Coagulation and Bleeding Management in Pediatric Extracorporeal Membrane Oxygenation: Clinical Scenarios and Review

Antifibrinolytic and Adjunct Hemostatic Agents: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic-review informed, modified Delphi consensus regarding antifibrinolytic and adjunct hemostatic agents in neonates and children supported with extracorporeal membrane oxygenation (ECMO) for the Pediatric ECMO Anticoagulation CollaborativE consensus conference.

DATA SOURCES

A structured literature search was performed using PubMed, EMBASE, and Cochrane Library (CENTRAL) databases from January 1988 to May 2021.

STUDY SELECTION

Use of antifibrinolytics (epsilon-aminocaproic acid [EACA] or tranexamic acid), recombinant factor VII activated (rFVIIa), or topical hemostatic agents (THAs).

DATA EXTRACTION

Two authors reviewed all citations independently, with a third independent reviewer resolving conflicts. Eleven references were used for data extraction and informed recommendations. Evidence tables were constructed using a standardized data extraction form.

MEASUREMENTS AND MAIN RESULTS

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. Forty-eight experts met over 2 years to develop evidence-based recommendations and, when evidence was lacking, expert-based consensus statements for the management of bleeding and thrombotic complications in pediatric ECMO patients. 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. One weak recommendation and three consensus statements are presented.

CONCLUSIONS

Evidence supporting recommendations for administration of antifibrinolytics (EACA or tranexamic acid), rFVIIa, and THAs were sparse and inconclusive. Much work remains to determine effective and safe usage strategies.

Optimizing Outcomes in Extracorporeal Membrane Oxygenation Postcardiotomy in Pediatric Population

Extracorporeal membrane oxygenation (ECMO) is a rapidly emerging advanced life support technique used in cardiorespiratory failure refractory to other treatments. There has been an influx in the number of studies relating to ECMO in recent years, as the technique becomes more popular. However, there are still significant gaps in the literature including complications and their impacts and methods to predict their development. This review evaluates the available literature on the complications of ECMO postcardiotomy in the pediatric population. Areas explored include renal, cardiovascular, hematological, infection, neurological, and hepatic complications. Incidence, risk factors and potential predictors, and scoring systems for the development of these complications have been evaluated.

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.

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.

Blood transfusion is associated with increased mortality for neonates with congenital diaphragmatic hernia on extracorporeal membrane oxygenation support

BACKGROUND AND OBJECTIVES

Blood transfusion is frequently needed to maintain adequate haemostasis and improve oxygenation for patients treated with extracorporeal membrane oxygenation (ECMO). It is more so for neonates with immature coagulation systems who require surgical intervention such as congenital diaphragmatic hernia (CDH) repair. There is growing evidence suggesting an association between blood transfusions and increased mortality. The aim of this study is to evaluate the association of blood transfusions during the peri-operative period of CDH repair, among other clinical parameters, with mortality in neonates undergoing on-ECMO CDH repair.

MATERIALS AND METHODS

We performed a single centre retrospective chart review of all neonates with CDH undergoing on-ECMO surgical repair from January 2010 to December 2020. Logistic regression was used to investigate associations with survival status.

RESULTS

Sixty-two patients met the inclusion criteria. Platelet transfusions (odds ratio [OR] 1.42, 95% confidence interval [CI]: 1.06-1.90) in the post-operative period and ECMO duration (OR 1.17, 95% CI: 1.05-1.30) were associated with increased mortality. Major bleeding complications had the strongest association with mortality (OR 10.98, 95% CI: 3.27-36.91). Gestational age, birth weight, Apgar scores, sex, blood type, right versus left CDH, venovenous versus venoarterial ECMO and duration of ECMO before CDH repair and circuit change after adjusting for ECMO duration were not significantly associated with survival.

