Laboratory and clinical predictors of thrombosis and hemorrhage in 29 pediatric extracorporeal membrane oxygenation nonsurvivors

Anticoagulation Monitoring and Targets: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic-review informed, modified Delphi consensus regarding anticoagulation monitoring assays and target levels in pediatric extracorporeal membrane oxygenation (ECMO) 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 2021.

STUDY SELECTION

Anticoagulation monitoring of pediatric patients on ECMO.

DATA EXTRACTION

Two authors reviewed all citations independently, with a third independent reviewer resolving any conflicts. Evidence tables were constructed using a standardized data extraction form.

DATA SYNTHESIS

Risk of bias was assessed using the Quality in Prognosis Studies tool or the revised Cochrane risk of bias for randomized trials, as appropriate and 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 clinical recommendations focused on anticoagulation monitoring and targets, using a web-based modified Delphi process to build consensus (defined as > 80% agreement). One weak recommendation, two consensus statements, and three good practice statements were developed and, in all, agreement greater than 80% was reached. We also derived some resources for anticoagulation monitoring for ECMO clinician use at the bedside.

CONCLUSIONS

There is insufficient evidence to formulate optimal anticoagulation monitoring during pediatric ECMO, but we propose one recommendation, two consensus and three good practice statements. Overall, the available pediatric evidence is poor and significant gaps exist in the literature.

Management of Extracorporeal Membrane Oxygenation Anticoagulation in the Perioperative Period: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic review-informed, modified Delphi consensus regarding the management of children on extracorporeal membrane oxygenation (ECMO) undergoing invasive procedures or interventions developed by the Pediatric Anticoagulation on ECMO CollaborativE (PEACE) 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

ECMO anticoagulation and hemostasis management in the perioperative period and during procedures.

DATA EXTRACTION

Two authors reviewed all citations independently, with a third independent reviewer resolving any conflicts. Seventeen 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. 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. Four good practice statements, 7 recommendations, and 18 consensus statements are presented.

CONCLUSIONS

Although agreement among experts was strong, important future research is required in this population for evidence-informed recommendations.

Early acute kidney injury and transition to renal replacement therapy in critically ill patients with SARS-CoV-2 requiring veno-venous extracorporeal membrane oxygenation

BACKGROUND

Critically ill patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requiring veno-venous extracorporeal membrane oxygenation (vv-ECMO) are at risk for acute kidney injury (AKI). Currently, the incidence of AKI and progression to kidney replacement therapy (RRT) in critically ill patients with vv-ECMO for severe COVID-19 and implications on outcome are still unclear.

METHODS

Retrospective analysis at the University Medical Center Hamburg-Eppendorf (Germany) between March 1st, 2020 and July 31st, 2021. Demographics, clinical parameters, AKI, type of organ support, length of ICU stay, mortality and severity scores were assessed.

RESULTS

Ninety-one critically ill patients with SARS-CoV-2 requiring ECMO were included. The median age of the study population was 57 (IQR 49-64) years and 67% (n = 61) were male. The median SAPS II and SOFA Score on admission were 40 (34-46) and 12 (10-14) points, respectively. We observed that 45% (n = 41) developed early-AKI, 38% (n = 35) late-AKI and 16% (n = 15) no AKI during the ICU stay. Overall, 70% (n = 64) of patients required RRT during the ICU stay, 93% with early-AKI and 74% with late-AKI. Risk factors for early-AKI were younger age (OR 0.94, 95% CI 0.90-0.99, p = 0.02) and SAPS II (OR 1.12, 95% CI 1.06-1.19, p < 0.001). Patients with and without RRT were comparable regarding baseline characteristics. SAPS II (41 vs. 37 points, p < 0.05) and SOFA score (13 vs. 12 points, p < 0.05) on admission were significantly higher in patients receiving RRT. The median duration of ICU (36 vs. 28 days, p = 0.27) stay was longer in patients with RRT. An ICU mortality rate in patients with RRT in 69% (n = 44) and in patients without RRT of 56% (n = 27) was observed (p = 0.23).

CONCLUSION

Critically ill patients with severe SARS-CoV-2 related ARDS requiring vv-ECMO are at high risk of early acute kidney injury. Early-AKI is associated with age and severity of illness, and presents with high need for RRT. Mortality in patients with RRT was comparable to patients without RRT.

Extracorporeal membrane oxygenation and acute kidney injury: a single-center retrospective cohort

To assess the relationship between acute kidney injury (AKI) with outcomes among patients requiring extracorporeal membrane oxygenation (ECMO). This is a single-center, retrospective cohort study of adult patients admitted to intensive care units (ICU) at a tertiary referral hospital requiring ECMO from July 1, 2015, to August 30, 2019. We assessed the temporal relationship of AKI and renal replacement therapy with ECMO type (VV vs. VA). The primary outcome was in-hospital mortality rates. We used Kruskal-Wallis or chi-square tests for pairwise comparisons, cause-specific Cox proportional hazards models were utilized for the association between AKI prevalence and in-hospital mortality, and a time-dependent Cox model was used to describe the association between AKI incidence and mortality. After the screening, 190 patients met eligibility criteria [133 (70%) AKI, 81 (43%) required RRT]. The median age was 61 years, and 61% were males. Among AKI patients, 48 (36%) and 85 (64%) patients developed AKI before and after ECMO, respectively. The SOFA Day 1, baseline creatinine, respiratory rate (RR), use of vasopressin, vancomycin, proton pump inhibitor, antibiotics, duration of mechanical ventilation and ECMO, and ICU length of stay were higher in AKI patients compared with those without AKI (P < 0.01). While ICU and in-hospital mortality rates were 46% and 50%, respectively, there were no differences based on the AKI status. The type and characteristics of ECMO support were not associated with AKI risk. Among AKI patients, 77 (58%) were oliguric, and 46 (60%) of them received diuretics. Urine output in the diuretic group was only higher on the first day than in those who did not receive diuretics (P = 0.03). Among ECMO patients, AKI was not associated with increased mortality but was associated with prolonged duration of mechanical ventilation and ICU length of stay.

