Antithrombin III administration in neonates with congenital diaphragmatic hernia during the first three days of extracorporeal membrane oxygenation

Recommendations on Monitoring and Replacement of Antithrombin, Fibrinogen, and Von Willebrand Factor in Pediatric Patients on Extracorporeal Membrane Oxygenation: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic review informed, modified Delphi consensus regarding monitoring and replacement of specific coagulation factors during pediatric extracorporeal membrane oxygenation (ECMO) support for the Pediatric ECMO Anticoagulation CollaborativE.

DATA SOURCES

A structured literature search was performed using PubMed, Embase, and Cochrane Library (CENTRAL) databases from January 1988 to May 2020, with an update in May 2021.

STUDY SELECTION

Included studies assessed monitoring and replacement of antithrombin, fibrinogen, and von Willebrand factor in pediatric ECMO support.

DATA EXTRACTION

Two authors reviewed all citations independently, with conflicts resolved by a third reviewer if required. Twenty-nine references were used for data extraction and informed recommendations. Evidence tables were constructed using a standardized data extraction form.

DATA SYNTHESIS

Risk of bias was assessed using the Quality in Prognosis Studies tool. The evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation system. A panel of 48 experts met over 2 years to develop evidence-based recommendations and, when evidence was lacking, expert-based consensus statements. A web-based modified Delphi process was used to build consensus via the Research And Development/University of California Appropriateness Method. Consensus was defined as greater than 80% agreement. We developed one weak recommendation and four expert consensus statements.

CONCLUSIONS

There is insufficient evidence to formulate recommendations on monitoring and replacement of antithrombin, fibrinogen, and von Willebrand factor in pediatric patients on ECMO. Optimal monitoring and parameters for replacement of key hemostasis parameters is largely unknown.

Antithrombin III supplementation during neonatal and pediatric extracorporeal membrane oxygenation

BACKGROUND

Bleeding and thrombosis are common extracorporeal membrane oxygenation (ECMO) complications associated with increased mortality. Heparin is the most commonly used ECMO anticoagulant, employed in 94% of cases. Reduced antithrombin III (AT3) levels could decrease heparin effectiveness. Neonates have inherently lower levels of AT3 than adults, and pediatric patients on ECMO can develop AT3 deficiency. One potential approach for patients on ECMO with AT3 deficiency is exogenous AT3 supplementation. However, there is conflicting data concerning the use of AT3 for pediatric and neonatal patients on ECMO.

METHODS

We analyzed the Bleeding and Thrombosis during ECMO database of 514 neonatal and pediatric patients on ECMO. We constructed daily regression models to determine the association between AT3 supplementation and rates of bleeding and thrombosis. Given the physiological differences between pediatric patients and neonates, we constructed separate models for each.

RESULTS

AT3 administration was associated with increased rates of daily bleeding among pediatric (adjusted odds ratio [aOR] 1.59, p < 0.01) and neonatal (aOR 1.37, p = 0.04) patients. AT3 supplementation did not reduce the rate of thrombosis for either pediatric or neonatal patients.

CONCLUSION

AT3 administration was associated with increased rates of daily bleeding, a hypothesized potential complication of AT3 supplementation. In addition, AT3 supplementation did not result in lower rates of thrombosis. We recommend clinicians utilize caution when considering supplementing patients on ECMO with exogenous AT3.

Anti-inflammatory effects of antenatal administration of stem cell derived extracellular vesicles in the brain of rat fetuses with congenital diaphragmatic hernia

PURPOSE

Congenital diaphragmatic hernia (CDH) survivors may experience neurodevelopmental impairment, whose etiology remains elusive. Preclinical evidence indicates that amniotic fluid stem cell extracellular vesicle (AFSC-EV) administration promotes lung development but their effects on other organs are unknown. Herein, we investigated the brain of rat fetuses with CDH for signs of inflammation and response to AFSC-EVs.