CONCLUSION

Platelet transfusion in the post-operative period and major bleeding are associated with increased mortality in CDH neonates with surgical repair. The data suggest a need to develop robust plans for monitoring and preventing coagulation aberrancies during neonatal ECMO support.

Extracorporeal membrane oxygenation in children: An update of a single tertiary center 11-Year experience from Croatia

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO) is an important treatment option for organ support in respiratory insufficiency, cardiac failure, or as an advanced tool for cardiopulmonary resuscitation. Reports on pediatric ECMO use in our region are lacking.

METHODS

This study is a retrospective review of all pediatric cases that underwent a veno-arterial (VA) or veno-venous (VV) ECMO protocol between November 2009 and August 2020 at the Department of Pediatrics, University Hospital Center Zagreb, Croatia.

RESULTS

Fifty-two ECMO runs identified over the period; data were complete for 45 cases, of which 23 (51%) were female, and median age was 8 months. Thirty-eight (84%) patients were treated using the VA-and 7 (16%) using VV-ECMO. The overall survival rate was 51%. Circulatory failure was the most common indication for ECMO (N = 38, 84%), and in 17 patients ECMO was started after cardiopulmonary resuscitation (E-CPR). Among survivors, 74% had no or minor neurological sequelae. Variables associated with poor outcome were renal failure with renal replacement therapy (p < .001) and intracranial injury (p < .001).

CONCLUSION

Overall survival rate in our cohort is comparable to the data published in the literature. The use of hemodialysis was shown to be associated with higher mortality. High rates of full neurological recovery among survivors are a strong case for further ECMO program development in our institution.

The Relative Early Decrease in Platelet Count Is Associated With Mortality in Post-cardiotomy Patients Undergoing Venoarterial Extracorporeal Membrane Oxygenation

Background: The relationship between the magnitude of platelet count decrease and mortality in post-cardiotomy cardiogenic shock (PCS) patients undergoing venoarterial extracorporeal membrane oxygenation (VA-ECMO) has not been well-reported. This study was designed to evaluate the association between the relative decrease in platelet count (RelΔplatelet) at day 1 from VA-ECMO initiation and in-hospital mortality in PCS patients.

Methods: Patients (n = 178) who received VA-ECMO for refractory PCS between January 2016 and December 2018 at the Beijing Anzhen Hospital were reviewed retrospectively. Multivariable logistic regression analyses were performed to assess the association between RelΔplatelet and in-hospital mortality.

Results: One hundred and sixteen patients (65%) were weaned from VA-ECMO, and 84 patients (47%) survived to hospital discharge. The median [interquartile range (IQR)] time on VA-ECMO support was 5 (3–6) days. The median (IQR) RelΔ platelet was 41% (26–59%). Patients with a RelΔ platelet ≥ 50% had an increased mortality compared to those with a RelΔ platelet < 50% (57 vs. 37%; p < 0.001). A large RelΔplatelet (≥50%) was independently associated with in-hospital mortality after controlling for potential confounders (OR 8.93; 95% CI 4.22–18.89; p < 0.001). The area under the receiver operating characteristic curve for RelΔ platelet was 0.78 (95% CI, 0.71–0.85), which was better than that of platelet count at day 1 (0.69; 95% CI, 0.61–0.77).

Conclusions: In patients receiving VA-ECMO for post-cardiotomy cardiogenic shock, a large relative decrease in platelet count in the first day after ECMO initiation is independently associated with an increased in-hospital mortality.

