Factors Associated with Bleeding and Thrombosis in Children Receiving Extracorporeal Membrane Oxygenation

Quantifiable Bleeding in Children Supported by Extracorporeal Membrane Oxygenation and Outcome

OBJECTIVES

To evaluate the association between bleeding from chest tubes and clinical outcomes in children supported by extracorporeal membrane oxygenation.

DESIGN

Secondary analysis of a large observational cohort study.

SETTING

Eight pediatric institutions within the Eunice Kennedy Shriver National Institute of Child Health and Human Development's Collaborative Pediatric Critical Care Research Network.

PATIENTS

Critically ill children supported by extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Daily chest tube bleeding, results from hemostatic assays, transfusion volumes, 90-day PICU-free days, and mortality were collected prospectively by trained bedside extracorporeal membrane oxygenation specialists and research coordinators. Extracorporeal membrane oxygenation was employed in the care of 514 consecutive patients. Sixty percent of patients had at least one episode of chest tube bleeding (median chest tube blood volume over the entire extracorporeal membrane oxygenation course was 123 mL/kg [interquartile range, 47-319 mL/kg]). Twenty-six percent had at least 1 day of bleeding from the chest tube greater than 100 mL/kg/d. The number of days with chest tube bleeding greater than 60 mL/kg/d was independently associated with increased in-hospital mortality (adjusted odds ratio, 1.43; 95% CI, 1.05-1.97; p = 0.02) and decreased PICU-free days (beta coefficient, -4.2; 95% CI, -7.7 to -0.6; p = 0.02). The total amount of bleeding from chest tube were independently associated with increased mortality (per mL/kg/extracorporeal membrane oxygenation run; adjusted odds ratio, 1.002; 95% CI, 1.000-1.003; p = 0.04). Fibrinogen, weight, indication for extracorporeal membrane oxygenation, and need for hemodialysis were independently associated with chest tube bleeding, whereas platelet count, coagulation tests, heparin dose, and thrombotic events were not.

CONCLUSIONS

In children supported by extracorporeal membrane oxygenation, chest tube bleeding above 60 mL/kg/d was independently associated with worse clinical outcome. Low fibrinogen was independently associated with chest tube bleeding, whereas platelet count and hemostatic tests were not. Further research is needed to evaluate if interventions to prevent or stop chest tube bleeding influence the clinical outcome.

Hematologic concerns in extracorporeal membrane oxygenation

This ISTH "State of the Art" review aims to critically evaluate the hematologic considerations and complications in extracorporeal membrane oxygenation (ECMO). ECMO is experiencing a rapid increase in clinical use, but many questions remain unanswered. The existing literature does not address or explicitly state many pertinent details that may influence hematologic complications and, ultimately, patient outcomes. This review aims to broadly introduce modern ECMO practices, circuit designs, circuit materials, hematologic complications, transfusion-related considerations, age- and size-related differences, and considerations for choosing outcome measures. Relevant studies from the 2019 ISTH Congress in Melbourne, which further advanced our understanding of these processes, will also be highlighted.

Extracorporeal membrane oxygenation in pregnancy and the postpartum period: a systematic review of case reports

The use of extracorporeal membrane oxygenation (ECMO) as salvage therapy for patients with severe cardiopulmonary failure has increased significantly in the past decade. However, the use of ECMO in pregnant and peripartum patients has received scant attention. We performed a systematic review of case reports in the literature, documenting indications and outcomes of ECMO in pregnancy and postpartum patients. Case reports on ECMO use in pregnant and postpartum patients were retrieved from MEDLINE, EMBASE and SCOPUS databases up to December 2018. Ninety publications reporting on 97 patients met our inclusion criteria. The majority of publications reported peripartum or postpartum ECMO use for cardiovascular failure (60.8%), while the remainder had respiratory failure. Adult Respiratory Distress Syndrome (91.9%) was the most common respiratory indication while pulmonary embolism (23.7%) and peripartum cardiomyopathy (16.9%) accounted for the two most common cardiovascular indications. Hemorrhage was the most common complication of ECMO reported (31.9%). Of 96 documented neonatal outcomes, 80 neonates (83.3%) survived while 88 of 97 (90.7%) mothers survived. Extracorporeal membrane oxygenation appears to be a viable life support modality in pregnant and postpartum women with severe cardiopulmonary failure, but publication bias in our study cohort should be considered.

Evaluating Mortality Risk Adjustment Among Children Receiving Extracorporeal Support for Respiratory Failure

This study evaluates whether three commonly used pediatric intensive care unit (PICU) severity of illness scores, pediatric risk of mortality score (PRISM) III, pediatric index of mortality (PIM) 2, and pediatric logistic organ dysfunction (PELOD), are the appropriate tools to discriminate mortality risk in children receiving extracorporeal membrane oxygenation (ECMO) support for respiratory failure. This study also evaluates the ability of the Pediatric Risk Estimate Score for Children Using Extracorporeal Respiratory Support (Ped-RESCUERS) to discriminate mortality risk in the same population, and whether Ped-RESCUERS' discrimination of mortality is improved by additional clinical and laboratory measures of renal, hepatic, neurologic, and hematologic dysfunction. A multi-institutional retrospective cohort study was conducted on children aged 29 days to 17 years with respiratory failure requiring respiratory ECMO support. Discrimination of mortality was evaluated with the area under the receiver operating curve (AUC); model calibration was measured by the Hosmer-Lemeshow goodness of fit test and Brier score. Admission PRISM-III, PIM-2, and PELOD were found to have poor ability to discriminate mortality with an AUC of 0.56 [0.46-0.66], 0.53 [0.43-0.62], and 0.57 [0.47-0.67], respectively. Alternatively, Ped-RESCUERS performed better with an AUC of 0.68 [0.59-0.77]. Higher alanine aminotransferase, ratio of the arterial partial pressure of oxygen the fraction of inspired oxygen, and lactic acidosis were independently associated with mortality and, when added to Ped-RESCUERS, resulted in an AUC of 0.75 [0.66-0.82]. Admission PRISM-III, PIM-2, and PELOD should not be used for pre-ECMO risk adjustment because they do not discriminate death. Extracorporeal membrane oxygenation population-derived scores should be used to risk adjust ECMO populations as opposed to general PICU population-derived scores.

Antithrombin During Extracorporeal Membrane Oxygenation in Adults: National Survey and Retrospective Analysis

The impact of antithrombin replacement during extracorporeal membrane oxygenation (ECMO) in adults remains unclear. This work comprises a survey, showing that antithrombin is routinely supplemented in many Italian ECMO-Centers, and a retrospective analysis on 66 adults treated with veno-venous ECMO and unfractionated heparin at our Institution. Twenty-four to 72 h after the beginning of ECMO, antithrombin activity was ≤70% in 47/66 subjects and activated partial thromboplastin time (aPTT) ratio was <1.5 in 20/66 subjects. Activated partial thromboplastin time ratio <1.5 was associated not with lower antithrombin activity (61 ± 17 vs. 63 ± 22%; p = 0.983) but with higher circulating level of C-reactive protein (23 ± 8 vs. 11 ± 9 mg/dl; p < 0.001). In 34 subjects who received antithrombin concentrate, antithrombin activity increased (from 54 ± 9 to 84 ± 13%; p < 0.001); the proportion of subjects with aPTT ratio ≥1.5 increased (from 21/34 [62%] to 31/34 [91%]; p = 0.004); heparin dosage remained constant (from 19 ± 7 to 19 ± 6 IU/kg/h; p = 0.543); and C-reactive protein decreased (from 17 ± 10 to 13 ± 9 mg/dl; p = 0.013). Among those with aPTT ratio <1.5, aPTT ratio remained <1.5 in 3 out of 13 subjects. Antithrombin is frequently supplemented during veno-venous ECMO although low antithrombin activity does not constantly impede, and antithrombin replacement does not constantly ensure, reaching the target aPTT ratio. Inflammation possibly affects the individual response to heparin.