METHODS

CDH was induced by maternal nitrofen administration at E9.5. At E18.5, fetuses were injected intra-amniotically with saline or AFSC-EVs (isolated by ultracentrifugation, characterized as per MISEV guidelines). Fetuses from vehicle-gavaged dams served as controls. Groups were compared for: lung hypoplasia, TNFa and IL-1B brain expression, and activated microglia (Iba1) density in the subgranular zone (SGZ).

RESULTS

CDH lungs had fewer airspaces compared to controls, whereas AFSC-EV-treated lungs had rescued branching morphogenesis. Fluorescently labeled AFSC-EVs injected intra-amniotically into CDH fetuses had fluorescent signal in the brain. Compared to controls, the brain of CDH fetuses had higher TNFa and IL-1B levels, and increased activated microglia density. Conversely, the brain of AFSC-EV treated fetuses had inflammatory marker expression levels and microglia density similar to controls.

CONCLUSION

This study shows that the brain of rat fetuses with CDH has signs of inflammation that are abated by the intra-amniotic administration of AFSC-EVs.

Antithrombin III infusion improves anticoagulation in congenital diaphragmatic hernia patients on extracorporeal membrane oxygenation

PURPOSE

Achieving effective anticoagulation during neonatal extracorporeal membrane oxygenation (ECMO) without increasing the risk of hemorrhage remains challenging. The use of antithrombin III (AT-III) for this purpose has been examined, but studies have been limited to intermittent bolus dosing. We aimed to evaluate the efficacy and safety of an institutionally developed AT-III continuous infusion protocol in neonates receiving ECMO for the treatment of congenital diaphragmatic hernia (CDH).

METHODS

In this single center, retrospective study, all neonates with a CDH who received ECMO support during the study period were included. Data on anticoagulation labs and therapy, life-threatening bleeding, and circuit changes were analyzed.

RESULTS

Eleven patients were divided into two groups: patients with AT-III continuous infusion (n = 5) and without (n = 6). There were no differences in the gestational age (p = 0.29), sex (p = 1.00), ECMO duration (p = 0.59), or initial AT-III levels (p = 0.76) between groups. Patients in the AT-III infusion group had on average 18.5% higher AT-III levels (p < 0.0001). Patients receiving continuous AT-III infusions spent a significantly higher percentage of ECMO time within the therapeutic range, measured using anti-Factor Xa levels (64.9±4.2% vs. 29.1±8.57%, p = 0.008), and required fewer changes to the heparin infusion rate (6.48±0.88 vs 2.38±0.36 changes/day changes/day, p = 0.005). Multivariate analysis revealed continuous infusion of AT-III did not increase the rate of intracranial or surgical bleeding (p = 0.27).

CONCLUSION

AT-III as a continuous infusion in CDH neonates on ECMO provides a decreased need to modify heparin infusion and more consistent therapeutic anticoagulation without increasing the risk of life-threatening bleeding.

Evaluation of acquired antithrombin deficiency in paediatric patients supported on extracorporeal membrane oxygenation

AIMS

There remains a paucity of literature regarding best practice for antithrombin (AT) monitoring, dosing and dose-response in paediatric extracorporeal membrane oxygenation (ECMO) patients.

METHODS

We conducted a retrospective cohort study at a quaternary care paediatric intensive care unit in all patients <18 years of age supported on ECMO from 1 June 2011 to 30 April 2020. Adverse events and outcomes were characterized for all ECMO runs. AT activity and replacement were characterized and compared between two clinical protocols. AT activities measured post- vs. pre-AT replacement were compared in order to characterize a dose-response relationship.

