Antithrombotic therapy in children

Enoxaparin treatment dosing for venous thromboembolism in pediatric patients with obesity

BACKGROUND

The optimal enoxaparin dosing for treatment of venous thromboembolism (VTE) in pediatric patients with obesity remains uncertain. We described the mean enoxaparin dose required to attain anti-factor Xa (anti-Xa) levels of 0.5-1 unit/mL in pediatric patients with obesity.

METHODS

Pediatric patients with obesity (body mass index [BMI] ≥95th percentile) who received treatment dose of enoxaparin from 2013 to 2022 and had at least one appropriately timed anti-Xa level were retrospectively evaluated. Daily enoxaparin dose required to achieve an anti-Xa level of 0.5-1 unit/mL was reviewed and compared by the severity of obesity. The correlation coefficients between enoxaparin dose requirement and BMI, BMI percentile, and weight were measured by Spearman's rank correlation coefficient.

RESULTS

Pediatric patients with obesity (n = 89) required a mean enoxaparin dose of 0.8 ± 0.18 mg/kg twice daily to attain a therapeutic anti-Xa level. Children with BMI 95th-99th percentile and weight ≤100 kg achieved the target level on a significantly higher weight-based enoxaparin dose compared to BMI greater than 99th percentile (0.95 ± 0.15 vs. 0.75 ± 0.15 mg/kg twice daily; p < .001) and weight greater than 100 kg (0.95 ± 0.14 vs. 0.7 ± 0.12 mg/kg twice daily; p < .001). BMI, BMI percentile, and weight showed a moderate to strong negative correlation with enoxaparin dose requirement.

CONCLUSIONS

Pediatric patients with obesity required a lower weight-based dose of enoxaparin to achieve a therapeutic anti-Xa than the recommended starting dose of 1 mg/kg twice daily for treatment of VTE. Among obesity indices, weight showed the strongest negative correlation with total daily enoxaparin requirement.

Evaluation of the Safety and Efficacy of Enoxaparin Once-Daily Versus Twice-Daily Dosing for Prophylaxis in Pediatric Patients

OBJECTIVES

Enoxaparin for the prevention of venous thromboembolism (VTE) in pediatric patients is -typically dosed twice a day. The use of once-daily dosing like that used in adult patients is limited because of a lack of safety and efficacy data. The aim of this study was to evaluate the safety and efficacy of -once-daily versus twice-daily dosing of enoxaparin for pediatric VTE prophylaxis based on incidence of thrombotic and bleeding events.

METHODS

This was a 3-year retrospective chart review of enoxaparin received for VTE prophylaxis at -Cohen Children's Medical Center, New Hyde Park, NY. Exclusion criteria were age 18 years or older, and renal dysfunction.

RESULTS

A total of 177 enoxaparin courses (81 in the once-daily and 96 in the twice-daily group) were included. The median dose in the once-daily group was 0.68 mg/kg/dose with dose capping at 40 mg/dose in 70% of patients. One patient in the once-daily group had a VTE, whereas no patients in the twice-daily group experienced a VTE. One major bleeding event occurred in the once-daily group (p = 0.46); however, minor bleeding events were comparable between the 2 groups (p = 0.69).

CONCLUSIONS

Once-daily enoxaparin prophylaxis appears to be safe and effective based on minimal -differences in incidence of thrombotic and bleeding events when compared to twice-daily dosing. Based on this study, it may be reasonable to consider once-daily enoxaparin dosing for prophylaxis, especially in older children. A larger multicenter cohort study evaluating once-daily dosing for prophylaxis is warranted to validate the safety and efficacy specifically for risk-based dosing strategies.

Risk factors for serious adverse events related to vitamin K antagonists in children with congenital or acquired heart disease: a prospective cohort study

OBJECTIVES

To assess the occurrence of thrombosis and major bleeding in children with congenital or acquired heart disease (CAHD) treated with VKA and to identify risk factors for these serious adverse events (SAE).

STUDY DESIGN

All children enrolled in our VKA dedicated educational program between 2008 and 2022 were prospectively included. The time in therapeutic range (TTR) was calculated to evaluate the stability of anticoagulation. Statistical analysis included Cox proportional hazard models.

RESULTS

We included 405 patients. Median follow-up was 18.7 (9.3-49.4) months. The median TTR was 83.1 % (74.4 %-95.3 %). No deaths occurred because of bleeding or thrombotic events. The incidences of thrombotic and major bleeding events were 0.9 % (CI95 % [0.1-1.8]) and 2.3 % (CI95 % [0.9-3.8]) per patient year, respectively. At 1 and 5 years, 98.3 % (CI95 % [96.2 %-99.2 %]) and 88.7 % (CI95 % [81.9 % 93.1 %]) of patients were free of any SAE, respectively. Although the mechanical mitral valve (MMV) was associated to major bleeding events (HR = 3.1 CI95 % [1.2-8.2], p = 0.02) in univariate analysis, only recurrent minor bleeding events (HR = 4.3 CI95 % [1.6-11.7], p < 0.01) and global TTR under 70 % (HR = 4.7 CI95 % [1.5-15.1], p < 0.01) were independent risk factors in multivariable analysis. In multivariable analysis, giant coronary aneurysms after Kawasaki disease (HR = 7.8 [1.9-32.0], p = 0.005) was the only risk factor for thrombotic events.

CONCLUSION

Overall, VKA therapy appears to be safe in children with CAHD. Suboptimal TTR, regardless of the indication for VKA initiation, was associated with bleeding events.

[Illustrated case study of a patient with pediatric multisystem inflammatory syndrome]

Between November 2020 and June 2021, twelve children were treated at a university hospital in western France for pediatric multisystem inflammatory syndrome (PIMS). While the clinical presentation may have been reminiscent of Kawasaki disease, PIMS, a new nosological entity, was mentioned in the media in the context of the Covid-19 pandemic. In 2023, research into this syndrome will continue in France and Europe.

Evaluation of a Treatment-Dose Enoxaparin Protocol for Patients With Obesity

BACKGROUND

Treatment-dose enoxaparin is not well studied in obese patients. Guidelines suggest that obese patients receiving enoxaparin therapy for acute venous thromboembolism (VTE) should receive a standard initial dose, 1 mg/kg, based on actual body weight. It is possible that this dosing strategy in obese patients may be overestimated, leading to a higher bleeding risk compared to non-obese patients.

OBJECTIVE

To gather data regarding enoxaparin treatment dosing and anti-Xa level monitoring in patients who are obese to guide dose adjustments.