Pediatric Plasma and Platelet Transfusions on Extracorporeal Membrane Oxygenation: A Subgroup Analysis of Two Large International Point-Prevalence Studies and the Role of Local Guidelines

OBJECTIVES

To describe the indications and thresholds for plasma and platelet transfusions for pediatric extracorporeal membrane oxygenation, to compare responses to these transfusions and to describe institutional protocols directing their administration.

DESIGN

Subgroup analysis of two prospective, observational studies paired with survey of sites who enrolled subjects into this cohort.

SETTING

Fifty-one PICUs in 13 countries.

PATIENTS

Children (3 d to 16 yr old) were enrolled if they received a plasma or platelet transfusion while on extracorporeal membrane oxygenation during one of the predefined screening weeks.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Forty-eight children on extracorporeal membrane oxygenation received plasma transfusions and 90 received platelet transfusions. Sixty percent of plasma transfusions (29/48) and 79% of the platelet transfusions (71/90) were given for prophylaxis of bleeding. The median (interquartile range) international normalized ratio prior to transfusion, known in 75% of the patients (36/48), was 1.45 (1.20-1.85). The median (interquartile range) total platelet count prior to transfusion, known in all of the patients, was 70 × 10/L (52-90 × 10/L). The international normalized ratio and total platelet count values prior to transfusion did not vary based on bleeding versus nonbleeding indications. The median (interquartile range) reduction in international normalized ratio for mild coagulopathies (international normalized ratio ≤ 2.0) was 0.1 (0.4-0), median (interquartile range) increase in fibrinogen was 0.2 g/L (0.1-0.4 g/L) and median increase in total platelet count was 34 × 10/L (10-74 × 10/L). Through the course of their admission, children supported by extracorporeal membrane oxygenation received a total median (interquartile range) dose of 75 mL/kg (36-159 mL/kg) of plasma transfusions and 92 mL/kg (42-239 mL/kg) of platelet transfusions. Institutional protocols varied but provided guidance for platelet transfusions more commonly.

CONCLUSIONS

Children supported by extracorporeal membrane oxygenation receive large volumes of plasma and platelet transfusions with some institutional guidance in the form of protocols, but significant variation in practice. Interventional studies are necessary to provide evidence to direct the transfusion of hemostatic products in children supported by extracorporeal membrane oxygenation.

Impact of delayed systemic heparinization on postoperative bleeding and thromboembolism during post-cardiotomy extracorporeal membrane oxygenation in neonates

INTRODUCTION

Veno-arterial extracorporeal membrane oxygenation is well-established for pediatric patients with post-cardiotomy heart failure. However, extracorporeal membrane oxygenation support is associated with major complications, that is, hemorrhage and thromboembolism. We seek to report our experience with delayed systemic heparinization during neonatal cardiac extracorporeal membrane oxygenation and its impact on bleeding and thromboembolism.

METHODS

We retrospectively identified 15 consecutive neonates who were placed on extracorporeal membrane oxygenation after congenital heart surgery during a period of 3 years (2015-2017). Our anticoagulation protocol consisted of full heparin reversal by protamine after switching from cardiopulmonary bypass to extracorporeal membrane oxygenation (target activated clotting time: 120 ± 20 seconds). Administration of systemic heparinization was delayed until postoperative drainage volume declined to <1 mL/kg/h. Primary study endpoints were thromboembolism, bleeding, and requirement of blood products on extracorporeal membrane oxygenation.

RESULTS

Our cohort (mean age: 13 ± 2.6 days; mean weight: 3.1 ± 0.3 kg; 66.7% male) required post-cardiotomy extracorporeal membrane oxygenation with a mean support time of 4.5 ± 2.2 days. Systemic heparinization was delayed averagely for 18.1 ± 9.3 hours. No thromboembolic events were observed on extracorporeal membrane oxygenation or after weaning. Relevant surgical site bleeding occurred in two patients (13.3%) requiring re-thoracotomy on the first postoperative day. Analysis of transfusion volumes revealed 24.5 ± 21.9 mL/kg/d mean packed red blood cells, 9.6 ± 7.1 mL/kg/d mean fresh frozen plasma, and 7.5 ± 5.7 mL/kg/d mean platelets. In-hospital survival was 86.6% (n = 13).

CONCLUSION

In this retrospective analysis, the results of delayed systemic heparinization in neonatal post-cardiotomy extracorporeal membrane oxygenation could lead one to conclude that this routine is safe and favorable with low risk for thromboembolic events, reduced postoperative hemorrhage, and reduced blood product utilization.

Platelet Transfusion Practice and Related Outcomes in Pediatric Extracorporeal Membrane Oxygenation

OBJECTIVE

To describe factors associated with platelet transfusion during pediatric extracorporeal membrane oxygenation and the relationships among platelet transfusion, complications, and mortality.

DESIGN

Secondary analysis of data collected prospectively by the Collaborative Pediatric Critical Care Research Network between December 2012 and September 2014.

SETTING

Eight Collaborative Pediatric Critical Care Research Network-affiliated hospitals.

PATIENTS

Age less than 19 years old and treated with extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 511 children, 496 (97.1%) received at least one platelet transfusion during extracorporeal membrane oxygenation. Neonatal age, venoarterial extracorporeal membrane oxygenation, and various acute and chronic diagnoses were associated with increased average daily platelet transfusion volume (milliliters per kilogram body weight). On multivariable analysis, average daily platelet transfusion volume was independently associated with mortality (per 1 mL/kg; odds ratio, 1.05; CI, 1.03-1.08; p < 0.001), whereas average daily platelet count was not (per 1 × 10/L up to 115 × 10/L; odds ratio, 1.00; CI, 0.98-1.01; p = 0.49). Variables independently associated with increased daily bleeding risk included increased platelet transfusion volume on the previous extracorporeal membrane oxygenation day, a primary cardiac indication for extracorporeal membrane oxygenation, adolescent age, and an acute diagnosis of congenital cardiovascular disease. Variables independently associated with increased daily thrombotic risk included increased platelet transfusion volume on the previous extracorporeal membrane oxygenation day and venoarterial extracorporeal membrane oxygenation. Variables independently associated with decreased daily thrombotic risk included full-term neonatal age and an acute diagnosis of airway abnormality.

CONCLUSIONS

Platelet transfusion was common in this multisite pediatric extracorporeal membrane oxygenation cohort. Platelet transfusion volume was associated with increased risk of mortality, bleeding, and thrombosis.

The Use of Bivalirudin in Pediatric Cardiac Surgery and in the Interventional Cardiology Suite

Anticoagulation is an essential component for patients undergoing cardiopulmonary bypass or extracorporeal membrane oxygenation and for those with ventricular assist devices. However, thrombosis and bleeding are common complications. Heparin continues to be the agent of choice for most patients, likely owing to practitioners' comfort and experience and the ease with which the drug's effects can be reversed. However, especially in pediatric cardiac surgery, there is increasing interest in using bivalirudin as the primary anticoagulant. This drug circumvents certain problems with heparin administration, such as heparin resistance and heparin-induced thrombocytopenia, but it comes with additional challenges. In this manuscript, the authors review the literature on the emerging role of bivalirudin in pediatric cardiac surgery, including its use with cardiopulmonary bypass surgery, extracorporeal membrane oxygenation, ventricular assist devices, and interventional cardiology. Moreover, they provide an overview of bivalirudin's pharmacodynamics and monitoring methods.