Analysis of Viscoelastic Testing in Pediatric Patients Using the Pediatric Extracorporeal Membrane Oxygenation Outcomes Registry

Use of viscoelastic tests (VETs), including thromboelastography (TEG) and rotational thromboelastometry (ROTEM), is increasing in the management of anticoagulation in extracorporeal membrane oxygenation (ECMO) patients. A retrospective review of data on 265 pediatric (<20 years old) ECMO patients who underwent VET and were submitted to the Pediatric ECMO Outcomes Registry (PEDECOR) was conducted to describe common coagulopathies in patients who underwent VET; associations between the VET parameters and traditional tests of coagulation; and comparisons in blood product usage in patients who underwent VET with those who did not. We calculated patient-level summary statistics and assessed differences between the groups using χ2 tests (categorical variables) and Kruskal-Wallis and Wilcoxon rank-sum tests (continuous variables). Viscoelastic test was utilized in 77% of patients in the analysis. Platelet dysfunction was the most common abnormality identified by TEG (30.8%) and ROTEM (9.7%). Bleeding patients who had VET performed received more cryoprecipitate transfusions than those who did not have VET (VET median = 9.7 ml/kg; interquartile range (IQR) = 4.3-22.0 ml/kg vs. no VET median = 5.1 ml/kg; IQR = 0-10.4 ml/kg; p = 0.0013). Given the growing use of VET in pediatric ECMO patients, further studies evaluating VET in managing complications as well as aiding in titration of anticoagulation therapy are needed.

Bivalirudin May Reduce the Need for Red Blood Cell Transfusion in Pediatric Cardiac Patients on Extracorporeal Membrane Oxygenation

We retrospectively compared anticoagulation with heparin and bivalirudin for 32 consecutive children under 18 years old during extracorporeal membrane oxygenation (ECMO) in our pediatric cardiac intensive care unit (PCICU). Between September 2015 and January 2018, 14 patients received heparin, 13 venoarterial (VA), and 1 venovenous (VV). From February 2018 to September 2019, 18 received bivalirudin (all VA). The mean (standard deviation [SD]) percentage of time with therapeutic activated partial thromboplastin time and activated clotting time was bivalirudin 54 (14%) and heparin 57 (11%), p = 0.4647, and percentage of time supratherapeutic was bivalirudin 18 (10%) and heparin 27 (12%), p = 0.0238. Phlebotomy-associated blood loss per hour of ECMO was double in the heparin compared with bivalirudin group 1.08 ml/h (0.20 ml/h), compared with 0.51 ml/h (0.07 ml/h), p = 0.0003, as well as interventions to control bleeding. Packed red blood cell (PRBC) transfusions significantly correlated with higher blood loss in the heparin group (Pearson correlation coefficient = 0.49, p = 0.0047). Overall amount of blood product utilization was not different between the groups. Survival to ECMO decannulation was 89% for bivalirudin and 57% for heparin, p = 0.0396, although 6 month survival was not significantly different (67% versus 57%, p = 0.5809). Heparin may increase the need for PRBC transfusions and strategies to attenuate bleeding when compared with bivalirudin for children receiving ECMO in PCICU.

Conversion From Activated Clotting Time to Anti-Xa Heparin Activity Assay for Heparin Monitoring During Extracorporeal Membrane Oxygenation

OBJECTIVES

Anticoagulation with unfractionated heparin remains the most common therapy used to prevent circuit thrombosis during extracorporeal membrane oxygenation, but no consensus exists on the optimal method or targets for heparin monitoring. From 2015 to 2018, we switched from monitoring heparin during extracorporeal membrane oxygenation using activated clotting times to anti-Xa heparin activity assays. This study describes the transition from activated clotting time to anti-Xa heparin activity assay monitoring and the associated clinical changes.

DESIGN

Retrospective analysis at single institution.

SETTING

Referral Children's Hospital.

PATIENTS

A total of 145 pediatric patients over 152 extracorporeal membrane oxygenation runs using 206 extracorporeal membrane oxygenation circuits.

INTERVENTIONS

Anticoagulation protocol quality improvement.