Neutrophil extracellular traps are increased after extracorporeal membrane oxygenation support initiation and present in thrombus: A preclinical study using sheep as an animal model

BACKGROUND

The balance between thrombosis and hemostasis is a difficult issue during extracorporeal membrane oxygenation (ECMO) support. The pathogenesis leading to thrombotic complications during ECMO support is not well understood. Neutrophil extracellular traps (NETs) were reported to participate in thrombosis and have a key role in inflammation. This study aimed to explore the role of NETs in thrombosis during ECMO support and investigate NETs as a predictive biomarker for thrombotic complications during ECMO assistance.

METHODS

Ten ovine models of ECMO support were established. Animals were then randomly divided into 2 groups (5 sheep/group): venoarterial (VA) ECMO group and venovenous (VV) ECMO group. The venous blood samples were collected at different time points. Markers of NETs were detected in plasma, neutrophils, and thrombi from the vessels and membrane. Moreover, circulating NETs levels in 8 adults treated in the intensive care unit (ICU) who received VA-ECMO and 8 healthy controls were detected; patient survival was also recorded.

RESULTS

In vivo study showed that neutrophils and NETs markers (dsDNA and citH3) levels were significantly elevated 6 h after ECMO compared to baseline. Isolated neutrophils from fresh blood at 6 h could release more NETs. dsDNA and citH3 levels were significantly higher in the VA mode than in the VV mode. NETs were found in thrombi from the vessel and membrane. Clinical data further revealed that dsDNA, citH3, and nucleosomes were higher in patients who received ECMO than in healthy controls.

CONCLUSIONS

These data suggest NETs might be associated with thrombus during ECMO support, especially in the VA mode. These findings provide new insight into preventing thrombotic complications by targeting NETs. Also, NETs may potentially become an early warning biomarker for thrombosis under ECMO assistance.

Incidence and predictors of brain infarction in neonatal patients on extracorporeal membrane oxygenation: an observational cohort study

To determine the incidence and identify predictors of brain infarctions (BI) in neonatal patients treated with extracorporeal membrane oxygenation (ECMO). We performed a retrospective cohort study at ECMO Centre Karolinska, Stockholm, Sweden. Logistic regression models were used to identify BI predictors. Neonates (age 0-28 days) treated with veno-arterial (VA) or veno-venous (VV) ECMO between 2010 and 2018. The primary outcome was a computed tomography (CT) verified BI diagnosed during ECMO treatment. In total, 223 patients were included, 102 patients (46%) underwent at least one brain CT and 27 patients (12%) were diagnosed with a BI. BI diagnosis was associated with increased 30-day mortality (48% vs. 18%). High pre-ECMO Pediatric Index of Mortality score, sepsis as the indication for ECMO treatment, VA ECMO, conversion between ECMO modes, use of continuous renal replacement therapy, and extracranial thrombosis were identified as independent predictors of BI development. The incidence of BI in neonatal ECMO patients may be higher than previously understood. Risk factor identification may help initiate steps to lower the risk or facilitate earlier diagnosis of BI in neonates undergoing ECMO treatment.

Comparison of Bivalirudin Versus Heparin for Anticoagulation During Extracorporeal Membrane Oxygenation

The effect and safety of bivalirudin compared with heparin in patients undergoing extracorporeal membrane oxygenation (ECMO) remains unclear. Therefore, we conducted a systematic review and meta-analysis to compare the effectiveness and safety of heparin and bivalirudin in patients who underwent ECMO. We searched Embase, the Cochrane Central Register of Controlled Trials, and MEDLINE. Inclusion criteria included patients (1) undergoing ECMO and (2) receiving bivalirudin or heparin. We excluded studies where the majority of patients switched heparin to bivalirudin or vice versa during the clinical course. The primary outcome was short-term mortality. We presented the results of all analyses with the use of random-effects models. Eleven studies reported short-term mortality. The use of bivalirudin was associated with significantly lower short-term mortality, compared with heparin (odds ratio: 0.71, 95% confidence interval, 0.55-0.92; p = 0.01, I2 = 7%). In this meta-analysis of observational studies, the use of bivalirudin was associated with significantly lower short-term mortality, compared with heparin. Further prospective studies are warranted to clarify this finding.

Comparison of Extracorporeal Life Support Anticoagulation Using Activated Clotting Time Only to a Multimodal Approach in Pediatric Patients

OBJECTIVE

To evaluate an institutional practice change from an extracorporeal life support (ECLS) anticoagulation monitoring strategy of activated clotting time (ACT) alone to a multimodal strategy including ACT, activated partial thrombin time, heparin anti-factor-Xa, and thromboelastography.

METHODS

This was a retrospective review of patients younger than 18 years on ECLS and heparin between January 2014 and June 2020 at a single institution.

RESULTS

Twenty-seven patients used an ACT-directed strategy and 25 used a multimodal strategy. The ACT-directed group was on ECLS for a shorter median duration than the multimodal group (136 versus 164 hours; p = 0.046). There was a non-significant increase in major hemorrhage (85.1% versus 60%; p = 0.061) and a significantly higher incidence of central nervous system (CNS) hemorrhage in the ACT-directed group (29.6% versus 0%; p = 0.004). Rates of thrombosis were similar, with a median of 3 circuit changes per group (p = 0.921). The ACT-directed group had larger median heparin doses (55 versus 34 units/kg/hr; p < 0.001), required more dose adjustments per day (3.8 versus 1.7; p < 0.001), and had higher rates of heparin doses >50 units/kg/hr (62.9% versus 16%; p = 0.001). More anticoagulation parameters were supratherapeutic (p = 0.015) and fewer were therapeutic (p < 0.001) in the ACT-directed group.

