Thrombosis risk factor assessment and implications for prevention in critically ill children

Thromboembolism in Children

OBJECTIVE

To study pediatric patients who were diagnosed with thrombosis between January 2009 and March 2020.

METHODS

Patients were evaluated with respect to thrombophilic risk factors, localization of the thrombus, response to treatment, and recurrence rates during the last 11 y.

RESULTS

Among 84 patients, 59 (70%) had venous thrombosis and 20 (24%) had arterial thrombosis. The number of documented thrombosis amongst hospitalized children in authors' hospital has increased over the years. It has been observed that the annual incidence of thromboembolism has increased after 2014. Thirteen patients were recorded between 2009 and 2014 and 71 patients between 2015 and 2020 (until March 2020). Exact thrombosis localization could not be detected in 5 patients. The median age of patients was 8 ± 5.95 (range 0-18). Fourteen children (16.9%) had a history of familial thrombosis. Genetic and/or acquired risk factors were detected in 81 (96.4%) of the patients. Overall, 64 patients (76.1%) had acquired risk factors such as infection (20.2%), catheterization (13.1%), liver disease (11.9%), mastoiditis (8.3%), liver transplantation (6%), hypoxic-ischemic encephalopathy (4.8%), dehydration (3.6%), trauma (3.6%) and cancer (2.4%). As genetic risk factors, the most common genetic mutations were PAI-1 4G>5G, MTHFR C677T, and MTHFR A1298C mutations. Twenty-eight (41.2%) patients had at least one genetic thrombophilic mutation. At least one homozygous mutation in 37 patients (44%) and at least one heterozygous mutation in 55 patients (65.4%) were detected.

CONCLUSIONS

The annual incidence of thrombosis has increased over the years. Genetic predisposition and acquired risk factors play an important role in etiology, treatment, and follow-up in children with thromboembolism. Especially, genetic predisposition is common. Thrombophilic risk factors should be investigated and optimal therapeutic and prophylactic measures should be promptly taken in children with thrombosis.

Enoxaparin Reduces Catheter Associated Venous Thrombosis Following Infant Cardiac Surgery

BACKGROUND

Central venous catheter (CVC) related venous thrombosis (VT) following pediatric cardiac surgery increases the morbidity and mortality. Although VT prevention using low dose anticoagulation has proven ineffective, anticoagulation using high dose enoxaparin to achieve a therapeutic anti-xa level has not been studied. We hypothesized that high dose enoxaparin would reduce VT after pediatric cardiac surgery.

METHODS

Enoxaparin was administered to infants < 150 days when post-operative CVC duration was anticipated to extend beyond 5 days. The primary outcome was the rate of VT, re-exploration for bleeding, and post-operative red blood cell (RBC) transfusions per 1,000 CVC days.

RESULTS

From 2012-2019, 157 infants were treated with enoxaparin. Infants were divided into two groups: 1) SubTherapeutic (SubTher) (N = 51) - therapeutic anti-xa level (0.5-1.0 IU/mL) was not achieved, 2) Therapeutic (Ther) (N = 106) - therapeutic anti-xa level was achieved. Baseline demographics demonstrated a lower age at operation within the Ther group. The SubTher group had a higher VT rate/1,000 CVC days (8.2) compared to the Ther group (2.6; p=0.005). Re-exploration for bleeding was similar between groups. The number of post-operative RBC transfusions/1,000 CVC days was significantly greater in the SubTher group (109.4 vs. 81.6; p=0.008). Multivariate analysis demonstrated that higher median anti-xa levels reduced the risk of VT (OR 0.02, CI: 0.001, 0.63; p = 0.02).

CONCLUSIONS

This data suggests that enoxaparin treatment resulting in a therapeutic anti-xa level reduces post-operative CVC associated VT without increasing bleeding complications.

Comparative validation study of risk assessment models for pediatric hospital-acquired venous thromboembolism

BACKGROUND

Risk assessment models (RAMs) have been developed to identify children at high risk of hospital-acquired venous thromboembolism (HA-VTE). None have been externally validated nor compared.

OBJECTIVES

The objective was to compare performance of these RAMs by externally validating them using the Children's Hospital-Acquired Thrombosis (CHAT) Registry, ie, a multicenter database of children with radiographic-confirmed HA-VTE and corresponding controls.

PATIENTS/METHODS

Risk assessment models were included if the full logistic regression equation was available and all RAM variables were collected in the CHAT Registry. A random sample of 200 cases and 200 controls was selected. The performance of the RAMs was assessed for discrimination using area under the receiver operating characteristic curves (AUROC), and calibration using plots, slopes, and intercepts, and the Hosmer-Lemeshow test.