Clinical controversies in anticoagulation monitoring and antithrombin supplementation for ECMO

During extracorporeal membrane oxygenation (ECMO), a delicate balance is required to titrate systemic anticoagulation to prevent thrombotic complications within the circuit and prevent bleeding in the patient. Despite focused efforts to achieve this balance, the frequency of both thrombotic and bleeding events remains high. Anticoagulation is complicated to manage in this population due to the complexities of the hemostatic system that are compounded by age-related developmental hemostatic changes, variable effects of the etiology of critical illness on hemostasis, and blood-circuit interaction. Lack of high-quality data to guide anticoagulation management in ECMO patients results in marked practice variability among centers. One aspect of anticoagulation therapy that is particularly challenging is the use of antithrombin (AT) supplementation for heparin resistance. This is especially controversial in the neonatal and pediatric population due to the baseline higher risk of bleeding in this cohort. The indication for AT supplementation is further compounded by the potential inaccuracy of the diagnosis of heparin resistance based on the standard laboratory parameters used to assess heparin effect. With concerns regarding the adverse impact of bleeding and thrombosis, clinicians and institutions are faced with making difficult, real-time decisions aimed at optimizing anticoagulation in this setting. In this clinically focused review, the authors discuss the complexities of anticoagulation monitoring and therapeutic intervention for patients on ECMO and examine the challenges surrounding AT supplementation given both the historical and current perspectives summarized in the literature on these topics.

Hemostatic Testing in Critically Ill Infants and Children

Children with critical illness frequently manifest imbalances in hemostasis with risk of consequent bleeding or pathologic thrombosis. Traditionally, plasma-based tests measuring clot formation by time to fibrin clot generation have been the "gold standard" in hemostasis testing. However, these tests are not sensitive to abnormalities in fibrinolysis or in conditions of enhanced clot formation that may lead to thrombosis. Additionally, they do not measure the critical roles played by platelets and endothelial cells. An added factor in the evaluation of these plasma-based tests is that in infants and young children plasma levels of many procoagulant and anticoagulant proteins are lower than in older children and adults resulting in prolonged clot generation times in spite of maintaining a normal hemostatic "balance." Consequently, newer assays directly measuring thrombin generation in plasma and others assessing the stages hemostasis including clot initiation, propagation, and fibrinolysis in whole blood by viscoelastic methods are now available and may allow for a global measurement of the hemostatic system. In this manuscript, we will review the processes by which clots are formed and by which hemostasis is regulated, and the rationale and limitations for the more commonly utilized tests. We will also discuss selected newer tests available for the assessment of hemostasis, their "pros" and "cons," and how they compare to the traditional tests of coagulation in the assessment and management of critically ill children.

The Developing Balance of Thrombosis and Hemorrhage in Pediatric Surgery: Clinical Implications of Age-Related Changes in Hemostasis

Bleeding and thrombosis in critically ill infants and children is a vexing clinical problem. Despite the relatively low incidence of bleeding and thrombosis in the overall pediatric population relative to adults, these critically ill children face unique challenges to hemostasis due to extreme physiologic derangements, exposure of blood to foreign surfaces and membranes, and major vascular endothelial injury or disruption. Caring for pediatric patients on extracorporeal support, recovering from solid organ transplant or invasive surgery, and after major trauma is often complicated by major bleeding or clotting events. As our ability to care for the youngest and sickest of these children increases, the gaps in our understanding of the clinical implications of developmental hemostasis have become increasingly important. We review the current understanding of the development and function of the hemostatic system, including the complex and overlapping interactions of coagulation proteins, platelets, fibrinolysis, and immune mediators from the neonatal period through early childhood and to young adulthood. We then examine scenarios in which our ability to effectively measure and treat coagulation derangements in pediatric patients is limited. In these clinical situations, adult therapies are often extrapolated for use in children without taking age-related differences in pediatric hemostasis into account, leaving clinicians confused and impacting patient outcomes. We discuss the limitations of current coagulation testing in pediatric patients before turning to emerging ideas in the measurement and management of pediatric bleeding and thrombosis. Finally, we highlight opportunities for future research which take into account this developing balance of bleeding and thrombosis in our youngest patients.

ECMO for Neonatal Sepsis in 2019

Sepsis and septic shock in newborns causes mortality and morbidity depending on the organism and primary site. ECMO provides cardiorespiratory support to allow adequate organ perfusion during the time for antibiotics and source control surgery (if needed) to occur. ECMO mode and cannulation site vary depending on support required and local preference. Earlier and more aggressive use of ECMO can improve survival.

Challenges in Maintaining the Hemostatic Balance in Children Undergoing Extracorporeal Membrane Oxygenation: A Systematic Literature Review

Background: Despite advances in technology and clinical experience, the incidence of hemostatic complications, including bleeding and thrombosis, remains high in children supported with extracorporeal membrane oxygenation (ECMO). These hemostatic complications are important to prevent, since they are associated with increased morbidity and mortality. This systematic literature review aims to outline the most important risk factors for hemostatic complications in children undergoing ECMO treatment, to summarize the reported alternative anticoagulant drugs used in pediatric ECMO and to describe studied associations between coagulation tests and hemostatic complications. Methods: A literature search was performed in Embase, Medline, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and Google Scholar in February 2020. Included studies were studies evaluating children (<18 years old) treated with ECMO, and studies evaluating risk factors for hemostatic complications, alternative anticoagulants, or the association between coagulation tests and hemostatic complications. Results: Out of 1,152 articles, 35 studies were included. Thirteen out of 49 risk factors were investigated in three or more studies. Most consistent results were found regarding ECMO duration and pH. However, evidence for risk factors was equivocal in the majority of studies, which is explained by the variability of populations studied, definitions of hemostatic complications, ECMO circuits, anticoagulation protocols, transfusion triggers and monitoring of anticoagulation. Five studies described alternative anticoagulants, including bivalirudin (n = 3), argatroban (n = 1) and FUT (n = 1). Higher anti-factor Xa levels were associated with less clotting events in one of nine studies, investigating the association between tests and hemostatic complications. Two studies revealed an association between anti-factor Xa assay-based protocols and a decreased number of transfusions, bleedings and need for circuit change. Conclusion: Studies regarding risk factors showed conflicting results and a few retrospective studies reported the use of new anticoagulants and data on coagulation tests in relation to hemostatic complications. To decrease hemostatic complications in ECMO children, prospective multicenter studies are needed with clear bleeding and thrombotic definitions, and the best possible standardization of ECMO circuits used, anticoagulation protocols, and transfusion triggers.

Mortality and Factors Associated With Hemorrhage During Pediatric Extracorporeal Membrane Oxygenation

OBJECTIVES

To quantify and identify factors associated with bleeding events during pediatric extracorporeal membrane oxygenation.

DESIGN

Retrospective cohort study with primary outcome of bleeding days on extracorporeal membrane oxygenation.

SETTING

Single tertiary care children's hospital.