RESULTS

The final cohort included 191 patients with 201 ECMO runs and 2028 AT activity measurements. The median AT activity was 65% (interquartile range [IQR], 51-82) and 879 (43.3%) measurements met the criteria of deficient. The overall median AT dose and increase in AT activity were 50.6 units/kg/dose (IQR, 39.5-67.2) and 23.5% (IQR, 9.8-36.0), respectively. In the protocol that restricted AT activity measurements to clinical scenarios concerning for heparin resistance, there was significantly higher dosing in conjunction with significantly fewer overall administrations. Approximately one third of AT activity remained deficient after repletion. There was no difference in mechanical complications, reasons for discontinuation of ECMO support, time on ECMO or survival between protocols.

CONCLUSIONS

There was a high prevalence of AT deficiency in paediatric ECMO patients. An AT replacement protocol based on evaluating heparin resistance is associated with fewer AT administrations, with similar circuit and patient outcomes. Further data are needed to identify optimal dosing strategies.

Hemostasis in neonatal ECMO

Extracorporeal membrane oxygenation (ECMO) is a life-saving support for cardio-respiratory function. Over the last 50 years, the extracorporeal field has faced huge technological progress. However, despite the improvements in technique and materials, coagulation problems are still the main contributor to morbidity and mortality of ECMO patients. Indeed, the incidence and survival rates of the main hemorrhagic and thrombotic complications in neonatal respiratory ECMO are relevant. The main culprit is related to the intrinsic nature of ECMO: the contact phase activation. The exposure of the human blood to the non-endothelial surface triggers a systemic inflammatory response syndrome, which chronically activates the thrombin generation and ultimately leads to coagulative derangements. Pre-existing illness-related hemostatic dysfunction and the peculiarity of the neonatal clotting balance further complicate the picture. Systemic anticoagulation is the management's mainstay, aiming to prevent thrombosis within the circuit and bleeding complications in the patient. Although other agents (i.e., direct thrombin inhibitors) have been recently introduced, unfractionated heparin (UFH) is the standard of care worldwide. Currently, there are multiple tests exploring ECMO-induced coagulopathy. A combination of the parameters mentioned above and the evaluation of the patient's underlying clinical context should be used to provide a goal-directed antithrombotic strategy. However, the ideal algorithm for monitoring anticoagulation is currently unknown, resulting in a large inter-institutional diagnostic variability. In this review, we face the features of the available monitoring tests and approaches, mainly focusing on the role of point-of-care (POC) viscoelastic assays in neonatal ECMO. Current gaps in knowledge and areas that warrant further study will also be addressed.

Plasma and Platelet Transfusions Strategies in Neonates and Children Undergoing Cardiac Surgery With Cardiopulmonary Bypass or Neonates and Children Supported by Extracorporeal Membrane Oxygenation: From the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding

OBJECTIVES

To present the recommendations and consensus statements with supporting literature for plasma and platelet transfusions in critically ill neonates and children undergoing cardiac surgery with cardiopulmonary bypass or supported by extracorporeal membrane oxygenation from the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding.

DESIGN

Systematic review and consensus conference of international, multidisciplinary experts in platelet and plasma transfusion management of critically ill children.

SETTING

Not applicable.

PATIENTS

Critically ill neonates and children following cardiopulmonary bypass or supported by extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A panel of nine experts developed evidence-based and, when evidence was insufficient, expert-based statements for plasma and platelet transfusions in critically ill neonates and children following cardiopulmonary bypass or supported by extracorporeal membrane oxygenation. These statements were reviewed and ratified by the 29 Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding experts. A systematic review was conducted using MEDLINE, EMBASE, and Cochrane Library databases, from inception to December 2020. Consensus was obtained using the Research and Development/University of California, Los Angeles Appropriateness Method. Results were summarized using the Grading of Recommendations Assessment, Development, and Evaluation method. We developed one good practice statement, two recommendations, and three expert consensus statements.

CONCLUSIONS

Whereas viscoelastic testing and transfusion algorithms may be considered, in general, evidence informing indications for plasma and platelet transfusions in neonatal and pediatric patients undergoing cardiac surgery with cardiopulmonary bypass or those requiring extracorporeal membrane oxygenation support is lacking.