RESULTS

Three RAMs were included. Each had excellent discrimination with AUROC ≥ 0.85. However, calibration was generally poor, with calibration slopes significantly different from 1 (0.71, P < .001; 1.44, P = .002; 0.68, P < .001), intercepts significantly different from 0 (-1.64, P < .001; -0.62, P < .001; 0.78, P < .001), and Hosmer-Lemeshow test P < .001 for each. Exceptions included the Arlikar et al and Atchison et al RAMs for pediatric HA-VTE in non-intensive care unit (ICU) patients and ICU patients, respectively, despite derivation from ICU and non-ICU patients, respectively. In these subpopulations, both showed excellent discrimination and good calibration.

CONCLUSION

Given the lack of adequate calibration for evaluated RAMs, further investigation and refinement of RAMs for pediatric HA-VTE is needed prior to application of a RAM in a clinical setting or risk-stratified clinical trial of primary thromboprophylaxis against HA-VTE in children.

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.

Central Venous Catheter-Related Deep Vein Thrombosis in the Pediatric Cardiac Intensive Care Unit

BACKGROUND

Central venous catheter (CVC) use is common in the management of critically ill children, especially those with congenital heart disease. CVCs are known to augment the risk of deep vein thrombosis (DVT), but data on CVC-associated DVTs in the pediatric cardiac intensive care unit (CICU) are limited. In this study, we aim to identify the incidence of and risk factors for CVC-related DVT in this high-risk population, as its complications are highly morbid.

MATERIALS AND METHODS

The PC4 database and a radiologic imaging database were retrospectively reviewed for the demographics and outcomes of patients admitted to the Texas Children's Hospital CICU requiring CVC placement, as well as the incidence of DVT and its complications.

RESULTS

Between January 2017 and December 2017, 1215 central lines were placed over 851 admissions. DVT was diagnosed in 8% of admissions with a CVC, 29% of which demonstrated thrombus in the inferior vena cava. The risk factors significantly associated with DVT included the presence of >1 line, higher total line hours, longer intubation times, and extended CICU stay. A diagnosis of low cardiac output syndrome, sepsis, central line-associated bloodstream infection, and cardiac catheterization were also significant risk factors. Interestingly, cardiac surgery with cardiopulmonary bypass appeared to be protective of clot development. DVT was a highly significant risk factor for mortality in these patients.

CONCLUSIONS

CVC-related DVTs in critically ill children with congenital heart disease are associated with higher risks of morbidity and mortality, highlighting the need for well-designed studies to determine the best preventative and treatment strategies and to establish guidelines for appropriate monitoring and follow-up of these patients.

Thrombosis in Children: Approach to Anatomic Risks, Thrombophilia, Prevention, and Treatment

Pediatric venous thromboembolism (VTE) is increasing in incidence but minimal data exist for best practices regarding therapy, use of thrombophilia testing, and management of long-term complications. Classification schema use anatomic location and presence of clinical or thrombophilic inciting factors. There are a small number of risk-assessment and risk-modeling systems for incident VTE, but all suffer from low numbers, single-institution design, and lack of prospective validation. Acute treatment is limited to heparin products and thrombolysis may be indicated in specific situations. In addition, chronic postthrombotic comorbidities are expected to increase in incidence and lack evidence-based treatment paradigms.

Epidemiology and Risk Assessment of Pediatric Venous Thromboembolism

The incidence of diagnosed venous thromboembolism (VTE) has been increasing concurrent with advances in technology and medical care that enhance our ability to treat pediatric patients with critical illness or complex multiorgan system dysfunction. Although the overall incidence of VTE is estimated at 0.07-0.49 per 10,000 children, higher rates are observed in specific populations including hospitalized children, those with central venous catheters (CVCs) or patients convalescing from a major surgery. While the absolute number of pediatric VTE events may seem trivial compared to adults, the increasing incidence, associated with increased mortality and morbidity, the availability of novel therapies, and the impact on the cost of care have made investigation of VTE risk factors and prevention strategies a high priority. Many putative risk factors for pediatric VTE have been reported, primarily from single-institution, retrospective studies which lack appropriate methods for verifying independent risk factors. In addition, some risk factors have inconsistent definitions, which vex meta-analyses. CVCs are the most prevalent risk factors but have not consistently been assigned the highest level of risk as defined by odds ratios from retrospective, case-control studies. Few risk-assessment models for hospital-acquired pediatric VTE have been published. Some models focus exclusively on hospitalized pediatric patients, while others target specific populations such as patients with cancer or severe trauma. Multicenter, prospective studies are needed to identify and confirm risk factors in order to create a pediatric risk-assessment tool and optimize preventive measures and reduce unintended harm.