SUBJECTS

One-hundred twenty-two children supported with extracorporeal membrane oxygenation for greater than 12 hours during January 2015 through December 2016.

INTERVENTIONS

Bleeding days were identified if mediastinal or cannula site exploration, activated factor VII administration, gastrointestinal, pulmonary, or intracranial hemorrhages occurred. Logistic regression was used to assess factors associated with bleeding days.

MEASUREMENTS AND MAIN RESULTS

Study population was identified from institutional extracorporeal membrane oxygenation database. Clinical, laboratory, and survival data were obtained from medical records. Only data from patients' first extracorporeal membrane oxygenation run were used. One-hundred twenty-two patients with median age of 17 weeks (interquartile range, 1-148 wk) were analyzed. Congenital heart disease (n = 56, 46%) was the most common diagnosis. Bleeding days comprised 179 (16%) of the 1,121 observed extracorporeal membrane oxygenation-patient-days. By extracorporeal membrane oxygenation day 4, 50% of users had experienced a bleeding day. Central rather than peripheral cannulation (odds ratio, 2.58; 95% CI, 1.47-4.52; p < 0.001), older age (odds ratio, 1.31 per increased week; 95% CI, 1.14-1.52; p < 0.001), higher lactate (odds ratio, 1.08 per 1 mmol/L increase; 95% CI, 1.05-1.12; p < 0.001), and lower platelets (odds ratio, 0.87 per 25,000 cell/μL increase; 95% CI, 0.77-0.99; p = 0.005) were associated with bleeding days. Patients who experienced more frequent bleeding (> 75th percentile) had fewer ventilator-free and hospital-free days in the 60 days after cannulation (0 vs 31; p = 0.002 and 0 vs 0; p = 0.008) and higher in-hospital mortality (68 vs 34%; p < 0.001).

CONCLUSIONS

Central cannulation, older age, low platelets, and high lactate are associated with bleeding days during pediatric extracorporeal membrane oxygenation. Patients who bleed more frequently during extracorporeal membrane oxygenation have higher in-hospital mortality, longer technological dependence, and reduced hospital-free days.

The impact of shear stress on device-induced platelet hemostatic dysfunction relevant to thrombosis and bleeding in mechanically assisted circulation

The aim of this study was to examine the impact of the nonphysiological shear stress (NPSS) on platelet hemostatic function relevant to thrombosis and bleeding in mechanically assisted circulation. Fresh human blood was circulated for four hours in in vitro circulatory flow loops with a CentriMag blood pump operated under a flow rate of 4.5 L/min against three pressure heads (70 mm Hg, 150 mm Hg, and 350 mm Hg) at 2100, 2800, and 4000 rpm, respectively. Hourly blood samples from the CentriMag pump-assisted circulation loops were collected and analyzed for glycoprotein (GP) IIb/IIIa activation and receptor shedding of GPVI and GPIbα on the platelet surface with flow cytometry. Adhesion of platelets to fibrinogen, collagen, and von Willebrand factor (VWF) of the collected blood samples was quantified with fluorescent microscopy. In parallel, mechanical shear stress fields within the CentriMag pump operated under the three conditions were assessed by computational fluid dynamics (CFD) analysis. The experimental results showed that levels of platelet GPIIb/IIIa activation and platelet receptor shedding (GPVI and GPIbα) in the blood increased with increasing the circulation time. The levels of platelet activation and loss of platelet receptors GPVI and GPIbα were consistently higher with higher pressure heads at each increasing hour in the CentriMag pump-assisted circulation. The platelet adhesion on fibrinogen increased with increasing the circulation time for all three CentriMag operating conditions and was correlated well with the level of platelet activation. In contrast, the platelet adhesion on collagen and VWF decreased with increasing the circulation time under all the three conditions and was correlated well with the loss of the receptors GPVI and GPIbα on the platelet surface, respectively. The CFD results showed that levels of shear stresses inside the CentriMag pump under all three operating conditions exceeded the maximum level of shear stress in the normal physiological circulation and were strongly dependent on the pump operating condition. The level of platelet activation and loss of key platelet adhesion receptors (GPVI and GPIbα) were correlated with the level of NPSS generated by the CentriMag pump, respectively. In summary, the level of NPSS associated with pump operating condition is a critical determinant of platelet dysfunction in mechanically assisted circulation.

Blood product transfusion and mortality in neonatal extracorporeal membrane oxygenation

BACKGROUND

Neonates receiving extracorporeal membrane oxygenation (ECMO) support are transfused large volumes of red blood cells (RBCs) and platelets (PLTs). Transfusions are often administered in response to specific, but largely unstudied thresholds. The aim of this study is to examine the relationship between RBC and PLT transfusion rates and mortality in neonates receiving ECMO support.

STUDY DESIGN AND METHODS

We retrospectively examined outcomes of neonates receiving ECMO support in the neonatal intensive care unit (NICU) for respiratory failure between 2010 and 2016 at a single quaternary-referral NICU. We examined the association between RBC and PLT transfusion rate (mL per kg per day) and in-hospital mortality, adjusting for confounding by using a validated composite baseline risk score (Neo-RESCUERS).

RESULTS

Among the 110 neonates receiving ECMO support, in-hospital mortality was 28%. The median RBC transfusion rate (mL/kg/d) after cannulation was greater among non-survivors, compared to survivors: 12.4 (IQR 9.3-16.2) versus 7.3 (IQR 5.1-10.3), p < 0.001. Similarly, PLT transfusion rate was greater among non-survivors: 22.9 (9.3-16.2) versus 12.1 (8.4-20.1), p = 0.02. After adjusting for baseline mortality risk, both RBC transfusion (adjusted relative risk per 5 mL/kg/d increase: 1.33; 95% CI 1.05-1.69, p = 0.02) and PLT transfusion (adjusted relative risk per 5 mL/kg/d increase: 1.12; 95% CI 1.02-1.23, p = 0.02) were both associated with in-hospital mortality.

CONCLUSIONS

RBC and PLT transfusion rates are associated with in-hospital mortality among neonates receiving ECMO. These data provide a basis for future studies evaluating more restrictive transfusion practices for neonates receiving ECMO support.

Outcomes of Infants Supported With Extracorporeal Membrane Oxygenation Using Centrifugal Versus Roller Pumps: An Analysis From the Extracorporeal Life Support Organization Registry

OBJECTIVES

To determine whether mortality differs between roller and centrifugal pumps used during extracorporeal membrane oxygenation in infants weighing less than 10 kg.

DESIGN

Retrospective propensity-matched cohort study.

SETTING

All extracorporeal membrane oxygenation centers reporting to the Extracorporeal Life Support Organization.

PATIENTS

All patients less than 10 kg supported on extracorporeal membrane oxygenation during 2011-2016 within Extracorporeal Life Support Organization Registry.

INTERVENTIONS

Centrifugal and roller pump recipients were propensity matched (1:1) based on predicted probability of receiving a centrifugal pump using demographic variables, indication for extracorporeal membrane oxygenation, central versus peripheral cannulation, and pre-extracorporeal membrane oxygenation patient management.

