Heparin-induced thrombocytopenia in a pediatric patient receiving extracorporeal support and treated with argatroban

Anticoagulation with Intravenous Direct Thrombin Inhibitors in Pediatric Extracorporeal Membrane Oxygenation: A Systematic Review of the Literature

Although intravenous (IV) direct thrombin inhibitors (DTI) have gained interest in pediatric extracorporeal membrane oxygenation (ECMO), dosing and safety information is limited. The objective of this systematic review was to characterize DTI types, dosing, monitoring, and outcomes (bleeding and thromboembolic) in pediatric ECMO patients managed with IV DTIs. We conducted searches of MEDLINE (Ovid) and Embase (Elsevier) from inception through December 2022. Case reports, retrospective studies, and prospective studies providing per-patients or summary data for patient(s) <18 years of age receiving IV DTI for ECMO anticoagulation were included. Study selection and data extraction were conducted independently by two reviewers. A total of 28 studies: 14 case reports, 13 retrospective studies, and 1 prospective study were included, totaling 329 patients. Bivalirudin was utilized in 318 (96.7%), argatroban in 9 (2.7%), and lepirudin in 2 (0.6%) patients. Infusion dosing included: bivalirudin 0.14 ± 0.37 mg/kg/h, argatroban 0.69 ± 0.73 µg/kg/min, lepirudin 0.14 ± 0.02 mg/kg/h. Laboratory monitoring tests utilized were the activated clotting time, activated partial thromboplastin time (aPTT), diluted thrombin time, and thromboelastography measures. The aPTT was utilized in most patients (95%). Thromboembolism, bleeding, or death were observed in 17%, 17%, and 23% of bivalirudin, argatroban, and lepirudin patients, respectively. Bivalirudin appears to be the most frequently used DTI in pediatric ECMO. Dosing and laboratory monitoring varied, and bleeding and thromboembolic events were reported in 17% of patients. Prospective studies are warranted to establish dosing, monitoring, safety, and efficacy of bivalirudin and other IV DTI in pediatric ECMO.

Current and future strategies to monitor and manage coagulation in ECMO patients

Extracorporeal membrane oxygenation (ECMO) can provide life-saving support for critically ill patients suffering severe respiratory and/or cardiac failure. However, thrombosis and bleeding remain common and complex problems to manage. Key causes of thrombosis in ECMO patients include blood contact to pro-thrombotic and non-physiological surfaces, as well as high shearing forces in the pump and membrane oxygenator. On the other hand, adverse effects of anticoagulant, thrombocytopenia, platelet dysfunction, acquired von Willebrand syndrome, and hyperfibrinolysis are all established as causes of bleeding. Finding safe and effective anticoagulants that balance thrombosis and bleeding risk remains challenging. This review highlights commonly used anticoagulants in ECMO, including their mechanism of action, monitoring methods, strengths and limitations. It further elaborates on existing anticoagulant monitoring strategies, indicating their target range, benefits and drawbacks. Finally, it introduces several highly novel approaches to real-time anticoagulation monitoring methods including sound, optical, fluorescent, and electrical measurement as well as their working principles and future directions for research.

Anticoagulation in Neonatal ECMO: An Enigma Despite a Lot of Effort!

Extracorporeal membrane oxygenation (ECMO) is a valuable modality used to support neonates, children, and adults with cardiorespiratory failure refractory to conventional therapy. It requires use of anticoagulation to prevent clotting in the extracorporeal circuit. Balancing bleeding from excessive anticoagulation with thrombotic risk remains a difficult aspect of ECMO care. Despite many advances in ECMO technology, better understanding of the coagulation cascade and new monitoring schemes to adjust anticoagulation, bleeding and thrombosis remain the most frequent complications in ECMO and are associated with morbidity and mortality. In neonates, ECMO is also complicated by the immature hemostatic system, laboratory testing norms which are not specific for neonates, lack of uniformity in management, and paucity of high-quality evidence to determine best practices. Traditional anticoagulation focuses on the use of unfractionated heparin. Direct thrombin inhibitors are also used but have not been well-studied in the neonatal ECMO population. Anticoagulation monitoring is complex and currently available assays do not take into account thrombin generation or platelet contribution to clot formation. Global assays may add valuable information to guide therapy. This review provides an overview of hemostatic alterations, anticoagulation, monitoring and management, novel anticoagulant use, and circuit modifications for neonatal ECMO. Future considerations are also presented.

[Use of ECMO in adult patients with cardiogenic shock: a position paper of the Austrian Society of Cardiology]

The use of ECMO to stabilize critically ill patients with severely depressed cardiac function and hemodynamics increased in the last years due to broader availability, better performance and easier implantation of the devices. The present guidelines of the Austrian Society of Cardiology focus on the use of ECMO in adult non-operated patients with cardiac diseases. Not only indications and contraindications are highlighted, but also the equally important issues of monitoring, complication management, measures during implantation and operation, and weaning of the devices are treated in detail. Thereby the present guidelines aim to optimize the use of ECMO in the individual centers, and aim to help current non-ECMO centers in developing a local ECMO-program or to contact ECMO-centers for discussion of individual patients.

Trends in Parenteral Direct Thrombin Inhibitor Use in Pediatric Patients: Analysis of a Large Administrative Database

Context.—Parenteral direct thrombin inhibitors (DTIs) may be used in pediatric patients with contraindications to heparin therapy, such as heparin-induced thrombocytopenia. Few data exist regarding the use of DTIs in pediatric patients.

Objective.—To characterize the use of DTIs in pediatric patients, including monitoring strategies and bleeding complications.

Design.—A retrospective descriptive study was designed and the Pediatric Health Information System database was queried from 2004 to 2011 for pediatric patients receiving a parenteral DTI. Patient demographic and hospital data, mortality, disease state, and procedure information (from International Classification of Diseases, Ninth Revision codes) were collected from the query. DTI monitoring information was also collected. Patients were divided into 2 time periods (2004–2007, 2008–2011) to evaluate trends.

Results.—Two hundred eight patients met study criteria (50.9% male, 64.4% white), and children (2–12 years of age) represented 34.6% of the population. Congenital heart disease was present in 43.8% and cardiovascular surgical procedure occurred in 28.4%. Argatroban was most commonly used (73.1%) and bivalirudin use increased (P &lt; .001). Bleeding complications were present in 37.9% of patients and mortality was 19.7%. Bleeding complications were associated with lepirudin (62.5%) and argatroban (41.7%) more often as compared with bivalirudin (18.8%) (P &lt; .001). Activated partial thromboplastin time and prothrombin time were used more often in patients receiving argatroban and lepirudin in comparison with bivalirudin, and thrombin time was used more often in patients receiving lepirudin (P &lt; .001). Activated clotting time use increased over time (5.1% versus 17.5%, P = .02).

Conclusion.—Pediatric use of DTIs is infrequent and occurs in patients with high morbidity and mortality.

Challenges encountered with argatroban anticoagulation during cardiopulmonary bypass

Use of argatroban as an alternative to heparin during cardiopulmonary bypass (CPB) in patients with heparin-induced thrombocytopenia has gained some attention in the past two decades. Dosing of argatroban during CPB is complex due to lack of complete understanding of its pharmacokinetic profile and the various elements during CPB that may alter its plasma levels. We report a case where the challenges in dosing argatroban led to failure to provide adequate anticoagulation during CPB, as evidenced by clot formation in the oxygenator, and extensive bleeding in the postoperative period.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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