Antithrombin Dose Optimization in Extracorporeal Membrane Oxygenation in Infants

Anticoagulation in extracorporeal membrane oxygenation (ECMO) is challenging, with significant morbidity and mortality associated with thrombotic complications. Unfractionated heparin (UFH) is commonly used, which depends on native antithrombin (AT) function to exert anticoagulant effects. Antithrombin deficiency is common in infants on ECMO and replacement with AT concentrate may be warranted. However, dosing recommendations in this population are limited. We conducted a retrospective review of patients <1 year of age who received recombinant AT (ATryn) while on UFH and ECMO between January 1, 2010 and December 31, 2017. Commonly used dosing equations were assessed to determine their ability to predict postdose AT levels. Patient AT levels were compared with equation-predicted postdose AT levels to determine a correlation. A total of 102 doses in 41 patients were used for analysis. Baseline mean AT level was 43% (±13%) and mean AT doses were 134 units (±58.1 units) or 40.5 units/kg (±18.7 units/kg). Median increase in the AT level was 8% (interquartile range 2-17%) with a mean postdose level of 52.6% (±14.2%). Weight-based dosing poorly correlated with postdose AT levels (r2 = 0.082). Postdose levels were best predicted when using an equation that included desired change in the AT level from baseline, the patient's weight, and added weight from the volume of the ECMO circuit (r2 = 0.427). Prospective studies are needed to evaluate optimal dosing strategies, safety, and efficacy of AT in this population.

Anticoagulation and Transfusion Management During Neonatal and Pediatric Extracorporeal Membrane Oxygenation: A Survey of Medical Directors in the United States

OBJECTIVES

To compare current practices within the United States of anticoagulation management and blood transfusion in neonatal and pediatric extracorporeal membrane oxygenation patients with a 2013 international report.

DESIGN

Cross-sectional survey distributed between August and December 2019.

SETTING

Extracorporeal Life Support Organization-registered neonatal and pediatric extracorporeal membrane oxygenation centers in the United States.

PARTICIPANTS

Extracorporeal membrane oxygenation medical directors.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Eighty-three medical directors at 108 centers responded. After removing four duplicate responses, 79 surveys were analyzed. Seventy-nine percent (n = 62) report a written extracorporeal membrane oxygenation protocol for both anticoagulation and blood product management. Ninety-four percent (n = 74) report unfractionated heparin as their primary anticoagulant; the remaining use the direct thrombin inhibitor, bivalirudin. Ninety percent (n = 71) report measuring antifactor Xa levels. Most centers report using a combination of assays to monitor heparin therapy, either antifactor Xa and activated partial thromboplastin time (54%) or more commonly antifactor Xa and activated clotting time (68%). Forty-one percent use viscoelastic tests to aid management. Goal monitoring levels and interventions generated by out of range values are variable. Fifty-one percent will replace antithrombin. Platelet transfusion thresholds vary by age and center with ranges from 50,000 to 100,000 cells/µL. Eighty-two percent of respondents are willing to participate in a randomized controlled trial comparing anticoagulation strategies for patients receiving extracorporeal membrane oxygenation.

CONCLUSIONS

Compared with the 2013 pediatric population, extracorporeal membrane oxygenation center anticoagulation and blood transfusion approaches continue to vary widely. Most report continued use of heparin as their primary anticoagulant and follow a combination of monitoring assays with the majority using the antifactor Xa assay in their practices, a significant shift from prior results. Antithrombin activity levels and viscoelastic tests are followed by a growing number of centers. Platelet transfusion thresholds continue to vary widely. Future research is needed to establish optimal anticoagulation and blood transfusion management.