CONCLUSIONS

Patients with a multimodal strategy for monitoring anticoagulation during ECLS had lower rates of CNS hemorrhage and decreased need for large heparin doses of >50 units/kg/hr without an increase in clotting complications, compared with ACT-directed anticoagulation. Multimodal anticoagulation monitoring appears superior to ACT-only strategies and may reduce heparin exposure and risk of hemorrhagic complications for pediatric patients on ECLS.

Transcranial Doppler microemboli and acute brain injury in extracorporeal membrane oxygenation: A prospective observational study

Objective

Extracorporeal membrane oxygenation (ECMO) carries a high morbidity of acute brain injury (ABI) with resultant mortality increase. Transcranial Doppler (TCD) allows real-time characterization of regional cerebral hemodynamics, but limited data exist on the interpretation of microembolic signals (MES) in ECMO.

Methods

This prospective cohort study was conducted at a single tertiary care center, November 2017 through February 2022, and included all adult patients receiving venoarterial (VA) and venovenous (VV) ECMO undergoing TCD examinations, which all included MES monitoring.

Results

Of 145 patients on ECMO who underwent at least 1 TCD examination, 100 (68.9%) patients on VA-ECMO received 187 examinations whereas 45 (31.1%) patients on VV-ECMO received 65 examinations (P = .81). MES were observed in 35 (35.0%) patients on VA-ECMO and 2 (4.7%) patients on VV-ECMO (P < .001), corresponding to 46 (24.6%) and 2 (3.1%) TCD examinations, respectively. MES were present in 29.4% of patients on VA-ECMO without additional cardiac support, compared with 38.1% with intra-aortic balloon pump and 57.1% with left ventricular assist device, but these differences were not statistically significant (P = .39; P = .20, respectively). Presence or number of MES was not associated with VA-ECMO cannulation mode (23.4% MES presence in peripheral cannulation vs 25.8% in central cannulation, P = .80). In both VA- and VV-ECMO, MES presence or number was not associated with presence of clot or fibrin in the ECMO circuit or with any studied hemodynamic, laboratory, or ECMO parameters at the time of TCD. ABI occurred in 38% and 31.1% of patients on VA- and VV-ECMO, respectively. In multivariable logistic regression analyses, neither ABI nor a composite outcome of arterial thromboembolic events was associated with presence or number of MES in VA- ECMO.

Conclusions

TCD analysis in a large cohort of patients on ECMO demonstrates a significant number of MES, especially in patients on VA-ECMO with intra-aortic balloon pump, and/or left ventricular assist device. However, clinical associations and significance of TCD MES remain unresolved and warrant further correlation with systematic imaging and long-term neurologic follow-up.

Comparison of the Efficacy of ECMO With or Without IABP in Patients With Cardiogenic Shock: A Meta-Analysis

Objective

Studies on extracorporeal membrane oxygenation (ECMO) with and without an intra-aortic balloon pump (IABP) for cardiogenic shock (CS) have been published, but there have been no meta-analyses that compare the efficacy of these two cardiac support methods. This meta-analysis evaluated the outcomes of these two different treatment measures.

Methods

The PubMed, Embase, Cochrane Library, Web of Science, and Clinical Trials databases were searched until March 2022. Studies that were related to ECMO with or without IABP in patients with CS were screened. Quality assessments were evaluated with the methodological index for nonrandomized studies (MINORS). The primary outcome was in-hospital survival, while the secondary outcomes included duration of ECMO, duration of ICU stay, infection/sepsis, and bleeding. Revman 5.3 and STATA software were used for this meta-analysis.

Results

In total, nine manuscripts with 2,573 patients were included in the systematic review. CS patients who received ECMO in combination with IABP had significantly improved in-hospital survival compared with ECMO alone (OR = 1.58, 95% CI = 1.26–1.98, P < 0.0001). However, there were no significant differences in the duration of ECMO (MD = 0.36, 95% CI = −0.12–0.84, P = 0.14), duration of ICU stay (MD = −1.95, 95% CI = −4.05–0.15, P = 0.07), incidence of infection/sepsis (OR = 1.0, 95% CI = 0.58–1.72, P = 1.0), or bleeding (OR = 1.28, 95% CI = 0.48–3.45, P = 0.62) between the two groups of patients with CS.

Conclusion

ECMO combined with IABP can improve in-hospital survival more effectively than ECMO alone in patients with CS.

Mechanical Circulatory Support: Primer for Consultant Specialists

Mechanical life support therapies exist in many forms to temporarily replace the function of vital organs. Generally speaking, these tools are supportive therapy to allow for organ recovery but, at times, require transition to long-term mechanical support. This review will examine nonrenal extracorporeal life support for cardiac and pulmonary support as well as other mechanical circulatory support options. This is intended as a general primer and overview to assist nephrologist consultants participating in the care of these critically ill patients who often experience acute renal injury as a result of cardiopulmonary shock and from their exposure to mechanical circulatory support.

Hemostasis in Pediatric Extracorporeal Life Support: Overview and Challenges

Extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs) are increasingly used in critically ill children. Despite improvements in mechanical design and clinical management, thromboembolic and hemorrhagic events remain significant causes of morbidity and mortality related to the use of both devices. Choice of anticoagulant agents and assays for monitoring continue to present challenges in management. In this review, we describe the incidence and risk factors for thrombosis and hemorrhage, the different types of anticoagulants currently in use, the assays available for monitoring anticoagulation, and management of thromboembolic and bleeding complications in children on mechanical circulatory support (MCS). We conclude by emphasizing the areas that need further study to minimize the risk for thrombosis and hemorrhage in the use of ECMO and VAD in children.

