for thrombolysis and did not show any adverse effects in children with varying underlying diagnosis.

The Impact of Central Venous Catheters on Pediatric Venous Thromboembolism

The use of central venous catheters (CVCs) in children is escalating, which is likely linked to the increased incidence of pediatric venous thromboembolism (VTE). In order to better understand the specific risk factors associated with CVC-VTE in children, as well as available prevention methods, a literature review was performed. The overall incidence of CVC-VTE was found to range from 0 to 74%, depending on the patient population, CVC type, imaging modality, and study design. Throughout the available literature, there was not a consistent determination regarding whether a particular type of central line (tunneled vs. non-tunneled vs. peripherally inserted vs. implanted), catheter material, insertion technique, or insertion location lead to an increased VTE risk. The patient populations who were found to be most at risk for CVC-VTE were those with cancer, congenital heart disease, gastrointestinal failure, systemic infection, intensive care unit admission, or involved in a trauma. Both mechanical and pharmacological prophylactic techniques have been shown to be successful in preventing VTE in adult patients, but studies in children have yet to be performed or are underpowered. In order to better determine true CVC-VTE risk factors and best preventative techniques, an increase in large, prospective pediatric trials needs to be performed.

Screening Guidelines for Venous Thromboembolism Risk in Hospitalized Children Have Low Sensitivity for Central Venous Catheter-Associated Thrombosis

OBJECTIVES

Local pediatric screening guidelines for venous thromboembolism (VTE) are developed from incomplete pediatric data and extrapolated from adult data in which immobility is a major risk factor. We hypothesized that screening guidelines centered on immobility are inadequate for identifying children at risk of central venous catheter (CVC)-associated VTE.

METHODS

This retrospective case-control (4:1) study at an academic, quaternary-level, free-standing children's hospital applied screening guidelines for VTE risk to all cases of VTE from July 2012 to April 2014. Cases and controls were classified as "at risk" or "not at risk" of VTE by guideline criteria. These guidelines assessed VTE risk factors, including CVC, as reported in the pediatric literature.

RESULTS

VTE prevalence was 0.5 per 100 admissions. Sixty-nine of 114 patients with radiographically confirmed VTE were classified as being "at risk" by the guidelines, with a sensitivity of 61%, specificity of 90.8%, a positive predictive value of 2.4%, and negative predictive value of 99.8%. There was no difference in screening guidelines sensitivity for identifying CVC-associated VTE versus non-CVC-associated VTE. Half of the 45 patients with VTE who were not captured as being "at risk" did not have decreased mobility, the entry point to the algorithm, and 80% of these patients had a CVC.

CONCLUSIONS

Screening guidelines have low sensitivity for identifying hospitalized children at increased risk of both CVC-associated and other VTE events. Decreased mobility is not a requirement for CVC-associated VTE. Risk factors extrapolated from adult data are insufficient for identifying children at risk of VTE.

Deep Venous Thrombosis in Teen With Crouzon Syndrome Post-Le Fort III Osteotomy With Rigid External Distraction

Venous thromboembolic events are rare in pediatric patients. Risk factors associated with the development of venous thromboembolic events in pediatric patients include the use of central venous catheters, hospitalization, cancer, sepsis, trauma, surgery, and congenital prothrombotic disorders.The authors present the case of a 14-year-old man with Crouzon syndrome who required Le Fort III osteotomy with rigid external distraction for significant midface hypoplasia who presented postoperatively with an extensive deep venous thrombosis. This is the first reported case of symptomatic venous thrombosis post-Le Fort III osteotomy and rigid external distraction. Although rare, surgeons should be aware of this potential complication.

Risk of venous thromboembolism in children after general surgery

BACKGROUND/PURPOSE

The purpose of the study was to determine absolute and relative rates of venous thromboembolism (VTE) following general surgical procedures in children compared to the general population.

METHODS

We analyzed data from all patients under the age of 18years in the Clinical Practice Research Datalink, linked to Hospital Episode Statistics from England (2001-2011) undergoing a general surgical procedure and population controls. Crude rates of VTE and adjusted hazard ratios were calculated using Cox regression.

RESULTS

We identified 15,637 children who had a surgical procedure with 161,594 controls. Six children undergoing surgery had a VTE diagnosed in the year after compared to five children in the population cohort. The overall rate of VTE following surgery was 0.4 per 1000 person years (pyrs) (95% confidence interval [CI] 0.15-0.88) compared to 0.04 per 1000 pyrs (95% CI 0.02-0.09) in the population cohort. This represented a 9 fold increase in risk compared to the population cohort (adjusted hazard ratio [HR] 8.80; 95% CI 2.59-29.94).

CONCLUSIONS

Children are at increased risk for VTE following general surgical procedures compared to the general population however the absolute risk is small and given this the benefits of thromboprophylaxis need to be balanced against the risk of complications following its use.