Neonatal respiratory and cardiac ECMO in Europe

Neonatal extracorporeal membrane oxygenation (ECMO) is a life-saving procedure for critically ill neonates suffering from a potentially reversible disease, causing severe cardiac and/or respiratory failure and refractory to maximal conventional management. Since the 1970s, technology, management, and clinical applications of neonatal ECMO have changed. Pulmonary diseases still represent the principal neonatal diagnosis, with an overall 74% survival rate, and up to one-third of cases are due to congenital diaphragmatic hernia. The overall survival rate in cardiac ECMO is lower, with congenital heart defect representing the main indication. This review provides an overview of the available evidence in the field of neonatal ECMO. We will address the changing epidemiology, basic principles, technologic advances in circuitry, and monitoring, and deliver a current multidisciplinary management framework, focusing on ECMO applications, complications, and long-term morbidities. Lastly, areas for further research will be highlighted.Conclusions: ECMO is a life support with a potential impact on long-term patients' outcomes. In the next years, advances in knowledge, technology, and expertise may push neonatal ECMO boundaries towards more premature and increasingly complex infants, with the final aim to reduce the burden of ECMO-related complications and improve overall patients' outcomes. What is Known: • ECMO is a life-saving option in newborns with refractory respiratory and/or cardiac failure. • The multidisciplinary ECMO management is challenging and may expose neonates to complications with an impact on long-term outcomes. What is New: • Advances in technology and biomaterials will improve neonatal ECMO management and, eventually, the long-term outcome of these complex patients. • Experimental models of artificial placenta and womb technology are under investigation and may provide clinical translation and future research opportunities.

Updates in Pediatric Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation is an increasingly used mode of life support for patients with cardiac and/or respiratory failure refractory to conventional therapy. This review provides a synopsis of the evolution of extracorporeal life support in neonates, infants, and children and offers a framework for areas in need of research. Specific aspects addressed are the changing epidemiology; technologic advancements in extracorporeal membrane oxygenation circuitry; the current status and future direction of anticoagulation management; sedative and analgesic strategies; and outcomes, with special attention to the lessons learned from neonatal survivors.

Antithrombin supplementation during extracorporeal membrane oxygenation: study protocol for a pilot randomized clinical trial

BACKGROUND

Normal levels of plasma antithrombin (AT) activity might decrease heparin requirements to achieve an adequate level of anticoagulation during treatment with extracorporeal membrane oxygenation (ECMO). Acquired AT deficiency during ECMO is common, but formal recommendations on target, timing, and rate of AT supplementation are lacking. Thus, we conceived a pilot trial to evaluate the feasibility and safety of prolonged AT supplementation in patients requiring veno-venous ECMO for respiratory failure.

METHODS

Grifols Antithrombin Research Awards (GATRA) is a prospective, randomized, single blinded, multicenter, controlled two-arm trial. Patients undergoing veno-venous ECMO will be randomized to either receive AT supplementation to maintain a functional AT level between 80 and 120% (AT supplementation group) or not (control group) for the entire ECMO course. In both study groups, anticoagulation will be provided with unfractionated heparin following a standardized protocol. The primary endpoint will be the dose of heparin required to maintain the ratio of activated partial thromboplastin time between 1.5 and 2. Secondary endpoints will be the adequacy of anticoagulation and the incidence of hemorrhagic and thrombotic complications.

DISCUSSION

GATRA is a pilot trial that will test the efficacy of a protocol of AT supplementation in decreasing the heparin dose and improving anticoagulation adequacy during ECMO. If positive, it might provide the basis for a future larger trial aimed at verifying the impact of AT supplementation on a composite outcome endpoint including hemorrhagic events, transfusion requirements, and mortality.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03208270 . Registered on 5 July 2017.

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.