Thrombotic complications in children from short-term percutaneous central venous catheters: what can we do?

The reported incidence of venous thromboembolism (VTE) in children has increased dramatically over the past decade, and the primary risk factor for VTE in neonates and infants is the presence of a central venous catheter (CVC). Although the associated morbidity and mortality are significant, very few trials have been conducted in children to guide clinicians in the prophylaxis, diagnosis, and treatment of CVC-related VTE. Furthermore, pediatric guidelines for prophylaxis and management of VTE are largely extrapolated from adult data. How then should the anesthesiologist approach central access in children of different ages to lessen the risk of CVC-related VTE or in children with prior thrombosis and vessel occlusion? A comprehensive review of the pediatric and adult literature is presented with the goal of assisting anesthesiologists with point-of-care decision-making regarding the risk factors, diagnosis, and treatment of CVC-related VTE. Illustrative cases are also provided to highlight decision-making in varying situations. The only risk factor strongly associated with CVC-related VTE formation in children is the duration of the indwelling CVC. Several other factors show a trend toward altering the incidence of CVC-related VTE formation and may be under the control of the anesthesiologist placing and managing the catheter. In particular, because children with VTE may live decades with its sequelae and chronic vein thrombosis, careful consideration of lessening the risk of VTE is warranted in every child. Further studies are needed to form a clearer understanding of the risk factors, prophylaxis, and management of CVC-related VTE in children and to guide the anesthesiologist in lessening the risk of VTE.

Blood glucose as a marker of venous thromboembolism in critically ill children

BACKGROUND

The ability to predict the development of venous thromboembolism is highly desirable.

OBJECTIVE

We aim to determine the association between hyperglycemia and venous thromboembolism in non-diabetic critically ill children.

PATIENTS/METHODS

We conducted a retrospective cohort study that included children in the pediatric intensive care unit on a vasopressor or mechanical ventilator and without history of diabetes mellitus or prior diagnosis of thrombosis. Based on maximum blood glucose > 150 mg dL(-1) while admitted to the unit, children were categorized as hyperglycemic or non-hyperglycemic. The primary outcome was development of venous thromboembolism while admitted to the unit. We determined the association between hyperglycemia and venous thromboembolism using logistic regression models adjusting for selected subject characteristics.

RESULTS

Of the 789 subjects analyzed, 34 subjects developed venous thromboembolism (incidence, 4.3%; 95% confidence interval, 3-6%). Venous thromboembolism was more likely to develop in hyperglycemic subjects compared with non-hyperglycemic subjects. A total of 31 subjects (6.2%; 95% confidence interval, 4.2-8.7%) developed venous thromboembolism after becoming hyperglycemic compared with three non-hyperglycemic subjects with venous thromboembolism (1%; 95% confidence interval, 0.2-3%). When adjusted for age, diagnosis, presence of central venous catheter, prophylactic antithrombotic use and severity of illness, the odds ratio of venous thromboembolism with hyperglycemia was 4.1 (95% confidence interval, 1.2-14.1). For every 10 mg dL(-1) increase in maximum blood glucose, the adjusted odds ratio of venous thromboembolism was 1.04 (95% confidence interval, 1.01-1.06).

CONCLUSION

Hyperglycemia is associated with venous thromboembolism in critically ill non-diabetic children. Maximum blood glucose is a potential predictor of venous thromboembolism in this population.

Venous thromboembolism in critically ill children

PURPOSE OF REVIEW

To review the current literature on venous thromboembolism (VTE) in critically ill children.

RECENT FINDINGS

There is an increasing concern for VTE and its complications in critically ill children. Critically ill children are at increased risk of thromboembolism because of the treatment that they are receiving and their underlying condition. A complex relationship exists between thrombosis and infection. A thrombus is a nidus for infection, while infection increases the risk of thrombosis. Pediatric-specific guidelines for the prevention and treatment of thromboembolism are lacking. Current guidelines are based on the data from adults. Novel anticoagulants are now available for use in adults. Studies are ongoing to determine their safety in children. Risk assessment tools have recently been developed to determine the risk of thromboembolism in critically ill children. Certain molecules are associated with thromboembolism in adults.

SUMMARY

Pediatric critical care practitioners should be cognizant of the importance of VTE in critically ill children to allow early identification and treatment. Adequately powered clinical trials are critically needed to generate evidence that will guide the treatment and prevention of thromboembolism in critically ill children. Risk assessment tools that incorporate biomarkers may improve our ability to predict the occurrence of thromboembolism in critically ill children.