METHODS

A single-center, retrospective chart review that included patients who were ordered treatment-dose enoxaparin and had a BMI ≥ 40 kg/m², which resulted in an automatic pharmacy consult.The primary endpoint of this study was incidence of bleeding.

RESULTS

The analysis included 102 patients. Most patients (92.1%) had a BMI of ≥ 40-60 kg/m² while 7.8% of patients had a BMI of > 60 kg/m². The average initial and final doses were 1.0 ± 0.1 mg/kg and 0.9 ± 0.2 mg/kg, respectively. The incidence of bleeding was 4.9%. The average dose for those that bled was 0.7 ± 0.1 mg/kg. On average, patients who bled had higher BMIs than patients who did not bleed (51.6 kg/m² vs. 48.0 kg/m²). Of the 71 patients with an initial anti-Xa level, 42 of the levels were considered supratherapeutic (59.2%).

CONCLUSION

A 1 mg/kg starting dose of enoxaparin may be too high for patients who are obese as many patients required an adjustment to their dose after initial anti-Xa levels.

Cerebral Sinovenous Thrombosis in Infants and Children: A Practical Approach to Management

Cerebral sinovenous thrombosis (CSVT) is a rare, yet potentially devastating disorder, associated with acute complications and long-term neurologic sequelae. Consensus-based international pediatric CSVT treatment guidelines emphasize early clinical-radiologic recognition and prompt consideration for anticoagulation therapy. However, lack of clinical trials has precluded evidence-based patient selection, anticoagulant choice, optimal monitoring parameters and treatment duration. Consequently, uncertainties and controversies persist regarding anticoagulation practices in pediatric CSVT. This review focuses on commonly encountered issues that continue to pose questions and raise debates regarding anticoagulation therapy among pediatric neurologists and hematologists.

Outcomes of Prophylactic Enoxaparin Against Venous Thromboembolism in Hospitalized Children

OBJECTIVES

To assess the biochemical and clinical outcomes of hospitalized children who received prophylactic enoxaparin.

METHODS

We conducted a retrospective observational study of hospitalized children aged <18 years who received prophylactic enoxaparin against hospital-acquired venous thromboembolism (HA-VTE). Weight-based enoxaparin dosing was administered using a pharmacy-driven protocol, which later included a low molecular weight, anti-Xa level directed-dose adjustment strategy. Primary biochemical and clinical outcomes were achievement of goal anti-Xa range of 0.2 to 0.5 IU/mL and development of HA-VTE, respectively. Secondary clinical outcome was development of clinically relevant bleed.

RESULTS

We analyzed 194 children with 13 (6.7%) infants aged <1 year and 181 (93.3%) older children aged ≥1 year. After the initial dose, only 1 (11.1%) infant, but 62 (57.9%) older children, achieved goal. Median number of anti-Xa levels until goal was 2 (interquartile range: 2-3) in infants and 1 (interquartile range: 1-2) in older children (P = .01). HA-VTE developed in 2 (15.4%) infants and 9 (5.0%) older children. Among children with anti-Xa level, HA-VTE developed less frequently in children who achieved (2.1%) than in those who did not achieve (13.6%) goal (P = .046). A total of 4 (2.1%) older children and no infants developed clinically relevant bleed. Among children with anti-Xa level, frequency of bleeding was comparable between children who did (3.2%) and did not achieve (0%) goal (P >.99).

CONCLUSIONS

Our findings suggest the effectiveness and safety of an anti-Xa level directed strategy of prophylactic enoxaparin. However, this strategy should be investigated in prospective controlled studies.

Managing Antiphospholipid Syndrome in Children and Adolescents: Current and Future Prospects

Pediatric antiphospholipid syndrome (APS) is a rare acquired multisystem autoimmune thromboinflammatory condition characterized by thrombotic and non-thrombotic clinical manifestations. APS in children and adolescents typically presents with large-vessel thrombosis, thrombotic microangiopathy, and, rarely, obstetric morbidity. Non-thrombotic clinical manifestations are frequently seen in pediatric APS and may be present even before the vascular thrombotic events occur. We review insights into the pathogenesis of APS and discuss potential targets for therapy. The identification of multiple immunologic abnormalities in patients with APS reveals molecular targets for current or future treatment. Management strategies, especially for APS in adolescents, require screening for additional prothrombotic risk factors and consideration of counseling regarding contraceptive strategies, lifestyle recommendations, treatment adherence, and mental health issues associated with this autoimmune thrombophilia. The main goal of therapy in pediatric APS is the prevention of thrombosis. The management of acute thrombosis events in children and adolescents is the same as for primary APS, which involves isolated occurrences, and secondary APS, which is seen in association with another autoimmune disease, e.g., systemic lupus erythematosus. A pediatric hematologist should be consulted so other differential thrombophilic conditions can be eliminated. Therapy includes unfractionated heparin or low-molecular-weight heparin followed by vitamin K antagonists. Treatment of catastrophic APS involves triple therapy (anticoagulation, intravenous corticosteroid pulse therapy, and plasma exchange) and may include intravenous immunoglobulin for children and adolescents with this condition. New drugs such as eculizumab and sirolimus seem to be promising drugs for APS.

Enoxaparin Dose Requirements to Achieve Therapeutic Low-molecular-weight Heparin Anti-factor Xa Levels in Infants and Young Children

INTRODUCTION

Enoxaparin is commonly used to treat pediatric thrombosis. Several small retrospective studies have suggested that infants and young children require higher enoxaparin doses to achieve therapeutic anti-factor Xa levels compared with adults.

MATERIALS AND METHODS

This is a retrospective study of hospitalized children who received enoxaparin for the treatment of thrombosis at a free-standing children's hospital. The primary objective was to ascertain the enoxaparin dose required to achieve an anti-factor Xa level of 0.5 to 1.0 U/mL among 4 age groups in a large cohort of infants and young children between 60 days and 5 years of age.

RESULTS

A total of 176 infants and children were evaluated. The majority of patients were less than 1 year of age (n=104). An inverse relationship between enoxaparin dose needed to achieve therapeutic anti-factor Xa levels and patient age was noted, particularly in the first year of life. Patients who were 60 days to less than 7 months at the time of enoxaparin initiation (n=73) required the highest mean dose among the age groups at 1.73 mg/kg subcutaneously every 12 hours (P<0.0001).

CONCLUSION

Infants and young children require higher doses of enoxaparin to achieve therapeutic anti-factor Xa levels compared with adults.

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.