Thromboprophylaxis in Extracorporeal Circuits: Current Pharmacological Strategies and Future Directions

The development of extracorporeal devices for organ support has been a part of medical history and progression since the late 1900s. These types of technology are primarily used and developed in the field of critical care medicine. Unfractionated heparin, discovered in 1916, has really been the only consistent form of thromboprophylaxis for attenuating or even preventing the blood-biomaterial reaction that occurs when such technologies are initiated. The advent of regional anticoagulation for procedures such as continuous renal replacement therapy and plasmapheresis have certainly removed the risks of systemic heparinization and heparin effect, but the challenges of the blood-biomaterial reaction and downstream effects remain. In addition, regional anticoagulation cannot realistically be applied in a system such as extracorporeal membrane oxygenation because of the high blood flow rates needed to support the patient. More recently, advances in the technology itself have resulted in smaller, more compact extracorporeal life support (ECLS) systems that can-at certain times and in certain patients-run without any form of anticoagulation. However, the majority of patients on ECLS systems require some type of systemic anticoagulation; therefore, the risks of bleeding and thrombosis persist, the most devastating of which is intracranial hemorrhage. We provide a concise overview of the primary and alternate agents and monitoring used for thromboprophylaxis during use of ECLS. In addition, we explore the potential for further biomaterial and technologic developments and what they could provide when applied in the clinical arena.

The Impact of Antithrombin III Use in Achieving Anticoagulant Goals in Pediatric Patients

OBJECTIVES

To determine the percentage of patients with >10% reduction in heparin infusion rate within 48 hours of antithrombin III (ATIII) administration. Secondary objectives include the achievement of therapeutic anticoagulation and determining the days of subtherapeutic infusion prior to supplementation.

METHODS

Retrospective chart review of 12 patients younger than 18 years of age who received ATIII concentrate supplementation while on continuous heparin infusion. Specific indications for heparin infusion therapy included extracorporeal membrane oxygenation (ECMO), treatment of thrombus, and post implantation of ventricular assist device(s).

RESULTS

From time of heparin initiation to ATIII supplementation, patients spent a mean 4.9 ± 2.6 days of subtherapeutic infusion and required uptitration from a mean of 15.3 ± 4.4 units/kg/hr to a mean rate of 40.7 ± 9.5 units/kg/hr. 58.3% of the patients (n = 7) had a ≥10% reduction from the baseline heparin infusion rate within 48 hours of ATIII administration. Those patients considered responders (≥10% reduction from baseline rate) had a slightly higher mean baseline antithrombin level (76.3% ± 22.0% vs. 58.6% ± 2.7% in non-responders, p = 0.1) and were administered comparable doses of ATIII. ATIII supplementation did appear to increase the time of therapeutic anticoagulation within the 48 hours.

CONCLUSIONS

Administration of ATIII is associated with >10% decrease in heparin requirements in more than half of the patients identified. In those patients deemed non-responders, there was a trend towards lower baseline antithrombin serum levels. Further studies are warranted to determine if the lack of response in some patients is due to inadequate dosing of ATIII or any patient-related factors.

Continuous Antithrombin III Administration in Pediatric Veno-Arterial Extracorporeal Membrane Oxygenation

The purpose of this retrospective case-control study is to determine the effect of continuous antithrombin III (ATIII) infusion on extracorporeal membrane oxygenation (ECMO) coagulation. All ECMO patients within the pediatric intensive care unit from January 2012 to July 2014 were included. Comparison was made between those who received continuous infusion ATIII through a standardized replacement protocol with historic controls receiving intermittent ATIII doses. Patients receiving the continuous infusion ATIII protocol spent more time in goal ACT range (71.9% vs 52.2%, p < 0.0001). Mean daily ATIII activity was also increased in study group (77.3% versus 68.6%, p = 0.04). No statistical differences in number of heparin dose changes per day (3 versus 3.22, p = 0.90) were present between the 2 groups. Only 28% of the historic controls receiving intermittent ATIII doses achieved normal ATIII activity as compared with 80% of study patients (p = 0.24). Maximum heparin dose was also lower in continuous infusion protocol group (p < 0.01). Compared with nonprotocolized intermittent dosing, the use of a continuous infusion ATIII protocol demonstrated increased time within goal ACT range at a lower heparin dose, no increase in hemostatic complications, and trends toward fewer heparin changes and lower blood product usage.