Coagulation Dysfunction Criteria in Critically Ill Children: The PODIUM Consensus Conference

CONTEXT

Previous criteria for coagulation dysfunction in critically ill children were based mainly on expert opinion.

OBJECTIVE

To evaluate current evidence regarding coagulation tests associated with adverse outcomes in children to inform criteria for coagulation dysfunction during critical illness.

DATA SOURCES

Electronic searches of PubMed and Embase were conducted from January 1992 to January 2020 by using a combination of medical subject heading terms and text words to define concepts of coagulation dysfunction, pediatric critical illness, and outcomes of interest.

STUDY SELECTION

Studies were included if critically ill children with coagulation dysfunction were evaluated, if performance characteristics of assessment and/or scoring tools to screen for coagulation dysfunction were evaluated, and if outcomes related to mortality or functional status, organ-specific outcomes, or other patient-centered outcomes were assessed.

DATA EXTRACTION

Data were abstracted from each eligible study into a standard data extraction form, along with risk of bias assessment, by a task force member.

RESULTS

The systematic review supports the presence of at least 2 of the following criteria reflecting coagulation dysfunction in the absence of liver dysfunction: platelet count <100 000 cells per μL, international normalized ratio >1.5, fibrinogen level <150 mg/dL, and D-dimer value above 10 times the upper limit of normal, or above the assay's upper limit of detection if this limit is below 10 times the upper limit of normal.

LIMITATIONS

The proposed criteria for coagulation dysfunction are limited by the available evidence and will require future validation.

CONCLUSIONS

Validation of the proposed criteria and identified scientific priorities will enhance our understanding of coagulation dysfunction in critically ill children.

Thrombosis in Extracorporeal Membrane Oxygenation (ECMO) Circuits

Thrombosis in extracorporeal membrane oxygenation (ECMO) circuits remains a frequent complication. We characterize the location, extent, structure, and clinical implications of thrombi in 53 ECMO circuits from 46 pediatric patients. The tubing, pump, and oxygenator were examined for visible thrombi. Representative samples of thrombi were collected for histologic, immunofluorescence, and immunohistochemical analysis. Thrombi were found in 81% of ECMO circuits. The most clinically significant were inflow oxygenator membrane surface thrombi (11% of circuits), arterial tubing thrombi (30%), and venous tubing (26%) or connector thrombi (26%). Oxygenator membrane surface thrombi resulted in rapidly increasing delta pressure across the oxygenator over 1-2 days, oxygenator failure, and circuit replacement. Oxygenator membrane surface thrombi were associated with intravascular venous thrombosis and bacterial infection before starting ECMO. Arterial cannula/tubing thrombi led in one case to aortic and mesenteric artery thrombosis followed by bowel infarction. In 11% of cases, venous tubing thrombi grew large enough to break off and embolize to the pump, resulting in increased hemolysis. Antifibrinolytic therapy during ECMO was associated with an increased risk of pump thromboembolism. Other less clinically significant thrombi included pump axle thrombi with thrombus fragments trapped in the oxygenator (45%), and deep oxygenator membrane thrombi (15%). Examination of ECMO circuits after removal is a useful quality improvement tool that can elucidate the cause of circuit problems, indicate patients at increased risk of thrombosis, and suggest areas for possible improvements.

Clinical use of thrombin generation assays

Determining patient's coagulation profile, i.e. detecting a bleeding tendency or the opposite, a thrombotic risk, is crucial for clinicians in many situations. Routine coagulation assays and even more specialized tests may not allow a relevant characterization of the hemostatic balance. In contrast, thrombin generation assay (TGA) is a global assay allowing the dynamic continuous and simultaneous recording of the combined effects of both thrombin generation and thrombin inactivation. TGA thus reflects the result of procoagulant and anticoagulant activities in blood and plasma. Because of this unique feature, TGA has been widely used in a wide array of settings from both research, clinical and pharmaceutical perspectives. This includes diagnosis, prognosis, prophylaxis, and treatment of inherited and acquired bleeding and thrombotic disorders. In addition, TGA has been shown to provide relevant information for the diagnosis of coagulopathies induced by infectious diseases, comprising also disturbance of the coagulation system in COVID-19, or for the assessment of early recurrence in breast cancer. This review article aims to document most clinical applications of TGA.

Impact of CRRT in Patients with PARDS Treated with VV-ECMO

The high mortality of pediatric acute respiratory distress syndrome (PARDS) is partly related to fluid overload. Extracorporeal membrane oxygenation (ECMO) is used to treat pediatric patients with severe PARDS, but can result in acute kidney injury (AKI) and worsening fluid overload. The objective of this study was to determine whether the addition of CRRT to ECMO in patients with PARDS is associated with increased mortality. Methods: We conducted a retrospective 7-year study of patients with PARDS requiring ECMO and divided them into those requiring CRRT and those not requiring CRRT. We calculated severity of illness scores, the amount of blood products administered to both groups, and determined the impact of CRRT on mortality and morbidity. Results: We found no significant difference in severity of illness scores except the vasoactive inotropic score (VIS, 45 ± 71 vs. 139 ± 251, p = 0.042), which was significantly elevated during the initiation and the first three days of ECMO. CRRT was associated with an increase in the use of blood products and noradrenaline (p < 0.01) without changing ECMO duration, length of PICU stay or mortality. Conclusion: The addition of CRRT to ECMO is associated with a greater consumption of blood products but no increase in mortality.

Acute Brain Injury in Infant Venoarterial Extracorporeal Membrane Oxygenation: An Autopsy Study

OBJECTIVES

Characterization of the types and timing of acute brain injury in infant autopsy patients after extracorporeal membrane oxygenation.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary-care center.