Cancer-Associated Venous Thromboembolism Treatment With Anti-Xa Versus Weight-Based Enoxaparin: A Retrospective Evaluation of Safety and Efficacy

BACKGROUND

Venous thromboembolism (VTE) is a complication of cancer, for which low-molecular-weight heparin (LMWH) remains the preferred anticoagulant. Enoxaparin is traditionally dosed using weight. In certain populations, monitoring anti-Xa levels for therapeutic effect provides pharmacokinetic guidance for dose adjustments. There is a paucity of data regarding anti-Xa-directed enoxaparin dosing for treatment of VTE in patients with cancer.

OBJECTIVE

This study aims to evaluate efficacy (recurrent VTE) and safety (major bleed) between enoxaparin anti-Xa-guided dose adjustments and weight-based dosing in patients with cancer-associated VTE.

METHODS

This single-center, retrospective cohort study examined patients treated with enoxaparin for cancer-associated VTE using data from electronic health records.

RESULTS

There were 674 patients who met the inclusion criteria, with 283 receiving anti-Xa-directed dose adjustments. Recurrent VTE, major bleed, or all-cause death occurred in 102 of 283 patients (36%) in the anti-Xa cohort and 166 of 391 patients (42.5%) in the weight-based cohort (hazard ratio [HR] = 0.73; 95% CI = 0.57-0.93; P = 0.01). When death was removed from the composite end point, there was no significant difference between the cohorts in recurrent VTE or major bleed (HR = 1.18; P = 0.38). In the anti-Xa cohort, a total of 1584 anti-Xa peak levels were collected, with 1324 (83.6%) drawn correctly in relation to enoxaparin administration. Of those, 714 (53.9%) were within therapeutic range.

CONCLUSION AND RELEVANCE

Patients with cancer receiving anti-Xa-guided enoxaparin dose adjustments for initial VTE, compared with weight-based dosing, had no significant difference in the rate of recurrent VTE or major bleed.

Fermentation optimization, purification and biochemical characterization of ι-carrageenase from marine bacterium Cellulophaga baltica

The ι-carrageenan degrading marine bacterium, Cellulophaga baltica, was isolated from the surface of a filamentous red alga Vertebrata fucoides. Maximum ι-carrageenase production was optimized by single-factor experiments. Optimal fermentation conditions were 1.6 g/L furcellaran, 4 g/L yeast extract as carbon sources, 5 g/L sea salt, and 48 h of incubation time at 20 °C. Extracellular ι-carrageenase from the culture supernatant was purified by ultrafiltration, ammonium sulfate precipitation, and finally by anion-exchange chromatography, showed a 26-fold increase in specific activity as compared to that in the crude enzyme. According to the results from SDS-PAGE and HPLC-SEC, the molecular weight of the purified enzyme was estimated to be 31 kDa. The purified enzyme showed the maximum specific activity of 571 U/mg at 40 °C and pH 7.5-8.0. It maintained 73% of the total activity below 40 °C and 90% of its total activity at pH 7.2. Notably, the enzyme is a cold-adapted ι-carrageenase, which showed 33.4% of the maximum activity at 10 °C. The enzyme was stimulated by Na⁺, K⁺, and NH₄⁺, whereas Ca²⁺, Mg²⁺, Fe³⁺, sea salt, and EDTA acted as enzyme inhibitors.

Thrombolytic therapy in preterm infants: Fifteen-year experience

OBJECTIVE

To report a single-center experience with thrombolytic therapy using recombinant tissue plasminogen activator (rt-PA) in preterm neonates with severe thrombotic events, in terms of thrombus resolution and bleeding complications.

STUDY DESIGN

This retrospective study included 21 preterm neonates with severe venous thrombotic events admitted to the neonatal intensive care unit, identified in our pharmacy database from January 2001 to December 2016, and treated with rt-PA until complete or partial clot lysis, no-response or bleeding complications. Our primary outcome was thrombus resolution.

RESULTS

Twenty-one preterm neonates were treated with rt-PA for an average of 2.9 cycles. Seventeen patients (80.9%) had superior vena cava thrombosis and superior vena cava syndrome. All patients had a central venous catheter, parenteral nutrition, mechanical ventilation, and sepsis. Fifteen patients (71.4%) were extremely preterm, 11 (52.4%) were extremely low birth weight, and seven (33.3%) were very low birth weight. The patency rate was 85.7%, complete lysis occurred in 11 (52.4%) patients, and partial lysis in seven (33.3%). Minor bleeding occurred in five (23.8%) patients, three patients (14.2%) had clinically relevant nonmajor bleeding events, and major bleeding occurred in six (28%) patients.

CONCLUSION

In this study, the rate of thrombus resolution in preterm neonates treated with rt-PA were similar to the percentages reported in children and adolescents, with a high rate of bleeding. Therefore, rt-PA thrombolytic therapy should only be considered as a treatment option for severe life-threatening thrombosis in premature neonates for whom the benefits of the thrombolytic treatment outweigh the risks of bleeding.

Development of a perioperative venous thromboembolism prophylaxis algorithm for pediatric orthopedic surgical patients

Venous thromboembolism (VTE) has been recognized as a rare but potentially serious complication in pediatric orthopedic patients. However, standardized guidelines for screening and management of at-risk patients do not exist. The aim of the study was to develop a VTE prophylaxis screening tool for postoperative orthopedic patients after conducting an institutional needs assessment survey. A needs assessment survey was conducted after institutional ethics board approval. Development of perioperative VTE prophylaxis algorithm for pediatric orthopedic surgical patients was planned after thorough literature review, consultation with national and international experts as well as using a modified nominal and consensus development conference (serial meetings) method for reaching a consensus. NAS as well as discussion with stakeholders indicated support for development of perioperative VTE prophylaxis algorithm for orthopedic patients. Using above methods, a VTE prophylaxis algorithm was developed and implemented at IWK Health Center. The present study involved development of a perioperative VTE prophylaxis algorithm for pediatric orthopedic surgical patients that could be easily and rapidly administered as a point of care assessment tool.