MEASUREMENTS AND MAIN RESULTS

A total of 12,890 patients less than 10 kg were supported with extracorporeal membrane oxygenation within the Extracorporeal Life Support Organization registry during 2011-2016. Patients were propensity matched into a cohort of 8,366. Venoarterial and venovenous extracorporeal membrane oxygenation runs were propensity matched separately. The propensity-matched cohorts were similar except earlier year of extracorporeal membrane oxygenation (standardized mean difference, 0.49) in the roller pump group. Within the propensity-matched cohort, survival to discharge was lower in the centrifugal pump group (57% vs 59%; odds ratio, 0.91; 95% CI, 0.83-0.99; p = 0.04). Hemolytic, infectious, limb injury, mechanical, metabolic, neurologic, pulmonary, and renal complications were more frequent in the centrifugal pump group. Hemorrhagic complications were similar between groups. Hemolysis mediated the relationship between centrifugal pumps and mortality (indirect effect, 0.023; p < 0.001).

CONCLUSIONS

In this propensity score-matched cohort study of 8,366 extracorporeal membrane oxygenation recipients weighing less than 10 kg, those supported with centrifugal pumps had increased mortality and extracorporeal membrane oxygenation complications. Hemolysis was evaluated as a potential mediator of the relationship between centrifugal pump use and mortality and met criteria for full mediation.

Exogenous supplementation of antithrombin III in adult and pediatric patients receiving extracorporeal membrane oxygenation

Background:

Antithrombin III deficiency can occur with heparin anticoagulation during extracorporeal membrane oxygenation leading to heparin resistance. Antithrombin III supplementation has been shown to improve anticoagulation; however, there is no consensus on appropriate administration. We described the effect of antithrombin III supplementation on coagulation parameters in adult and pediatric extracorporeal membrane oxygenation patients.

Methods:

We conducted a retrospective cohort study using electronic medical records of patients who received ⩾1 dose of antithrombin III during extracorporeal membrane oxygenation while on continuous heparin. Endpoints included the change in anti-Xa levels and antithrombin III activity at −6 versus 6 h relative to antithrombin III supplementation, and heparin infusion rates at 6 versus 12 h after antithrombin III supplementation.

Results:

Eighteen patients receiving 36 antithrombin III administrations were analyzed. Mean (standard deviation) anti-Xa values at −6 versus 6 h were 0.15 (0.07) versus 0.24 (0.15) IU/mL ( p-value: 0.250) for pediatrics and 0.19 (0.22) versus 0.31 (0.27) IU/mL ( p-value: 0.052) for adults. Mean (standard deviation) plasma antithrombin III activity at the same intervals were 32% (14.2%) versus 66.8% (25.1%; p-value: 0.062) for pediatrics and 30.3% (14%) versus 52.8% (8.1%; p-value: 0.094) for adults. Mean (standard deviation) heparin rates at 6 versus 12 h after antithrombin III for pediatrics were 23.6 (6) versus 23.5 (6.5) units/kg/h ( p-value: 0.728), and 15.3 (6.6) versus 13.5 (8) units/kg/h ( p-value: 0.188) for adults.

Conclusion:

Administration of antithrombin III improved anti-Xa levels in both populations, however, did not significantly reduce heparin rates. Our findings suggest that the use of antithrombin III restores heparin responsiveness in patients with low antithrombin III activity and low anti-Xa activity.

Bleeding and Thrombosis With Pediatric Extracorporeal Life Support: A Roadmap for Management, Research, and the Future From the Pediatric Cardiac Intensive Care Society: Part 2

OBJECTIVES

To make recommendations on improving understanding of bleeding and thrombosis with pediatric extracorporeal life support including future research directions.

DATA SOURCES

Evaluation of literature and consensus conferences of pediatric critical care and extracorporeal life support experts.

STUDY SELECTION

A team of 10 experts with pediatric cardiac and extracorporeal membrane oxygenation experience and expertise met through the Pediatric Cardiac Intensive Care Society to review current knowledge and make recommendations for future research to establish "best practice" for anticoagulation management related to extracorporeal life support.

DATA EXTRACTION/DATA SYNTHESIS

This white paper focuses on clinical understanding and limitations of current strategies to monitor anticoagulation. For each test of anticoagulation, limitations of current knowledge are addressed and future research directions suggested.

CONCLUSIONS

No consensus on best practice for anticoagulation monitoring exists. Structured scientific evaluation to answer questions regarding anticoagulation monitoring and bleeding and thrombotic events should occur in multicenter studies using standardized approaches and well-defined endpoints. Outcomes related to need for component change, blood product administration, healthcare outcome, and economic assessment should be incorporated into studies. All centers should report data on patient receiving extracorporeal life support to a registry.

Inotrope Needs in Neonates Requiring Extracorporeal Membrane Oxygenation for Respiratory Failure

OBJECTIVE

To evaluate how inotropic requirements in neonates with respiratory failure are affected by extracorporeal membrane oxygenation (ECMO) mode and whether high requirements predict mortality.

STUDY DESIGN

This retrospective chart review included all neonates undergoing ECMO for primary respiratory failure from 2010 to 2016 at a single institution. The vasoactive inotropy score (VIS) was calculated as described in the literature. Data were analyzed with descriptive statistics and univariate analyses.

RESULTS

Of the 110 identified neonates, 96 underwent venovenous (VV) (87%), 11 (10%) venoarterial, and 3 (3%) converted from VV to venoarterial. The median precannulation VIS score was 33.02 for patients who underwent VV compared with 28.93 for venoarterial (P = .25) and 15 for infants converted. VIS decreased dramatically by 4 hours of ECMO in both groups. The VIS before cannulation was similar in survivors and nonsurvivors, but was significantly higher in nonsurvivors after 24 hours of ECMO (median VIS, 12 [IQR, 8-25] vs 8 [IQR, 3.0-14.5]; P = .035) and at decannulation (10 [IQR, 7-19] vs 3 [IQR, 0-7]; P < .001).

CONCLUSIONS

Neonates with respiratory failure can be successfully managed on VV ECMO even with considerable vasoactive requirements. Vasoactive requirement after 24 hours of ECMO was predictive of mortality.

Platelet Phenotype and Function in the Setting of Pediatric Extracorporeal Membrane Oxygenation (ECMO): A Systematic Review

Background: Despite increasing technical improvement and extracorporeal membrane oxygenation (ECMO)-related knowledge over the past three decades, morbidity and mortality associated with bleeding and clotting complications remain high in pediatric patients undergoing ECMO. Platelets, a key element of the coagulation system, have been proposed to be the main cause of coagulopathy in the setting of ECMO. This systematic review aims to summarize and discuss the existing knowledge of platelet phenotype and function in the pediatric ECMO population. Methods: A systematic review was conducted for the Embase, Medline, and PubMed databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Results: The detailed study selection process yielded a total of 765 studies and only 3 studies that fulfilled the selection criteria were included in this review. Techniques used to assess platelet function in the three existing studies included platelet aggregometry, flow cytometry, and thromboelastography-platelet mapping. The finding that is common to the three studies is reduced platelet function in pediatric patients during ECMO either compared to before the initiation of ECMO or in non-survivors compared to survivors. Two studies demonstrated reduced platelet aggregation that are irreversible by platelet transfusion during ECMO. Two studies reported bleeding events and mortality in children on ECMO and none of the studies investigated thrombotic events. Conclusions: This systematic review demonstrates the extremely limited information available for platelet phenotype and function in the pediatric ECMO population. Evidence from the existing literature suggests reduced platelet aggregation and increased platelet activation in children during ECMO. However, this needs to be interpreted with care due to the limitations associated with the techniques used for platelet function testing. Furthermore, the association between platelet dysfunction and clinical outcomes in the pediatric ECMO population remains elusive. Multiple research gaps have been identified when it comes to the knowledge of platelet phenotype and function of children on ECMO, highlighting the need for robust, well-designed studies in this setting.