PATIENTS

Infants supported on extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

Clinical and pathologic records were reviewed for infant extracorporeal membrane oxygenation patients who had undergone brain autopsy in a single center between January 2009 and December 2018. Twenty-four patients supported on venoarterial extracorporeal membrane oxygenation had postmortem examination with brain autopsy. Median age at extracorporeal membrane oxygenation initiation was 82 days (interquartile range, 11-263 d), median age at time of death was 20 weeks (interquartile range, 5-44 wk), and median extracorporeal membrane oxygenation support duration was 108 hours (interquartile range, 35-366 hr). The most common acute brain injury found at autopsy was hypoxic-ischemic brain injury (58%) followed by intracranial hemorrhage (29%). The most common types of intracranial hemorrhage were intracerebral (17%), subarachnoid (17%), and subdural (8%). Only five infants (21%) did not have acute brain injury. Correlates of acute brain injury included low preextracorporeal membrane oxygenation oxygen saturation as well as elevated liver enzymes, total bilirubin, and lactate on days 1 and 3 of extracorporeal membrane oxygenation. Gestational age, Apgar scores, birth weight, extracorporeal membrane oxygenation duration, anticoagulation therapy, and renal and hepatic impairments were not associated with acute brain injury.

CONCLUSIONS

Acute brain injury was observed in 79% of autopsies conducted in infants supported on extracorporeal membrane oxygenation. Hypoxic-ischemic brain injury was the most common type of brain injury (58%), and further associations with preextracorporeal membrane oxygenation acute brain injury require additional exploration.

Cerebral Hemodynamic Profile in Ischemic and Hemorrhagic Brain Injury Acquired During Pediatric Extracorporeal Membrane Oxygenation

OBJECTIVES

To describe the cerebral hemodynamic profiles associated with ischemic and hemorrhagic brain injury during neonatal and pediatric extracorporeal membrane oxygenation.

DESIGN

A retrospective cohort study.

SETTING

Tertiary PICU.

PATIENTS

Forty-seven neonatal and pediatric patients (0-15 yr of age) placed on extracorporeal membrane oxygenation from January 2014 to December 2018.

MEASUREMENTS AND MAIN RESULTS

Continuous monitoring of mean arterial pressure and cerebral tissue oxygen saturation was conducted through entire extracorporeal membrane oxygenation run. Wavelet analysis was performed to assess changes in cerebral autoregulation and to derive pressure-dependent autoregulation curves based on the mean arterial pressure and cerebral tissue oxygen saturation data. Patients were classified into three brain injury groups: no-injury, ischemic injury, and hemorrhagic injury based on neuroimaging results. No-injury patients (n = 23) had minimal variability in the autoregulation curve over a broad range of blood pressure. Ischemic injury (n = 16) was more common than hemorrhagic injury (n = 8), and the former was associated with increased mortality and morbidity. Ischemic group showed significant abnormalities in cerebral autoregulation in the lower blood pressure range, suggesting pressure-dependent cerebral perfusion. Hemorrhagic group had highest average blood pressure as well as the lowest cerebral tissue oxygenation saturation, suggesting elevated cerebral vascular resistance. Mean heparin dose during extracorporeal membrane oxygenation was lower in both ischemic and hemorrhagic groups compared with the no-injury group.

CONCLUSIONS

This study outlines distinct differences in underlying cerebral hemodynamics associated with ischemic and hemorrhagic brain injury acquired during extracorporeal membrane oxygenation. Real-time monitoring of cerebral hemodynamics in patients acquiring brain injury during extracorporeal membrane oxygenation can help optimize their management.

Decreased Brain Volumes and Infants With Congenital Heart Disease Undergoing Venoarterial Extracorporeal Membrane Oxygenation

OBJECTIVES

The aims of this study were to: i) determine the spectrum of brain injury and ii) compare brain volumes between pre- and postoperative brain MRI in the infants receiving extracorporeal membrane oxygenation compared with those who did not require extracorporeal membrane oxygenation.

DESIGN

Cohort study of infants with D-transposition of the great arteries or single ventricle physiology. Brain volume (cm) was measured using a segmentation of a volumetric T1-weighted gradient echo sequence. Brain imaging findings (intraventricular hemorrhage, white matter injuries, and stroke) were analyzed with respect to known clinical risk factors for brain injury and adverse neurodevelopmental outcomes. Clinical factors were collected by retrospective chart review. The association between brain volume and extracorporeal membrane oxygenation was evaluated using generalized estimating equations to account for repeated measures.

SETTING

Prospective and single-centered study.

PATIENTS

One hundred nine infants (median gestational age, 39.1 wk) with D-transposition of the great arteries (n = 77) or single ventricle physiology (n = 32) were studied pre- and postoperatively with MRI as per clinical protocol.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 28 infants (26%) receiving extracorporeal membrane oxygenation, 19 (68%) were supported with extracorporeal membrane oxygenation once, and nine (32%) were supported 2-4 times. On postoperative MRI, new white matter injury was found in only five (17%) of the extracorporeal membrane oxygenation infants versus 40 (49%) in the non-extracorporeal membrane oxygenation group (p = 0.073). The rate of stroke (9% vs 10%), intraventricular hemorrhage (24% vs 29%), and hypoxic ischemia (3% vs 14%) did not differ between the non-extracorporeal membrane oxygenation and extracorporeal membrane oxygenation groups (all p > 0.5). Accounting for D-transposition of the great arteries or single ventricle physiology diagnosis, infants requiring extracorporeal membrane oxygenation had slower brain volume with single (β = -1.67) or multiple extracorporeal membrane oxygenation runs ([β = -6.54]; overall interaction p = 0.012).

CONCLUSIONS

Patients with d-transposition of the great arteries or single ventricle physiology undergoing extracorporeal membrane oxygenation at our center have a similar incidence of brain injury but more significant impairment of perioperative brain volumes than those not requiring extracorporeal membrane oxygenation.

Effect of blood flow on platelets, leukocytes, and extracellular vesicles in thrombosis of simulated neonatal extracorporeal circulation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has frequent and sometimes lethal thrombotic complications. The role that activated platelets, leukocytes, and small (0.3-micron to 1-micron) extracellular vesicles (EVs) play in ECMO thrombosis is not well understood.