Treatment of venous thromboembolism in pediatric patients

Venous thromboembolism (VTE) is rare in healthy children, but is an increasing problem in children with underlying medical conditions. Pediatric VTE encompasses a highly heterogenous population, with variation in age, thrombosis location, and underlying medical comorbidities. Evidence from pediatric clinical trials to guide treatment of VTE is lacking so treatment is often extrapolated from adult trials and expert consensus opinion. Aspects unique to children include developmental hemostasis and the major role of central venous access devices. There is an absence of information regarding the optimal target levels of anticoagulation for neonates and infants and lack of suitable drug formulations. Anticoagulants, primarily low-molecular-weight heparin and warfarin, are used to treat children with symptomatic VTE. These drugs have significant limitations, including the need for subcutaneous injections and frequent monitoring. Randomized clinical trials of direct oral anticoagulants in pediatric VTE are ongoing, with results anticipated soon. These trials will provide new evidence and options for therapy that have the potential to improve care. International collaborative registries offer the ability to study outcomes of rare subgroups of pediatric VTE (eg, renal vein thrombosis), and will be important to ultimately guide therapy in a more disease-specific manner.

Retrospective comparison of two enoxaparin dosing and monitoring protocols at a pediatric hospital

PURPOSE

The study analyzes the effectiveness and safety of a higher than standard enoxaparin dosing protocol implemented for pediatric patients requiring initiation of therapeutic anticoagulation.

METHODS

A retrospective review of 2 enoxaparin dosing and monitoring protocols was performed. The standard protocol used 1.5 mg/kg/dose (in patients <3 months of age) and 1 mg/kg/dose (in patients ≥3 months of age) with anti-Xa monitoring following the first dose. The high-dose protocol was implemented at 1.7 mg/kg/dose (in patients <3 months of age), 1.5 mg/kg/dose (in patients 3 through 11 months of age), 1.2 mg/kg/dose (in patients 1 through 4 years of age), and 1.1 mg/kg/dose (in patients 5 through 17 years of age), with anti-Xa monitoring after the second dose. Primary outcomes were number of dosing changes prior to and time to first target anti-Xa level. Secondary outcomes included percentage of patients with anti-Xa levels above target level.

RESULTS

The median number of dose changes required to achieve a target anti-Xa level was 1 (interquartile range [IQR], 0-1.5) and 0 (IQR, 0-1) for the standard-dose (n = 87) and high-dose groups (n = 132) (p = 0.17), respectively. The median number of dose adjustments to achieve target anti-Xa levels in the 3 through 11 months of age subgroup declined from 2 (IQR, 1-3.25) to 0 (IQR, 0-1) in the standard- versus high-dose groups, respectively (p < 0.01). No difference was seen in other age subgroups. Patients with above-target levels did not differ statistically between groups.

CONCLUSION

Initiating enoxaparin at higher doses in pediatric patients may result in fewer dosing changes than standard dosing. Benefit was demonstrated for the 3-11 months of age high-dose subgroup. Across all groups, the high-dose strategy was safe and did not result in a statistically significant increase in above-target levels.

A Critical Evaluation of Enoxaparin Dose Adjustment Guidelines in Children

OBJECTIVES

The purposes of this study are to perform a large-scale evaluation of the standardized dosage adjustment nomogram recommended by the American College of Chest Physicians (CHEST) for the management of enoxaparin in hospitalized pediatric patients and to determine the necessity of routine and repeated anti-factor Xa (anti-Xa) levels.

METHODS

A retrospective cohort study was designed, and charts were reviewed in a single tertiary care institution for all patients who received enoxaparin between October 1, 2010, through September 30, 2016. Patients were included if they were receiving treatment doses of enoxaparin according to the pediatric CHEST guidelines, had a subtherapeutic or supratherapeutic anti-Xa level drawn at 3.5 to 6 hours after a dose, had a dose changed in an attempt to attain a therapeutic anti-Xa level, and had a second anti-Xa level drawn 3.5 to 6 hours after the dose change. Descriptive statistical methods were used to characterize the ability of dose adjustment via a nomogram to attain an anti-Xa of 0.5 to 1 unit/mL.

RESULTS

A total of 467 patients were identified who received the appropriate initial dose and dosage adjustment and whose levels were drawn according to the CHEST guidelines. In patients who had an initial anti-Xa level of <0.35 units/mL and received the nomogram recommended dose increase of 25% ± 5%, 28 out of 96 patients (29.2%) reached therapeutic levels. Of 197 patients who had an initial anti-Xa level between 0.35 and 0.49 units/mL and who received the nomogram recommended dose increase of 10% ± 5%, 116 (58.9%) reached therapeutic levels. Of 50 patients with an initial anti-Xa level between 1.1 and 1.5 units/mL and who received the nomogram dose decrease of 20% ± 5%, 31 (62%) reached therapeutic levels.

CONCLUSIONS

The current dosage adjustment nomogram recommended by the CHEST guidelines does not reliably lead to therapeutic anti-Xa levels when used to adjust enoxaparin doses in pediatric patients.

A systematic review of paediatric deep venous thrombolysis

Objectives

The aim was to assess the effectiveness and safety of catheter-directed thrombolysis in children with deep venous thrombosis and to evaluate its long-term effect.

Method and results

EMBASE, Medline and Cochrane databases were searched to identify studies in which paediatric acute deep venous thrombosis patients received thrombolysis. Following title and abstract screening, seven cohort studies with a total of 183 patients were identified. Technical success was 82% and superior in regional rather than systemic thrombolysis (p < 0.00001). One cohort study identified significant difference in thrombus resolution at one year between thrombolytic and anticoagulant groups (p = 0.01). The complication rate was low, with incidence rates of major bleeding, pulmonary embolism and others at 2.8%, 1.8% and 8.4%, respectively. The overall post-thrombotic syndrome rate was 12.7%. The incidence of re-thrombosis ranged from 12.3% to 27%.

Conclusion

Thrombolysis for paediatric deep venous thrombosis is an effective and relatively safe therapeutic option, lowering the incidence of post-thrombotic syndrome and deep venous thrombosis recurrence.

[Thromboembolic disease in pediatric oncology]

The survival rate of children with cancer is now close to 80 %, as a result of continuous improvement in diagnostic and treatment procedures. Prevention and treatment of treatment-associated complications is now a major challenge. Thromboembolic venous disease, due to multifactorial pathogenesis, is a frequent complication (up to 40 % asymptomatic thrombosis in children with cancer), responsible for significant morbidity. Predominantly in children with acute lymphoblastic leukemia, lymphoma, or sarcoma, thromboembolic disease justifies primary prophylaxis in certain populations at risk, whether genetic or environmental. The curative treatment, well codified, is based on the administration of low-molecular-weight heparin. In the absence of robust pediatric prospective studies, this article proposes a concise decision tree summarizing the preventive and curative strategy.