Extracorporeal Life Support: Four Decades and Counting

Extracorporeal membrane oxygenation (ECMO) or extracorporeal life support (ECLS) is a form of heart lung bypass that is used to support neonates, pediatrics, and adult patients with cardiorespiratory failure for days or weeks till organ recovery or transplantation. Venoarterial (VA) and venovenous (VV) ECLS are the most common modes of support. ECLS circuit components and monitoring have been evolving over the last 40 years. The technology is safer, simpler, and more durable with fewer complications. The use of neonatal respiratory ECLS use has been declining over the last two decades, while adult respiratory ECLS is growing especially since the H1N1 influenza pandemic in 2009. This review provides an overview of ECLS evolution over the last four decades, its use in neonatal, pediatric and adults, description of basic principles, circuit components, complications, and outcomes as well as a quick look into the future.

Outcomes following routine antithrombin III replacement during neonatal extracorporeal membrane oxygenation

BACKGROUND

We sought to examine the effect of routine antithrombin III (AT3) infusion on hemorrhagic and thrombotic complications, blood product utilization, and circuit lifespan in neonatal extracorporeal membrane oxygenation (ECMO).

METHODS

We performed a retrospective cohort study of 162 infants placed on ECMO for hypoxic respiratory failure. Infants requiring ECMO for primary cardiac support were excluded. Demographic data, time on ECMO, blood product usage, coagulation profile, and complications were compared between 90 control patients and 72 patients treated with AT3.

RESULTS

Infants receiving AT3 during ECMO had less thrombotic and similar bleeding complications as compared to infants receiving standard anticoagulation therapy. Total blood product infusion during ECMO was decreased (54.7±20.1 vs. 67.4±34.9mL/kg per day, p=0.001) in infants receiving AT3 during ECMO. Tighter control of activated clotting time and higher serum heparin anti-Xa levels were observed in the AT3 cohort during the first days of ECMO support. 1st ECMO circuit lifespan did not differ between groups.

CONCLUSIONS

Routine administration of AT3 in neonates receiving ECMO therapy was associated with tighter control of anticoagulation and a reduction in thrombotic events without increasing unwanted bleeding. However, circuit lifespan was unaffected.

LEVEL OF EVIDENCE

Level III.

Antithrombin Concentrate Use in Pediatric Extracorporeal Membrane Oxygenation: A Multicenter Cohort Study

OBJECTIVE

To describe antithrombin concentrate use and to compare thrombotic and hemorrhagic outcomes throughout the hospital stay in pediatric subjects who received extracorporeal membrane oxygenation in a Pediatric Health Information System-participating children's hospital.

DESIGN

Retrospective, multi-center, cohort study.

SETTING

Forty-three free-standing children's hospitals participating in Pediatric Health Information System.

SUBJECTS

Children older than or equal to 18 years of age who underwent extracorporeal membrane oxygenation between 2003 and 2012.

INTERVENTIONS

Subjects were classified as receiving antithrombin if they received at least one dose of antithrombin while on extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

International Classification of Diseases, Ninth Revision, Clinical Modification codes codes were used to identify hemorrhagic and thrombotic complications during their hospitalization. Pediatric Health Information System data were analyzed to determine hospital-length of stay and in-hospital mortality. A total of 1,931 of 8,601 eligible subjects (21.5%) received at least one dose of antithrombin during their extracorporeal membrane oxygenation course. Antithrombin use during extracorporeal membrane oxygenation increased from 2.4% to 51.9% (p < 0.001) over the 10-year study period. Subjects who received antithrombin while on extracorporeal membrane oxygenation were younger (p = 0.02), had more chronic conditions (p < 0.001), and longer hospital stays (p < 0.001). On multivariate analysis, antithrombin use was associated with thrombotic events (odds ratio, 1.55; 95% CI, 1.36-1.77; p < 0.001), hemorrhagic events (odds ratio, 1.27; 95% CI, 1.14-1.42; p < 0.001), and longer hospital length of stays (slope coefficient, 1.05 d; 95% CI, 1.04-1.06; p < 0.001). No difference was observed in mortality (odds ratio, 0.99; 95% CI, 0.89-1.11; p = 0.90).