OBJECTIVES

To test the effect of blood flow rate on the generation of activated platelets, leukocytes, and EVs in a simulated neonatal ECMO circuit using heparinized human whole blood.

METHODS

Simulated neonatal roller pump circuits circulated whole blood at low, nominal, and high flow rates (0.3, 0.5, and 0.7 L/min) for 6 h. Coagulopathy was defined by thromboelastography (TEG), STA® -procoagulant phospholipid clot time (STA®- Procoag-PPL), and calibrated automated thrombogram. High-resolution flow cytometry measured the cellular expression of prothrombotic phospholipids and proteins on platelets, leukocytes, and EV.

RESULTS

Despite heparinization, occlusive thrombosis halted flow in two of five circuits at 0.3 L/min and three of five circuits at 0.7 L/min. None of the five circuits at 0.5 L/min exhibited occlusive thrombosis. Phosphatidylserine (PS)-positive platelets and EVs increased at all flow rates more than blood under static conditions (P < .0002). Tissue factor (TF)-positive leukocytes and EVs increased only in low-flow and high-flow circuits (P < .0001). Tissue factor pathway inhibitor (TFPI), at 50 times more than the concentration in healthy adults, failed to suppress thrombin initiation in low-flow and high-flow circuits.

CONCLUSIONS

This in vitro study informs ECMO specialists to avoid low and high blood flow that increases TF expression on leukocytes and EVs, which likely initiate clot formation. Interventions to decrease TF generated by ECMO may be an effective approach to decrease thrombosis.

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.

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.

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.

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.

Incidence and Impact of Acute Kidney Injury in Patients Receiving Extracorporeal Membrane Oxygenation: A Meta-Analysis

BACKGROUND

Although acute kidney injury (AKI) is a frequent complication in patients receiving extracorporeal membrane oxygenation (ECMO), the incidence and impact of AKI on mortality among patients on ECMO remain unclear. We conducted this systematic review to summarize the incidence and impact of AKI on mortality risk among adult patients on ECMO.

METHODS

A literature search was performed using EMBASE, Ovid MEDLINE, and Cochrane Databases from inception until March 2019 to identify studies assessing the incidence of AKI (using a standard AKI definition), severe AKI requiring renal replacement therapy (RRT), and the impact of AKI among adult patients on ECMO. Effect estimates from the individual studies were obtained and combined utilizing random-effects, generic inverse variance method of DerSimonian-Laird. The protocol for this systematic review is registered with PROSPERO (no. CRD42018103527).

RESULTS

41 cohort studies with a total of 10,282 adult patients receiving ECMO were enrolled. Overall, the pooled estimated incidence of AKI and severe AKI requiring RRT were 62.8% (95%CI: 52.1%-72.4%) and 44.9% (95%CI: 40.8%-49.0%), respectively. Meta-regression showed that the year of study did not significantly affect the incidence of AKI (p = 0.67) or AKI requiring RRT (p = 0.83). The pooled odds ratio (OR) of hospital mortality among patients receiving ECMO with AKI on RRT was 3.73 (95% CI, 2.87-4.85). When the analysis was limited to studies with confounder-adjusted analysis, increased hospital mortality remained significant among patients receiving ECMO with AKI requiring RRT with pooled OR of 3.32 (95% CI, 2.21-4.99). There was no publication bias as evaluated by the funnel plot and Egger's regression asymmetry test with p = 0.62 and p = 0.17 for the incidence of AKI and severe AKI requiring RRT, respectively.

CONCLUSION

Among patients receiving ECMO, the incidence rates of AKI and severe AKI requiring RRT are high, which has not changed over time. Patients who develop AKI requiring RRT while on ECMO carry 3.7-fold higher hospital mortality.

Antithrombin supplementation in adult patients receiving extracorporeal membrane oxygenation

INTRODUCTION

Extracorporeal membrane oxygenation is associated with an increased risk of thrombosis and hemorrhage. Acquired antithrombin deficiency often occurs in patients receiving extracorporeal membrane oxygenation, necessitating supplementation to restore adequate anticoagulation. Criteria for antithrombin supplementation in adult extracorporeal membrane oxygenation patients are not well defined.

METHODS

In this retrospective observational study, adult patients receiving antithrombin supplementation while supported on extracorporeal membrane oxygenation were evaluated. Antithrombin was supplemented when anti-Xa levels were subtherapeutic with unfractionated heparin infusion rates of 15-20 units/kg/h and measured antithrombin activity <50%. Patients were evaluated for changes in degree of anticoagulation and signs of bleeding 24 hours pre- and post-antithrombin supplementation.

RESULTS

A total of 14 patients received antithrombin supplementation while on extracorporeal membrane oxygenation. The median percentage of time therapeutic anti-Xa levels were maintained was 0% (0-43%) and 40% (9-84%) in the pre-antithrombin and post-antithrombin groups, respectively (p = 0.13). No difference was observed in the number of patients attaining a single therapeutic anti-Xa level (pre-antithrombin = 6, post-antithrombin = 13; p = 0.37) or unfractionated heparin infusion rate (pre-antithrombin = 7.35 (1.95-10.71) units/kg/h, post-antithrombin = 6.81 (3.45-12.58) units/kg/h; p = 0.33). Thirteen patients (92%) achieved an antithrombin activity at goal following supplementation. Antithrombin activity was maintained within goal range 52% of the time during the replacement period. Four bleeding events occurred pre-antithrombin and 10 events post-antithrombin administration (p = 0.26) with significantly more platelets administered post-antithrombin (pre-antithrombin = 0.5 units, post-antithrombin = 4.5 units; p = 0.01).