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.

Patterns of Medication Exposure in Children on Extracorporeal Membrane Oxygenation: A Step in Prioritizing Future Pharmacologic Studies

To identify medications administered to pediatric patients on extracorporeal membrane oxygenation and to review the available pharmacokinetics and pharmacodynamics literature for the most commonly administered medications.

DESIGN

Retrospective single-center study.

SETTING

ICUs at Children's Hospital of Philadelphia.

PATIENTS

Pediatric patients supported by extracorporeal membrane oxygenation between October 1, 2014, and September 30, 2018.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Drug exposure was described according to age group (< 1 mo, 1 mo to < 2 yr, 2 to < 12 yr, and > 12 yr) and ICU (cardiac, neonatal, pediatric). The association of drug exposure with patient's characteristics was examined using one-way analysis of variance for categorical variables and linear regression for continuous variables. All pharmacokinetics and pharmacodynamics literature for the 50 most commonly administered medications on extracorporeal membrane oxygenation was reviewed, with inclusion of studies that reported dosing regimens in conjunction with pharmacokinetics or pharmacodynamics data. A total of 179 different medications were administered to 254 children. Cumulative drug exposure increased with the duration of extracorporeal membrane oxygenation from a median (interquartile) of 10 drugs (6-14) at 1 week to 31 drugs (21-45) at 5 weeks following cannulation. There were significant differences in total drug exposure between age groups and ICUs. With exclusion of in vitro studies, published literature was available to support the use of 40% (20/50) of the most commonly administered medications. Dosing guidance was available for 20% (10/50) of medications and was primarily based on simulations and retrospective studies focusing on neonates and infants.

CONCLUSIONS

This study highlights specific needs for future pharmacokinetics and pharmacodynamics studies. Dosing guidelines are essential to optimize the care of critically ill children supported by extracorporeal membrane oxygenation.

Hurdles to Cardioprotection in the Critically Ill

Cardiovascular disease is the largest contributor to worldwide mortality, and the deleterious impact of heart failure (HF) is projected to grow exponentially in the future. As heart transplantation (HTx) is the only effective treatment for end-stage HF, development of mechanical circulatory support (MCS) technology has unveiled additional therapeutic options for refractory cardiac disease. Unfortunately, despite both MCS and HTx being quintessential treatments for significant cardiac impairment, associated morbidity and mortality remain high. MCS technology continues to evolve, but is associated with numerous disturbances to cardiac function (e.g., oxidative damage, arrhythmias). Following MCS intervention, HTx is frequently the destination option for survival of critically ill cardiac patients. While effective, donor hearts are scarce, thus limiting HTx to few qualifying patients, and HTx remains correlated with substantial post-HTx complications. While MCS and HTx are vital to survival of critically ill cardiac patients, cardioprotective strategies to improve outcomes from these treatments are highly desirable. Accordingly, this review summarizes the current status of MCS and HTx in the clinic, and the associated cardiac complications inherent to these treatments. Furthermore, we detail current research being undertaken to improve cardiac outcomes following MCS/HTx, and important considerations for reducing the significant morbidity and mortality associated with these necessary treatment strategies.

Lobectomy on ECMO as a Life-Saving Procedure following Necrotizing Pneumonia in a Toddler: A Case Study

Necrotizing pneumonia is a severe form of pneumonia that is mainly treated with conservative treatment, including antibiotics. We report a unique case of necrotizing pneumonia due to group A streptococcus infection in an 18-month-old boy who required extracorporeal membrane oxygenation (ECMO) support. Following surgical lobectomy, the child was weaned off ECMO and recovered uneventfully.

Time to epinephrine treatment is associated with the risk of mortality in children who achieve sustained ROSC after traumatic out-of-hospital cardiac arrest

Background

The benefits of early epinephrine administration in pediatric with nontraumatic out-of-hospital cardiac arrest (OHCA) have been reported; however, the effects in pediatric cases of traumatic OHCA are unclear. Since the volume-related pharmacokinetics of early epinephrine may differ obviously with and without hemorrhagic shock (HS), beneficial or harmful effects of nonselective epinephrine stimulation (alpha and beta agonists) may also be enhanced with early administration. In this study, we aimed to analyze the therapeutic effect of early epinephrine administration in pediatric cases of HS and non-HS traumatic OHCA.

Methods

This was a multicenter retrospective study (2003–2014). Children (aged ≤ 19 years) who experienced traumatic OHCA and were administered epinephrine for resuscitation were included. Children were classified into the HS (blood loss > 30% of total body fluid) and non-HS groups. The demographics, outcomes, postresuscitation hemodynamics (the first hour) after the sustained return of spontaneous circulation (ROSC), and survival durations were analyzed and correlated with the time to epinephrine administration (early < 15, middle 15–30, late > 30 min) in the HS and non-HS groups. Cox regression analysis was used to adjust for risk factors of mortality.

Results

A total of 509 children were included. Most of them (n = 348, 68.4%) had HS OHCA. Early epinephrine administration was implemented in 131 (25.7%) children. In both the HS and non-HS groups, early epinephrine administration was associated with achieving sustained ROSC (both p < 0.05) but was not related to survival or good neurological outcomes (without adjusting for confounding factors). However, early epinephrine administration in the HS group increased cardiac output but induced metabolic acidosis and decreased urine output during the initial postresuscitation period (all p < 0.05). After adjusting for confounding factors, early epinephrine administration was a risk factor of mortality in the HS group (HR 4.52, 95% CI 2.73–15.91).

Conclusion

Early epinephrine was significantly associated with achieving sustained ROSC in pediatric cases of HS and non-HS traumatic OHCA. For children with HS, early epinephrine administration was associated with both beneficial (increased cardiac output) and harmful effects (decreased urine output and metabolic acidosis) during the postresuscitation period. More importantly, early epinephrine was a risk factor associated with mortality in the HS group.

Variable Treatment Approaches for Extracorporeal Membrane Oxygenation Complications in Neonates: A Case Series

Extracorporeal membrane oxygenation complications involving vascular injury or intracardiac thrombosis in neonates are rare. We present a series of unique complications and describe their variable treatments.

Extracorporeal Membrane Oxygenation for Diffuse Alveolar Hemorrhage Caused by Idiopathic Pulmonary Hemosiderosis: A Case Report and a Review of the Literature

Diffuse alveolar hemorrhage (DAH) is a life-threatening condition presenting with hemoptysis, anemia, and diffuse radiographic pulmonary infiltrates; it causes acute respiratory failure. Idiopathic pulmonary hemosiderosis (IPH) is a rare cause of DAH occurring predominantly in children. Bleeding is often considered to be a contraindication for extracorporeal membrane oxygenation (ECMO) due to systemic anticoagulation. We present an 8-year-old girl with DAH caused by IPH. Unfractionated heparin was administered to maintain an activated clotting time of 150 to 180 seconds. The DAH resolved with immunosuppressive therapy, and the patient survived to decannulation. ECMO may be applied as a rescue therapy for DAH even with systemic anticoagulation.

Hemolysis During Pediatric Extracorporeal Membrane Oxygenation: Associations With Circuitry, Complications, and Mortality

OBJECTIVES

To describe factors associated with hemolysis during pediatric extracorporeal membrane oxygenation and the relationships between hemolysis, complications, and mortality.

DESIGN

Secondary analysis of data collected prospectively by the Collaborative Pediatric Critical Care Research Network between December 2012 and September 2014.