Safe Use of Low-Molecular-weight Heparin in Pediatric Acute Lymphoblastic Leukemia and Lymphoma Around Lumbar Punctures

Children with acute lymphoblastic leukemia or lymphoma (ALL) undergo multiple lumbar punctures (LPs) and frequently require low-molecular-weight heparin (LMWH) for thromboembolic complications. We evaluated if withholding LMWH 24 hours before and after LPs prevented bleeding complications. Children (n=133) with ALL from who were: (1) treated at St. Jude Children's Research Hospital, (2) received LMWH (2×/day of ~1 mg/kg) between January 2004 until December 2012, and (3) underwent a LP were analyzed. Spinal hematoma was defined as a clinical suspicion leading to diagnostic imaging. Traumatic LP was defined as ≥10 red blood cells per microliter of cerebrospinal fluid. In 1708 LPs, no hematomas occurred. For each child treated with LMWH, the probability of experiencing a spinal hematoma during the entire ALL treatment course was 0% (95% confidence interval [CI], 0.0%-2.7%), and in each LP, assuming no intrapatient correlation, the probability of spinal hematoma was 0% (95% CI, 0.0%-0.2%). Traumatic LPs were more common when performed when children were not receiving LMWH therapy (odds ratio [OR], 1.5; 95% CI, 1.1-2.2) which may be explained by clinician optimization of known risk factors for traumatic cerebrospinal fluid before the procedures. Withholding LMWH for 24 hours before and after LPs in children being treated for ALL is safe.

Clinical Feasibility of Monitoring Enoxaparin Anti-Xa Concentrations: Are We Getting It Right?

Background: Anti-Xa monitoring is utilized to measure the extent of anticoagulation in certain patient populations receiving enoxaparin. It is essential to accurately obtain this pharmacodynamic marker for safe and effective anticoagulation management. Objectives: To determine the frequency of correctly drawn anti-Xa concentrations in accordance with predefined institutional criteria and to determine the number of dose adjustments implemented based on incorrectly drawn anti-Xa concentrations. Methods: This was a retrospective, single-center, cohort study among adult patients who received treatment doses of enoxaparin with measured anti-Xa concentrations. Patients were excluded if they were pregnant, on hemodialysis, or received prophylactic dosing. Anti-Xa levels were defined as correctly measured if they were drawn 3 to 5 hours after the dose during steady state concentrations. Descriptive statistics were performed and analyzed via SPSS software. Results: Overall, 203 patients were reviewed and 59 patients with 74 anti-Xa levels were included. The majority of anti-Xa levels (57/74; 77%) were drawn incorrectly and often resulted in collection of repeat anti-Xa samples. There were 12 documented dose adjustments and approximately 42% (5/12) were based on incorrectly drawn anti-Xa levels. Anti-Xa levels were within target range approximately 45% of the time. Conclusions: Enoxaparin anti-Xa concentrations are frequently drawn incorrectly and dose adjustments are often performed based on these unsupported anti-Xa levels. This may present a potential risk to compromise patient safety.

Evaluation for inherited and acquired prothrombotic defects predisposing to symptomatic thromboembolism in children with acute lymphoblastic leukemia: a protocol for a prospective, observational, cohort study

BACKGROUND

Thromboembolism (TE) is a serious complication in children with acute lymphoblastic leukemia (ALL). The incidence of symptomatic thromboembolism is as high as 14% and case fatality rate of ~15%. Further, development of thromboembolism interferes with the scheduled chemotherapy with potential impact on cure rates. The exact pathogenesis of ALL-associated thromboembolism is unknown. Concomitant administration of asparaginase and steroids, two important anti-leukemic agents, is shown to increase the risk of ALL-associated TE. Dana-Farber Cancer Institute (DFCI) ALL studies reported ~10% incidence of thrombosis with significantly increased risk in older children (≥10 yrs.) and those with high-risk ALL. The majority (90%) of thromboembolic events occurred in the Consolidation phase of therapy with concomitant asparaginase and steroids when high-risk patients (including all older patients) receive higher dose steroids. Certain inherited and acquired prothrombotic defects are known to contribute to the development of TE. German investigators documented ~50% incidence of TE during therapy with concomitant asparaginase and steroids, in children with at least one prothrombotic defect. However, current evidence regarding the role of prothrombotic defects in the development of ALL-associated TE is contradictory. Although thromboprophylaxis can prevent thromboembolism, ALL and it's therapy can increase the risk of bleeding. For judicious use of thromboprophylaxis, identifying a population at high risk for TE is important. The risk factors, including prothrombotic defects, predisposing to thrombosis in children with ALL have not been defined.

METHODS

This prospective, observational cohort study aims to evaluate the prevalence of inherited prothrombotic defects in children with ALL treated on DFCI 05-01 protocol and the causal relationship of prothrombotic defects in combination with patient and disease-related factors to the development of TE. We hypothesize that the combination of prothrombotic defects and the intensive therapy with concomitant high dose steroids and asparaginase increases the risk of TE in older patients and patients with high-risk ALL.

DISCUSSION

The results of the proposed study will help design studies of prophylactic anticoagulant therapy. Thromboprophylaxis given to a targeted population will likely reduce the incidence of TE in children with ALL and ultimately improve their quality of life and prospects for cure.

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

OBJECTIVE

Subcutaneous enoxaparin is the mainstay anticoagulant in critically ill pediatric patients although it poses several challenges in this patient population. Enoxaparin infused IV over 30 minutes represents an attractive alternative, but there is limited experience with this route of administration in children. In this study, we assess dosing, anticoagulation quality, safety, and clinical efficacy of IV enoxaparin compared to subcutaneous enoxaparin in critically ill infants and children.

DESIGN

Retrospective single-center study comparing dosing, anticoagulation quality, safety, and clinical efficacy of two different routes of enoxaparin administration (IV vs subcutaneous) in critically ill infants and children. Key outcome measures included dose needed to achieve target antifactor Xa levels, time required to achieve target antifactor Xa levels, proportion of patients achieving target anticoagulation levels on initial dosing, number of dose adjustments, duration spent in the target antifactor Xa range, anticoagulation-related bleeding complications, anticoagulation failure, and radiologic response to anticoagulation.

SETTING

Tertiary care pediatric hospital.

PATIENTS

All children admitted to the cardiac ICU, PICU, or neonatal ICU who were prescribed enoxaparin between January 2014 and March 2016 were studied.

INTERVENTIONS

One hundred ten patients were identified who had received IV or subcutaneous enoxaparin and had at least one postadministration peak antifactor Xa level documented.