CONCLUSION

Therapeutic anticoagulation occurred more frequently following antithrombin supplementation; however, this difference was not statistically significant. More bleeding events occurred following antithrombin supplementation while observing an increase in platelet transfusions.

Routine laboratory measures of heparin anticoagulation for children on extracorporeal membrane oxygenation: Systematic review and meta-analysis

OBJECTIVE

Specific protocols for anticoagulation for children on ECMO vary across institutions, with most using a continuous infusion of unfractionated heparin. The goal of this study is to aid clinician's decision on the best measure of heparin anticoagulation test; which would be the one that correlates well with heparin activity and helps in predicting hemorrhagic and thrombotic complications.

DATA SOURCES

A comprehensive search of MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Scopus was conducted from each database's inception to 07/13/2018.

STUDY SELECTION

Studies evaluating children (<18 years) treated with ECMO and evaluating ACT, aPTT, TEG and Anti-Xa in any language were included.

DATA EXTRACTION

Two reviewers selected and appraised studies independently, and abstracted data.

RESULTS

We included 19 studies (759 patients, mean age 19.8 months). Meta-analysis showed strong correlation between heparin dosing and anti-Xa. Additionally, there was not a strong correlation between laboratory tests and complications (hemorrhagic and thrombosis), or mortality.

CONCLUSION

Based on current evidence, Anti-Xa is the only laboratory test that shows strong correlation with heparin infusion dose and seems like the most suitable test for monitoring of anticoagulation with heparin in children on ECMO.

Autopsy and clinical discrepancies in patients undergoing extracorporeal membrane oxygenation: a case series

BACKGROUND

Extracorporeal life support is used as a salvage procedure to treat refractory cardiopulmonary failure. There are limited data addressing discrepancies between pre- and postmortem findings in patients undergoing extracorporeal membrane oxygenation (ECMO). We investigated discrepancies between clinical and autopsy findings in patients placed on ECMO to assess in what proportion of patients were there significant cardiovascular or other pathologies present that were not clinically apparent prior to death.

METHODOLOGY

After institutional review board approval, a list of deceased ECMO patients who underwent autopsy examination from 2004 through 2015 was obtained from our institutional database. Retrospective analyses of findings on clinical investigations done while patients were on ECMO and findings on autopsy examination were compared and stratified according to modified Goldman Criteria, which classify discrepancies into four grades depending on their impact on patient's management and mortality.

RESULTS

Of 19 patients, 18 patients had venoarterial ECMO (9 central + 5 peripheral + 4 conversions of ECMO type) and 1 patient received venovenous ECMO. Clinically unrecognized findings were found on autopsy in all patients. 56.6% of total discrepancies found were major [class I/II; e.g., myocardial infarction (MI), intracranial bleeding]. All patients had major discrepancies (class I/II) with an average of 4.21 class I discrepancies per patient. Class I discrepancies are findings which could have altered the course of treatment and survival of the patient if recognized premortem. The most common discrepancies were cardiovascular (MI 63.2%, marked cardiac remodeling 42.1%, severe coronary disease 31.6%) in nature across four classes of discrepancies.

CONCLUSIONS

We found major discrepancies between premortem and postmortem diagnoses in patients who underwent ECMO. Our findings underscore difficulties in clinically diagnosing events on ECMO as well as the need for enhanced surveillance and better diagnostic techniques in ECMO patients. Further prospective studies are necessary to understand effects of ECMO on major organs.

Intracranial hemorrhage in neonates: A review of etiologies, patterns and predicted clinical outcomes

Intracranial hemorrhage (ICH) in neonates often results in devastating neurodevelopmental outcomes as the neonatal period is a critical window for brain development. The neurodevelopmental outcomes in neonates with ICH are determined by the maturity of the brain, the location and extent of the hemorrhage, the specific underlying etiology and the presence of other concomitant disorders. Neonatal ICH may result from various inherited and acquired disorders. We classify the etiologies of neonatal ICH into eight main categories: (1) Hemorrhagic stroke including large focal hematoma, (2) Prematurity-related hemorrhage, (3) Bleeding diathesis, (4) Genetic causes, (5) Infection, (6) Trauma-related hemorrhage, (7) Tumor-related hemorrhage and (8) Vascular malformations. Illustrative cases showing various imaging patterns that can be helpful to predict clinical outcomes will be highlighted. Potential mimics of ICH in the neonatal period are also reviewed.

Coagulation Profile Is Not a Predictor of Acute Cerebrovascular Events in Pediatric Extracorporeal Membrane Oxygenation Patients

We performed a retrospective matched case-control study evaluating whether the traditional coagulation profile predicts cerebrovascular events in children on extracorporeal membrane oxygenation (ECMO) in a 71 bed intensive care unit at a tertiary children's hospital. Between 2009 and 2014, 241 neonates and children were initiated on ECMO. The cumulative 5 year incidence of intracranial hemorrhage and infarct was 9.2% and 7.9%, respectively. Thirty-six cases were individually matched 1:1 with control subjects based on age, primary diagnosis, ECMO type, cannulation site, and the presence of pre-ECMO coagulopathy. In-hospital mortality was higher among the cases compared with control subjects (78 vs. 22%, p < 0.01). The median laboratory values that assisted with heparin anticoagulation monitoring (activated clotting time, partial thromboplastin time, and antifactor Xa) and the laboratory data that assisted with blood product administration (platelet count, prothrombin time, fibrinogen, and d-dimer) during the 24 and 72 hour periods before the cerebrovascular event did not show any significant difference between the hemorrhage group and their controls or between the infarct group and their controls. The traditional coagulation profile did not predict acute cerebrovascular events in our cohort. Other markers of neurologic injury on ECMO are yet to be elucidated. Prospective studies to determine better predictors of cerebrovascular complications in pediatric ECMO patients are required.