SETTING

Three Collaborative Pediatric Critical Care Research Network-affiliated hospitals.

PATIENTS

Age less than 19 years and treated with extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hemolysis was defined based on peak plasma free hemoglobin levels during extracorporeal membrane oxygenation and categorized as none (< 0.001 g/L), mild (0.001 to < 0.5 g/L), moderate (0.5 to < 1.0 g/L), or severe (≥ 1.0 g/L). Of 216 patients, four (1.9%) had no hemolysis, 67 (31.0%) had mild, 51 (23.6%) had moderate, and 94 (43.5%) had severe. On multivariable analysis, variables independently associated with higher daily plasma free hemoglobin concentration included the use of in-line hemofiltration or other continuous renal replacement therapy, higher hemoglobin concentration, higher total bilirubin concentration, lower mean heparin infusion dose, lower body weight, and lower platelet count. Using multivariable Cox modeling, daily plasma free hemoglobin was independently associated with development of renal failure during extracorporeal membrane oxygenation (defined as creatinine > 2 mg/dL [> 176.8 μmol/L] or use of in-line hemofiltration or continuous renal replacement therapy) (hazard ratio, 1.04; 95% CI, 1.02-1.06; p < 0.001), but not mortality (hazard ratio, 1.01; 95% CI, 0.99-1.04; p = 0.389).

CONCLUSIONS

Hemolysis is common during pediatric extracorporeal membrane oxygenation. Hemolysis may contribute to the development of renal failure, and therapies used to manage renal failure such as in-line hemofiltration and other forms of continuous renal replacement therapy may contribute to hemolysis. Hemolysis was not associated with mortality after controlling for other factors. Monitoring for hemolysis should be a routine part of extracorporeal membrane oxygenation practice, and efforts to reduce hemolysis may improve patient care.

Neonatal ECMO

Extracorporeal membrane oxygenation (ECMO) is becoming increasingly utilized to manage neonates with cardiac and respiratory failure. The procedure involves extensive anticoagulation in a sick neonate with underlying disease pathology. In addition, the immature hemostatic system in the neonate adds to the complexity of titrating the necessary anticoagulation. This places the infant at greater risk for life threatening hemorrhage and thrombosis. Managing anticoagulation in these infants is extremely challenging and needs the expertise of a physician with a thorough knowledge of the intricacies of developmental hemostasis and limitations of the current laboratory techniques available to manage anticoagulation. This article provides a brief overview of the developing hemostatic system of the neonate and the challenges associated with managing anticoagulation in this vulnerable population of patients.

Effect of pump type on outcomes in neonates with congenital diaphragmatic hernia requiring ECMO

PURPOSE

With the exception of neonatal respiratory failure, most centers are now using centrifugal over roller-type pumps for the delivery of extracorporeal membrane oxygenation (ECMO). Evidence supporting the use of centrifugal pumps specifically in infants with congenital diaphragmatic hernia (CDH) remains lacking. We hypothesized that the use of centrifugal pumps in infants with CDH would not affect mortality or rates of severe neurologic injury (SNI).

METHODS

Infants with CDH were identified within the ELSO registry (2000-2016). Patients were then divided into those undergoing ECMO with rollertype pumps or centrifugal pumps. Patients were matched based on propensity score (PS) for the ECMO pump type based on pre-ECMO covariates. This was done for all infants and separately for each ECMO mode, venovenous (VV) and venoarterial (VA) ECMO.

RESULTS

We identified 4,367 infants who were treated with either roller or centrifugal pumps from 2000-2016. There was no difference in mortality or SNI between the two pump types in any of the groups (all infants, VA-ECMO infants, VV-ECMO infants). However, there was at least a six-fold increase in the odds of hemolysis for centrifugal pumps in all groups: all infants (odds ratio [OR] 6.99, p<0.001), VA-ECMO infants (OR 8.11, p<0.001 and VV-ECMO infants (OR 9.66, p<0.001).

CONCLUSION

For neonates with CDH requiring ECMO, there is no survival advantage or difference in severe neurologic injury between those receiving roller or centrifugal pump ECMO. However, there is a significant increase in red blood cell hemolysis associated with centrifugal ECMO support.

Comparing Percutaneous to Open Access for Extracorporeal Membrane Oxygenation in Pediatric Respiratory Failure

OBJECTIVES

Evaluate trends in method of access (percutaneous cannulation vs open cannulation) for pediatric extracorporeal membrane oxygenation and determine the effects of cannulation method on morbidity and mortality.

DESIGN

Retrospective cohort study.

SETTING AND SUBJECTS

The Extracorporeal Life Support Organization's registry was queried for pediatric patients on extracorporeal membrane oxygenation for respiratory failure from 2007 to 2015.

INVERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 3,501 patients identified, 77.2% underwent open cannulation, with the frequency of open cannulation decreasing over the study period from approximately 80% to 70% (p < 0.001). Percutaneous cannulation patients were more commonly male (24.2% vs 21.5%; p = 0.01), older (average 7.6 vs 4.5 yr; p < 0.001), and heavier (average 33.0 vs 20.2 kg; p < 0.001). Subset analysis of patients on venovenous extracorporeal membrane oxygenation revealed higher rates of mechanical complications due to blood clots (28.9% vs 22.6%; p = 0.003) or cannula problems (18.9% vs 12.7%; p < 0.001), cannula site bleeding (25.3% vs 20.2%; p = 0.01) and increased rates of cannula site repair in the open cannulation cohort. Limb related complications were not significantly different on subset analysis for venovenous extracorporeal membrane oxygenation patients stratified by access site. Logistic regression analysis revealed that method of access was not associated with a difference in mortality.

CONCLUSIONS

The proportion of pediatric patients undergoing percutaneous extracorporeal membrane oxygenation cannulation is increasing. Mechanical and physiologic complications occur with both methods of cannulation, but percutaneous cannulation appears safe in this cohort. Further analysis is needed to evaluate long-term outcomes with this technique.

Neonatal Extracorporeal Membrane Oxygenation Due to Respiratory Failure: A Single Center Experience Over 28 Years

Background: ECMO therapy is worldwide declining in the neonatal population; hence, its therapeutic value is sometimes questioned. Objectives: To report our experience with neonatal ECMO due to respiratory failure over a 28 year time period. Methods: Retrospective single center observational study including all neonates admitted to ECMO due to respiratory failure between 1989 and 2016 at Graz, Austria. Data were collected regarding survival rate, duration of ECMO, complications, length of hospital stay, changes over time, and follow-up. Results: Sixty-seven neonates were admitted and 43 (64%) needed ECMO-median birth weight 3390 grams (range 1810-4150) and gestational age 39 weeks (32-43). Survival rate was 65% (28/43); with higher rates in meconium aspiration syndrome (MAS) 89% vs. congenital diaphragmatic hernia (CDH) 46% and septic shock 44% (p = 0.005 and p = 0.006, respectively). ECMO duration was median 5 days (1-30) and veno-arterial ECMO (52%) dominated. Need for ECMO therapy decreased over time (p < 0.001). Complications occurred in 31 (72%) neonates. Five neonates had cerebral hemorrhages (11.4%) and four had cerebral infarction (9.1%). Of 26 survivors 17 (65%) showed normal neurodevelopmental outcome at median follow-up of 73 months. Motor deficits were present in one case, cognitive deficits in 9 (35%). Median length of hospital stay was 78 days in those with deficits and 29 in those with normal neurodevelopmental outcome (p < 0.001). Conclusions: Survival rate did not change over the study time but indications for ECMO did. Cognitive impairment was the major long-term deficit following neonatal ECMO being associated with longer hospital stay.