MEASUREMENTS AND MAIN RESULTS

Of the 139 courses of enoxaparin administered, 96 were therapeutic dose courses (40 IV and 56 subcutaneous) and 43 were prophylactic dose courses (20 IV and 23 subcutaneous). Dosing, anticoagulation quality measurements, safety, and clinical efficacy were not significantly different between the two groups.

CONCLUSIONS

Our study suggests that anticoagulation with IV enoxaparin infused over 30 minutes is a safe and an equally effective alternative to subcutaneous enoxaparin in critically ill infants and children.

Treatment of Deep Vein Thrombosis With Enoxaparin in Pediatric Cancer Patients Receiving Chemotherapy

There are few data regarding the use of enoxaparin in children undergoing myelosuppressive therapy for malignancies even though thrombosis is a known risk in pediatric patients with malignancies. Low-molecular-weight heparin such as enoxaparin has become widely used in adult patients with thrombosis. The purpose of this study was to review the utilization of low-molecular-weight heparin, enoxaparin (Lovenox), in children with cancer at our institution who had thrombosis while undergoing myelosuppressive chemotherapy. In particular we were interested in the efficacy of enoxaparin in these patients, and in whether these children were able to continue their chemotherapy without adjustment or interruption secondary to bleeding complications. We conducted a retrospective review from 1999 through April 1, 2004. Seven patients (4—17 years of age) were identified. Diagnosis included B-precursor acute lymphoblastic leukemia (ALL) (n=three), T-ALL, Hodgkin's disease, anaplastic large cell lymphoma, and rhabdomyosarcoma (n=one each). Six patients had a deep vein thrombus (DVT) or clot of the vena cava. One of these six patients also had a pulmonary embolus. One patient presented with manifestations of a unilateral cerebral vascular accident without evidence of DVT. Most patients were screened for known hypercoaguable abnormalities. Treatment was enoxaparin, 1—1.5 mg/kg/dose twice daily to maintain a heparin anti-Xa level of 0.5—1.5 IU/mL till clot resolution. The dose was then decreased to daily for a total of 3—6 months of therapy. All patients had resolution of their thrombosis within 1—2 months of initiation of enoxaparin, and none required delays or dose reduction of their chemotherapy regimens while on anticoagulation, though some were supported by blood and platelet transfusions. Enoxaparin was safely administered to this series of seven patients for thrombotic complications in children undergoing cancer chemotherapy.

Analysis of Enoxaparin Dose Titration at a Large, Tertiary Teaching Facility

Therapeutic drug monitoring of enoxaparin with antifactor Xa levels (AXALs) is recommended in some populations; however, the approach to dose titration is poorly described. Our study at a large, tertiary teaching facility examined the dose response to titration of enoxaparin based on AXAL. Patients from 2008 to 2012 receiving enoxaparin were included, provided 2 or more steady state AXAL were obtained within 30 days and that the enoxaparin was prescribed for treatment rather than prophylaxis. The primary outcome was the percentage of dose change required to obtain goal range AXAL following dose titration. Eighty-seven patients were available for analysis with the following key characteristics: renal dysfunction during treatment 72%, obesity 8%, and solid organ transplant 26%. Initial goal AXAL was attained in 27 (31%) patients, and ultimately 54 (62%) patients achieved goal AXAL. Of the 31 patients who had initial AXAL above goal, 13 (42%) patients reached goal with a median dose decrease of 24%. In the 29 patients who had an initial AXAL below goal, 11 (38%) achieved therapeutic AXAL with a median dose increase of 16%. The AXAL monitoring can guide enoxaparin titration with subtherapeutic or supratherapeutic AXAL and an increase or decrease of roughly 20% is suggested as an initial change.

Management of venous thrombosis in the pediatric patient

The incidence of venous thromboembolism in children has increased significantly over the past decade. The evaluation and management of the child with venous thromboembolism, while based on the adult experience, has its own particularities dictated by the differences in the hemostatic system of the newborn and child. The current review addresses the evaluation of pediatric patient with thrombosis as well as the established and emerging treatment interventions.

A retrospective analysis of outcomes of dalteparin use in pediatric patients: a single institution experience

BACKGROUND

Dalteparin is a commonly used low molecular weight heparin (LMWH) with extensive safety data in adults. With distinct advantages of once daily dosing and relative safety in renal impairment, it has been used off-label in pediatric practice; however, age-based dosing guidelines, safety and efficacy data in children are evolving.

OBJECTIVES

To report our institutional experience with the use of dalteparin in the treatment and prophylaxis of venous thromboembolism (VTE) in pediatric patients.

PATIENTS/METHODS

Retrospective chart review of all children (0-18years) that received dalteparin from December 1, 2000 through December 31, 2011. Doses per unit body weight per day (units/kg/day) were calculated for age-based group comparisons.

RESULTS

Of 166 patients identified, 116 (70%) received prophylactic doses while 50 (30%) received therapeutic doses of dalteparin. Infants (<1year) required significantly higher weight-based dosing to achieve therapeutic anti-Xa levels compared to children (1-10years) or adolescents (>10-18years) (mean dose units/kg/day; 396.6 versus 236.7 and 178.8 respectively, p<0.0001). Overall response rate, including complete and partial thrombus resolution, was 83%. Bleeding complications were minor and the rates were similar in therapeutic and prophylaxis patients. No significant differences in dosing or bleeding events were noted based on obesity or malignancy.

CONCLUSIONS

In our experience, dalteparin is effective for prophylaxis and therapy of VTE in pediatric patients. Dosing should be customized in an age-based manner with close monitoring of anti-Xa activity in order to achieve optimal levels, prevent bleeding complications, and to allow full benefit of prevention or therapy of thrombotic complications.

Evaluation of Enoxaparin Dosing and Monitoring in Pediatric Patients at Children's Teaching Hospital

OBJECTIVES

The primary objective of this study was to evaluate whether empirical enoxaparin doses according to Chest guidelines resulted in therapeutic antifactor Xa concentrations in pediatric patients. Secondary objectives were to determine the median enoxaparin dose that resulted in therapeutic anticoagulation, the median time to therapeutic concentrations, and the percentage of patients who experienced major bleeding.

METHODS

Patients in a tertiary medical center who were <18 years of age and received treatment doses of enoxaparin between July 2007 and June 2010 were included. Patients with <2 antifactor Xa concentrations or with only supratherapeutic concentrations and doses that were higher than recommended by the guidelines were excluded. Subgroup analysis was conducted by dividing children into 4 age groups: <2 months of age, 2 months to <1 year of age, 1 year to <3 years of age, and 3 to 17 years of age.