CONCLUSIONS

In this multicenter retrospective cohort study, subjects who received antithrombin during extracorporeal membrane oxygenation had a higher number of thrombotic and hemorrhagic events throughout the hospitalization and longer length of stays without an associated difference in mortality. While limitations exist with this analysis and results should be interpreted with caution, the fact remains that over half of pediatric patients on extracorporeal membrane oxygenation are currently receiving antithrombin without clear benefit, with extra cost, and potential harms, there needs to be strong consideration for a clinical trial.

Use and Future Investigations of Recombinant and Plasma-Derived Coagulation and Anticoagulant Products in the Neonate

Although congenital bleeding disorders can manifest in the newborn period, the most common causes of bleeding and thrombosis in neonates are acquired conditions. Factor concentrates are used for specific diagnoses (hemophilia with inhibitors, specific factor deficiency, von Willebrand disease) and approved indications, and increasingly for off-label indications (bleeding in surgery cardiopulmonary bypass, extracorporeal membrane oxygenation). We will review the approved indications for factor products in the neonate and discuss the evidence and rationale for off-label use of factor products in management of bleeding and thrombosis in the neonate.

Bivalirudin as an Alternative to Heparin for Anticoagulation in Infants and Children

Bivalirudin, a direct thrombin inhibitor, is a useful alternative to heparin for anticoagulation in infants and children. It has been found to be effective in patients requiring treatment of thrombosis, as well as those needing anticoagulation during cardiopulmonary bypass, extracorporeal life support, or with a ventricular assist device. While it has traditionally been used in patients who were unresponsive to heparin or who developed heparin-induced thrombocytopenia, it has recently been studied as a first-line agent. Bivalirudin, unlike heparin, does not require antithrombin to be effective, and as a result, has the potential to provide a more consistent anticoagulation. The case reports and clinical studies currently available suggest that bivalirudin is as effective as heparin at reaching target activated clotting times or activated partial thromboplastin times, with equivalent or the lower rates of bleeding or thromboembolic complications. It is more expensive than heparin, but the cost may be offset by reductions in the costs associated with heparin use, including anti-factor Xa testing and the need for administration of antithrombin. The most significant disadvantage of bivalirudin remains the lack of larger prospective studies demonstrating its efficacy and safety in the pediatric population.

Thrombosis in the Neonatal Intensive Care Unit

Neonates have the highest risk for pathologic thrombosis among pediatric patients. A combination of genetic and acquired risk factors significantly contributes to this risk, with the most important risk factor being the use of central venous catheters. Proper imaging is critical for confirming the diagnosis. Despite a significant number of these events being life- and limb-threatening, there is limited evidence on what the appropriate management strategy should be. Evaluation and treatment of any neonate with a clinically significant thrombosis should occur at a tertiary referral center that has proper support.

Extracorporeal life support: updates and controversies

The use of Extracorporeal Life Support (ECLS) in children and adults has markedly increased during the past few years with over 4000 patients placed on ECLS every year in over 200 centers. This article focuses on updates to the physiology and mechanics of ECLS with use of magnetically levitated centrifugal pumps, hollow-fiber gas-exchange devices, and bi-caval dual-lumen catheters. We also explore controversies in management including indications, cannulation approaches, renal replacement, monitoring of anticoagulation, early ambulation, and termination of ECLS. Finally, we present changes in the systems that provide ECLS including the single-provider model and regionalization of care.