Use of Thromboelastography to Predict Thrombotic Complications in Pediatric and Neonatal Extracorporeal Membranous Oxygenation

The objectives of this study were to investigate the correlation between thromboelastography (TEG) and conventional measures of anticoagulation, and to determine optimum values for citrated kaolin TEG R time (TEG RCK) and anti-Xa activity that would minimize both bleeding and thrombotic complications in pediatric and neonatal patients requiring extracorporeal membranous oxygenation (ECMO). A retrospective chart review of patients requiring veno-venous (VV) and venoarterial (VA) ECMO was performed. Combined medical and cardiac ICU within a single-center, tertiary care, freestanding, children's hospital. Non-pregnant patients <18 years and >2 kilograms requiring VV or VA ECMO from July 2013 through July 2015. Anti-Xa (OR = 0.62, 95% CI 0.53-0.72, p < .001) and TEG RCK (OR = 1.19, 95% CI 1.07-1.34, p = .003) were the only independent predictors for a significant thrombotic event. Receiver operating characteristic curves and traditional epidemiological data (sensitivity, specificity, PPV, NPV) were used to determine optimal target Anti-Xa and TEG RCK values. No independent predictors for significant bleeding events were identified in this cohort. A anti-Xa activity of .25 IU/mL (sensitivity = 81%, specificity = 67%, PPV = 81%, NPV = 58%) and TEG RCK time of 17.85 minutes (sensitivity = 84%, specificity = 68%, PPV = 82%, NPV = 59%) were established as the optimal thresholds for preventing thrombotic events. Anti-Xa and TEG RCK were independent predictors of thrombosis in this cohort of pediatric and neonatal ECMO patients. Targeting an anti-Xa activity greater than .25 IU/mL and a TEG RCK greater than 17.85 minutes may minimize the risk of thrombosis in pediatric and neonatal ECMO patients. Future investigation should evaluate targets for anti-Xa and TEG RCK, which additionally minimize the risk of significant bleeding in this patient population.

von Willebrand Factor, Free Hemoglobin and Thrombosis in ECMO

Though extracorporeal membrane oxygenation (ECMO) provides life-saving support, this intervention exposes patients to certain risks. Circulating free hemoglobin (fHb) resulting from mechanically induced hemolysis and insufficient haptoglobin/hemopexin may promote thrombosis within the ECMO circuit. Thrombi in the circuit can result in thromboembolic complications in these patients. Prevention of thrombus formation and propagation in the ECMO circuit may improve clinical outcome. fHb released during hemolysis has been shown to have multiple adverse effects, including thrombosis, but the mechanism by which fHb contributes to thrombosis in an ECMO circuit remains elusive. It is well established that (1) high shear stress generated in the circuit may cause hemolysis, and (2) plasma fibrinogen is adsorbed onto the inner tubing of the ECMO circuit over time. Plasma von Willebrand factor (pVWF) mediates platelet deposition at sites of vascular injury under high shear stress by sensing alterations in the hemodynamic environment. This biophysical property of pVWF that enables hemostasis may also contribute to the pathogenesis of ECMO-induced thrombosis. pVWF contains binding sites for both adsorbed fibrin(ogen) and fHb. High concentrations of fHb increase pVWF-mediated platelet adhesion and thrombus formation on a surface-adsorbed fibrin(ogen) under high shear stress. The molecular mechanism(s) by which fHb drives the conformation of pVWF into a prothrombotic state is currently unknown. Reduction of thrombotic risks during ECMO intervention warrants further investigations into the interaction between pVWF and fHb.

Bleeding, Thrombosis, and Transfusion With Two Heparin Anticoagulation Protocols in Venoarterial ECMO Patients

OBJECTIVE

To compare the incidence of bleeding and thrombosis between adult venoarterial (VA) extracorporeal membrane oxygenation (ECMO) patients managed with an activated clotting time (ACT)-guided heparin anticoagulation protocol and activated partial thromboplastin time (aPTT) protocol.

DESIGN

Retrospective cohort study.

SETTING

Tertiary care, academic medical center.

PARTICIPANTS

Consecutive adult VA ECMO patients during a 6-year period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographic, medical, transfusion, and ECMO data were collected for all patients. Primary study outcomes were bleeding and thrombosis. Secondary outcomes were stroke and in-hospital mortality. One hundred twenty-one patients were included in the cohort. Fifty patients had ACT monitoring, and 71 had aPTT monitoring. There was no difference in the incidence of bleeding or thrombosis between the 2 groups (78.0% v 67.6% for bleeding [p = 0.21] and 16.0% v 19.7% for thrombosis [p = 1.0]). After adjusting for age and total ECMO days, patients managed with ACT received approximately 30% more red blood cell, fresh frozen plasma, and platelet transfusion (all p < 0.05).

CONCLUSION

There is no apparent difference in the incidence rate of bleeding or thrombosis between VA ECMO patients managed with an ACT- or aPTT-guided heparin anticoagulation protocol. Patients managed with an ACT-guided protocol received more blood transfusion, which could reflect greater total bleeding. Future randomized controlled trials would help to elucidate optimal anticoagulation strategies for VA ECMO patients.

RBC Exposure in Pediatric Extracorporeal Membrane Oxygenation: Epidemiology and Factors Associated With Large Blood Transfusion Volume

OBJECTIVES

To quantify and identify factors associated with large RBC exposure in children supported with extracorporeal membrane oxygenation.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary care children's hospital.

PATIENTS

One-hundred twenty-two children supported with extracorporeal membrane oxygenation for greater than 12 hours during January 1, 2015, to December 31, 2016.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Clinical, laboratory, and survival data were obtained from medical records. Only data from patients' first extracorporeal membrane oxygenation run were used. The primary outcome was RBC volume exposure during extracorporeal membrane oxygenation (mL/kg/d). Patients with RBC exposure volume greater than 75th percentile were categorized as "high RBC use" patients. A "bleeding day" was identified if mediastinum or cannula sites were explored and/or Factor VIIa administration, gastrointestinal, pulmonary, or intracranial hemorrhages occurred. Median age was 0.3 years (interquartile range, 0-3 yr). Congenital heart disease (n = 56; 46%) was the most common diagnosis. Median RBC volume transfused during extracorporeal membrane oxygenation was 39 mL/kg/d (interquartile range, 21-66 mL/kg/d). High RBC use patients were more likely be supported by venoarterial extracorporeal membrane oxygenation (100 vs 76%; p = 0.006), have congenital heart disease (68 vs 39%; p = 0.02), and experience bleeding (33 vs 11% d; p < 0.001). High RBC use patients showed a trend toward higher in-hospital mortality (58 vs 37%; p = 0.07). In the multivariable analysis, younger age (-9% per year; 95% CI, -10% to -7%; p < 0.001), more blood draws per day (+8%; 95% CI, 6-11%; p < 0.001), and higher proportion of bleeding days (+22% per 10% increase; 95% CI, 16-29%; p < 0.001) were associated with larger RBC exposure (model R = 0.66).

CONCLUSIONS

Bleeding during extracorporeal membrane oxygenation, frequent laboratory draws, and younger age were associated with increased RBC exposure during extracorporeal membrane oxygenation. Higher transfusion volume was associated with increased mortality.