RESULTS

Thirty-two patients were included in the study. Thirty-seven percent of the patients achieved a therapeutic drug level with empirical dosing. The therapeutic dose ranged from 1 to 1.9 mg/kg in patients <1 year old, and 0.6 to 1.5 mg/kg in those =1 year of age. Comparison of the median therapeutic doses for patients 2 months to <1 year to that for patients =1 year old using the Mann-Whitney U test showed the median doses to be significantly difierent between the 2 groups (p=0.01). The antifactor Xa level became therapeutic on day 5 (median). There were no major bleeding events.

CONCLUSION

Less than 40% of patients were therapeutic with empirical dosing, which supports findings from other studies that suggest a need for modification of empirical treatment dosing of enoxaparin in children.

Pharmacogenetics of warfarin in a paediatric population: time in therapeutic range, initial and stable dosing and adverse effects

Warfarin is used in paediatric populations, but dosing algorithms incorporating pharmacogenetic data have not been developed for children. Previous studies have produced estimates of the effect of polymorphisms in Cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex subunit 1 (VKORC1) on stable warfarin dosing, but data on time in therapeutic range, initial dosing and adverse effects are limited. Participants (n=97) were recruited, and routine clinical data and salivary DNA samples were collected from all participants and analysed for CYP2C9*2, *3 and VKORC1-1639 polymorphisms.VKORC1 -1639 was associated with a greater proportion of the first 6 months' treatment time spent within the target International Normalised Ratio (INR) range, accounting for an additional 9.5% of the variance in the proportion of time. CYP2C9*2 was associated with a greater likelihood of INR values exceeding the target range during the initiation of treatment (odds ratio (OR; per additional copy) 4.18, 95% confidence interval (CI) 1.42, 12.34). CYP2C9*2 and VKORC1-1639 were associated with a lower dose requirement, and accounted for almost 12% of the variance in stable dose. VKORC1-1639 was associated with an increased likelihood of mild bleeding complications (OR (heterozygotes vs homozygotes) 4.53, 95% CI 1.59, 12.93). These data show novel associations between VKORC1-1639 and CYP2C9*2 and INR values in children taking warfarin, as well as replicating previous findings with regard to stable dose requirements. The development of pharmacogenomic dosing algorithms for children using warfarin has the potential to improve clinical care in this population.

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.

Assessment of the outcomes associated with periprocedural anticoagulation management in children with acute lymphoblastic leukemia

OBJECTIVE

To report the outcomes of an institutional protocol for periprocedural anticoagulant (AC) management in children with acute lymphoblastic leukemia (ALL).

STUDY DESIGN

Children being treated for ALL who received full-dose (therapeutic) anticoagulation before undergoing at least 1 lumbar puncture (LP) were included in this retrospective cohort study. The main outcome was the risk of traumatic LP; exploratory analysis included the risks of symptomatic spinal hematoma and progression/recurrence of the thrombotic event. Analyses were conducted using logistic regression analysis with a generalized estimating equation approach.

RESULTS

Twenty-two children with ALL receiving an AC underwent a total of 396 LPs. Although traumatic LP was associated with full-dose AC therapy in univariable analysis, a multiple logistic regression model controlling for other risk factors for traumatic LP showed that AC therapy was not significantly associated with the risk of traumatic LP when the ACs were held as per the institutional protocol. No patient developed symptomatic spinal hematoma. Exploratory analysis revealed that AC dose, a likely marker of thrombus burden, was significantly associated with progression/recurrence of the thrombotic event in univariable analysis.

CONCLUSION

In our cohort, recent AC therapy was not statistically associated with an increased risk of bleeding after LP when following a specific protocol for periprocedural AC management. The risk associated with the progression/recurrence of thromboembolic events requires further evaluation.

Axillary artery thrombosis in a neonate in utero: a case report

We describe a neonate of 38-week and 6-day gestation born by lower uterine cesarean section for breech presentation, where it was evident on delivery that there was significant edema of the right arm from the deltoid to the distal tips of the fingers. Doppler flow ultrasound revealed extensive arterial thromboembolus. Intravenous heparin was prescribed for three days at a dose of 27.5 U/kg/h, targeting an activated partial thromboplastin time (APTT) of 60–75 seconds, followed by a course of subcutaneous enoxaparin at a dose of 1.8 mg/kg and then 2 mg/kg twice daily, titrated to a factor Xa level of 0.5–1.0 U/mL for another three days. Significant clinical improvement occurred and the child was eventually, discharged on subcutaneous enoxaparin. Magnetic resonance imaging showed multiple intracranial abnormalities. At five months increased upper limb tone, brisk reflexes, and small head circumference were noted. At one year, increased tone and increased paucity of movement on the right side persisted, and some speech delay and visual inattention were noted. Recent follow-up at 16.5 months of age demonstrated a right sided hemiplegia with increased tone and brisk reflexes. We describe the case in detail and review current knowledge regarding the management of arterial thrombosis in the neonate.

A neonatal thrombosis patient treated successfully with recombinant tissue plasminogen activator

Herein we report an asphyctic preterm neonate with respiratory distress and prothrombotic risk factors that responded positively to rtPA treatment following 2 attacks of acute thrombosis.

Conflict of interest:None declared.

Neonatal ascending aortic thrombus: successful medical treatment

Neonatal aortic thrombosis is a potentially life-threatening condition with significant morbidity and mortality if undiagnosed and untreated. The most common location of arterial thrombosis in neonates is in the abdominal aorta and is associated with umbilical artery catheterisation. There are only a few previous reports of thrombosis in the ascending aorta. We describe a case of ascending aortic thrombosis in a neonate who underwent successful thrombolytic therapy.

Low dose tissue plasminogen activator treatment for vascular thrombosis following cardiac catheterization in children: a single center experience

OBJECTIVES

To assess the efficacy and safety of low dose tissue plasminogen activator (tPA) therapy in children with vascular thrombosis following cardiac catheterization.

BACKGROUND

Currently, heparin is the standard of care for vascular thrombosis, however, it may not be efficacious in dissolving existing thrombi. Although tPA is an accepted thrombolytic therapy for life-threatening thrombosis in children, it is not a well-established treatment for the thrombosis of femoral vessels following cardiac catheterization.

METHODS

A retrospective analysis was performed from 1/1/2009 until 6/30/2011 at Rady Children's Hospital-San Diego (RCHSD) reviewing all cases with venous or arterial thrombosis at the vascular access site following cardiac catheterization, and a survey was conducted among the Congenital Cardiovascular Interventional Study Consortium members regarding their experience in tPA therapy.