MEASUREMENTS AND MAIN RESULTS

From 2015 to 2018, heparin monitoring during extracorporeal membrane oxygenation changed from hourly activated clotting time to anti-Xa heparin activity assay every 6 hours with an associated 75% reduction in the circuit changes per extracorporeal membrane oxygenation day. Over the 4 years, patients with an average anti-Xa heparin activity assay of at least 0.25 U/mL showed a 59% reduction in circuit changes per extracorporeal membrane oxygenation day compared with less than 0.15 U/mL. In addition to its association with reduced circuit changes, anti-Xa heparin activity assay monitoring was also associated with reduced heparin dose changes per day from 11 ± 4 to 2 ± 1 (p < 0.001), smaller heparin dose changes (less variation in dose), and reduced diagnostic phlebotomy volumes from 41 ± 6 to 25 ± 11 mL/day (p < 0.001). The number of patients with reported bleeding decreased from 69% using activated clotting time to 51% (p = 0.03). Transfusion rates did not change.

CONCLUSIONS

Over 4 years, we replaced the activated clotting time assay with the anti-Xa heparin activity assay for heparin monitoring during extracorporeal membrane oxygenation. Minimum anti-Xa heparin activity assay levels of 0.25 U/mL were associated with reduced circuit changes. Further studies are needed to determine the optimum anti-Xa heparin activity assay therapeutic range during extracorporeal membrane oxygenation.

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

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

The use of therapeutic plasma exchange for pediatric patients supported on extracorporeal membranous oxygenator therapy: A narrative review

Therapeutic plasma exchange in children is increasingly recognized as a life-saving treatment and is challenged by some technical considerations. As extracorporeal membrane oxygenation has been used for nearly half a century for refractory reversible respiratory and/or cardiac failure in both pediatric and adult populations, it may serve as an extracorporeal platform for therapeutic plasma exchange. It is most commonly described in patients with sepsis with multiple organ failure or thrombocytopenia associated multi organ failure. Additional pathophysiological processes of inflammatory and immunological storms might benefit from the combination of extracorporeal membrane oxygenation and plasma exchange. This is a nonmethodological review of English-language reports of therapeutic plasma exchange performed in patients supported by extracorporeal membrane oxygenation, both pediatric and adult, searching six databases, MEDLINE, Clinical Key, GOOGLE SCHOLAR, CINAHL, Cochrane library, and EMBASE.

Antithrombin use during pediatric cardiac extracorporeal membrane oxygenation admission: insights from a national database

INTRODUCTION

The frequency of extracorporeal membrane oxygenation in pediatric patients continues to increase, especially in patients with complex congenital heart disease. Providing adequate anticoagulation is necessary for patients on extracorporeal membrane oxygenation and is achieved with adequate heparin administration. Antithrombin is administered to potentiate heparin's effects. However, the efficacy of antithrombin supplementation is unclear and a clear clinical benefit has not been established. We present a large retrospective study examining the effects of antithrombin on pediatric patients receiving extracorporeal membrane oxygenation.

METHODS

Data for this study were obtained from the Pediatric Health Information System and Pediatric Health Information System+ databases from 2004 to 2015. Pediatric patients receiving extracorporeal membrane oxygenation with a congenital heart disease diagnosis were included and divided into groups that did or did not utilize antithrombin. For all admissions, the following were captured: age of admission, gender, year of admission, length of stay, billed charges, inpatient mortality, the presence of specific congenital malformations of the heart, specific cardiac surgeries, and comorbidities.

RESULTS

A total of 9,193 admissions were included and 865 (9.4%) utilized antithrombin. Between groups, there were significantly different frequencies of co-morbidities, cardiac lesion types and antithrombin usage over the study period. There were significantly lower odds in the antithrombin group of venous thrombosis. Antithrombin was not significantly associated with hemorrhage; however, antithrombin was associated with increased inpatient mortality and a decrease in length of stay and billed charges.

CONCLUSION

Antithrombin administration is associated with increased mortality, a shorter length of stay, and decreased billing cost. Recently, antithrombin usage has been decreasing-potentially due to the reported lack of clinical benefit. Together, these results reinforce that antithrombin may not be indicated for all pediatric extracorporeal membrane oxygenation patients.