RESULTS

At RCHSD, out of 1,155 catheterizations, 12 children developed femoral thrombosis. In three children, where 12-h heparin therapy was unsuccessful in resolving thrombosis, we used low-dose tPA according to the following regime: 0.05 mg/kg/h for 30 min, followed by 0.1 mg/kg/h for 4 h. We achieved thrombolysis in all cases evidenced by repeat ultrasound and return of palpable pulse with normal limb circulation. No complications were encountered. The survey confirmed that adult tPA dose (0.1-0.5 mg/kg/h) has 100% efficacy in resolving thrombi in children with vascular thrombosis, however, the rate of serious complications was not negligible (15%).

CONCLUSION

tPA is an efficacious therapy to dissolve thrombi that developed as a complication of cardiac catheterization in children. The rate of complications due to tPA may be reduced using a lower dose: 0.05-0.1 mg/kg/h.

Screening for coagulopathy and identification of children with acute lymphoblastic leukemia at a higher risk of symptomatic venous thrombosis: an AIEOP experience

INTRODUCTION

Venous thromboembolic events (VTEs) are frequent complications of childhood acute lymphoblastic leukemia (ALL) treatment. The aim of the study was to evaluate the rate of symptomatic VTEs in children with ALL and the predictive value of clinical and biological factors and routine monitoring of coagulation parameters in identifying children at a higher risk of this complication.

MATERIALS AND METHODS

Between September 2000 and July 2006, 2042 children (≥1 and younger than 18 y) with newly diagnosed ALL were enrolled in Italy in the AIEOP (Italian Association of Pediatric Hematology and Oncology)-BFM (Berlin-Frankfurt-Muenster) ALL 2000 trial. Patients with symptomatic VTEs (deep venous thromboses or cerebral venous thromboses) were identified after a careful review of clinical records. The impact of coagulation derangement at the onset of VTEs was evaluated by a nested case-control study.

RESULTS

Forty-eight (2.4%) children presented with a VTE. The rate of VTEs was higher in male patients (P=0.001); patients randomized to receive dexamethasone tended to have a higher rate of VTE compared with those who received prednisone (P=0.10). The coagulation derangement at the onset of VTE was not associated with VTE occurrence. The prevalence of a factor V Leiden G1691A mutation and the prothrombin G20210A variant was higher in children with VTE than that expected in the general population.

Current practice managements regarding thromboembolic prophylaxis within the pediatric sarcoma patient population

OBJECTIVE

Children with cancer are approximately 600 times more likely to develop thromboses than the general pediatric population. Current management strategies for children have been extrapolated from adult studies and prophylaxis guidelines remain controversial. The purpose of this study is to survey the current thromboembolic prophylaxis practice methods of physicians treating pediatric sarcoma patients.

METHODS

Physicians involved in the care of sarcoma patients were surveyed using a 5-question survey designed to evaluate current clinical practices.

RESULTS

Of 107 responding physicians, 67 identified themselves as involved in the treatment of pediatric sarcoma patients. The providers most likely to use any form of deep vein thrombosis prophylaxis were orthopedic surgeons (60%), followed by general surgeons (45%), pediatric oncologists (30%), and medical oncologists (25%). Of the providers polled, 48% use mechanical forms, 20% use chemical forms, and 31% use a combination.

CONCLUSIONS

Currently, there is a lack of consensus regarding thromboembolic prophylaxis for pediatric sarcoma patients.

The pediatric cardiology pharmacopeia: 2013 update

The use of medications plays a pivotal role in the management of children with heart diseases. Most children with increased pulmonary blood flow require chronic use of anticongestive heart failure medications until more definitive interventional or surgical procedures are performed. The use of such medications, particularly inotropic agents and diuretics, is even more amplified during the postoperative period. Currently, children are undergoing surgical intervention at an ever younger age with excellent results aided by advanced anesthetic and postoperative care. The most significant of these advanced measures includes invasive and noninvasive monitoring as well as a wide array of pharmacologic agents. This review update provides a medication guide for medical practitioners involved in care of children with heart diseases.

Retrospective evaluation of enoxaparin dosing in patients 48 weeks' postmenstrual age or younger in a neonatal intensive care unit

BACKGROUND

Enoxaparin is the anticoagulant of choice in neonates because of the ease of administration, predictable pharmacokinetics, and reduced adverse effects when compared to heparin. The Chest guidelines recommend that therapy in patients younger than 2 months should be initiated with enoxaparin 1.5 mg/kg administered subcutaneously twice daily. This starting dosage may be inadequate, leading to a delay in achieving therapeutic anti-factor Xa plasma concentrations.

OBJECTIVE

To determine an enoxaparin dose for neonatal patients that achieves a therapeutic anti-factor Xa plasma concentration and compare that dose to the recommended enoxaparin dose per published guidelines for this patient population.

METHODS

The study was designed as a single-center chart review. Eligible patients were identified by pharmacy anticoagulation records or a search of the electronic medical record for enoxaparin orders. Patients must have received enoxaparin subcutaneously twice daily and have had a postmenstrual age of 48 weeks or younger. Patients diagnosed with renal failure and those receiving prophylactic doses of enoxaparin were excluded.

RESULTS

The mean (SD) initial dose of enoxaparin was 1.4 (0.3) mg/kg subcutaneously twice daily, resulting in 27 of 33 patients (81.8%) having a subtherapeutic anti-factor Xa concentration. A mean enoxaparin dose of 2.0 (0.5) mg/kg was required to achieve a therapeutic anti-factor Xa plasma concentration (p < 0.001). Patients born prematurely required a higher enoxaparin dose (2.2 [0.5] mg/kg) than did those born at full-term gestation (1.8 [0.4] mg/kg; p < 0.05).

CONCLUSIONS

For patients 48 weeks' postmenstrual age or younger who are treated in a neonatal intensive care unit, a higher initial dose of enoxaparin than that suggested by the Chest guidelines is required to attain a therapeutic antifactor Xa plasma concentration. Premature neonates require a larger starting dose of enoxaparin than do infants born at full-term gestation.

Paediatric acute basilar thrombosis successfully treated with intravenous alteplase

Acute ischaemic stroke has significant attendant morbidity and is one of the top ten causes of childhood death. It requires prompt investigation and management, however little is known about the safety and efficacy of acute thrombolytic therapies in childhood arterial ischaemic stroke. The authors report a case of a 13-year-old girl with an acute basilar thrombosis, successfully treated with intravenous recombinant tissue plasminogen activator and discuss the management of paediatric arterial ischaemic stroke.