Anticoagulation during ECMO in neonatal and paediatric patients

Extracorporeal Membrane Oxygenation (ECMO) is a form of Extracorporeal Life Support (ECLS) which is used frequently in the paediatric and neonatal setting to support either the pulmonary, or both the pulmonary and cardiac systems. Management of ECMO requires the use of systemic anticoagulation to prevent patient and circuit based thrombosis, which in turn increases the risk of haemorrhage. A number of coagulation tests, laboratory and point of care based, are used to monitor anticoagulation, however the evidence for correlation of the test results with level of anticoagulant and clinical outcomes in children remains poor.

Principles and indications of extracorporeal life support in general thoracic surgery

The role of extracorporeal life support (ECLS) has expanded rapidly over the past 15 years to become an important tool in advanced general thoracic surgery practice. Intra-operative and in some cases continued post-operative ECLS is redefining the scope of complex surgical care. ECLS encompasses a spectrum of temporary mechanical support that may remove CO₂, oxygenate or provide hemodynamic support or a combination thereof. The most common modalities used in general thoracic surgery include extracorporeal membrane oxygenation (ECMO), interventional lung assist device (iLA^® Novalung^®, Heilbronn, Germany), and extracorporeal CO₂ removal (ECCO₂R). The ECMO and Novalung^® devices can be used in different modes for the short term or long-term support depending on the situation. In this review, the principles and current applications of ECLS in general thoracic surgery are presented.

Hematological complications in children subjected to extracorporeal membrane oxygenation

OBJECTIVES

To analyze the hematological complications and need for transfusions in children receiving extracorporeal life support (ECLS).

DESIGN

A retrospective study was carried out.

SETTING

A pediatric intensive care unit.

PATIENTS

Children under 18 years of age subjected to ECLS between September 2006 and November 2015.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Patient and ECLS characteristics, anticoagulation, hematological and coagulation parameters, transfusions and clinical course.

RESULTS

A total of 100 patients (94 with heart disease) with a median age of 11 months were studied. Seventy-six patients presented bleeding. The most frequent bleeding point was the mediastinum and 39 patients required revision surgery. In the first 3days, 97% of the patients required blood transfusion (34.4ml/kg per day), 94% platelets (21.1ml/kg per day) and 90% plasma (26.6ml/kg per day). Patients who were in the postoperative period, those who were bleeding at the start of ECLS, those requiring revision surgery, those who could not suspend extracorporeal circulation, and those subjected to transthoracic cannulation required a greater volume of transfusions than the rest of the patients. Thromboembolism occurred in 14 patients and hemolysis in 33 patients. Mortality among the children who were bleeding at the start of ECLS (57.6%) was significantly higher than in the rest of the patients (37.5%) (P=.048).

CONCLUSIONS

Children subjected to ECLS present high blood product needs. The main factors related to transfusions were the postoperative period, bleeding at the start of ECLS, revision surgery, transthoracic cannulation, and the impossibility of suspending extracorporeal circulation. Children with bleeding suffered greater mortality than the rest of the patients.

Cerebral Pathophysiology in Extracorporeal Membrane Oxygenation: Pitfalls in Daily Clinical Management

Extracorporeal membrane oxygenation (ECMO) is a life-saving technique that is widely being used in centers throughout the world. However, there is a paucity of literature surrounding the mechanisms affecting cerebral physiology while on ECMO. Studies have shown alterations in cerebral blood flow characteristics and subsequently autoregulation. Furthermore, the mechanical aspects of the ECMO circuit itself may affect cerebral circulation. The nature of these physiological/pathophysiological changes can lead to profound neurological complications. This review aims at describing the changes to normal cerebral autoregulation during ECMO, illustrating the various neuromonitoring tools available to assess markers of cerebral autoregulation, and finally discussing potential neurological complications that are associated with ECMO.

Successful Angiojet® aortic thrombectomy of extracorporeal membrane oxygenation-related thrombus in a newborn

Thrombosis and systemic embolization are important complications of extracorporeal membrane oxygenation (ECMO). We present a 2.5 kg neonate born at 37.4 weeks with hypoplastic left heart supported on ECMO that developed an acute, occlusive distal aortic thrombus that was emergently managed by transcatheter Angiojet^® (Boston Scientific, Boston, MA) thrombectomy. The procedure successfully restored perfusion to the lower extremities with sustained result upon 1-week follow-up. This case highlights the Angiojet^® thrombectomy as a treatment option for limb- or organ-threatening acute thrombus in even the most complex ECMO patients.

Anticoagulation with VADs and ECMO: walking the tightrope

The evolution of devices for mechanical circulatory support (MCS), including ventricular assist devices (VADs) for patients with heart failure and extracorporeal membrane oxygenation (ECMO) for patients with acute cardiac or respiratory failure, has improved survival for subsets of critically ill children and adults. The devices are intricate and complex, allowing blood to bypass the heart or lungs (or both). As blood flows through these artificial devices, normal hemostasis is disrupted, coagulation is promoted, and in the absence of anticoagulation, a thrombus may form in the device, resulting in device failure or embolic stroke. Therefore, anticoagulation is necessary to prevent thrombus formation and maintain device function. However, patients on MCS also have very high bleeding rates. Titrating anticoagulation to prevent hemorrhagic complications and thrombotic events can be a challenge, and hematologists may be consulted in complex cases. Substantial variability remains in the approach to anticoagulant and antiplatelet therapy for patients on MCS, largely because of the lack of high-quality data. Improvements in the design and manufacture of these devices, as well as in the individualized titration of antithrombotic intensity, are expected to enhance outcomes. Several factors pertaining to both the device and the patient (adult and children) should be considered when attempting to optimize this delicate balance.

P2Y12 Receptor Function and Response to Cangrelor in Neonates With Cyanotic Congenital Heart Disease

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Platelets from neonatal patients with cyanotic congenital heart disease have a nearly identical response to adenosine diphosphate activation and P2Y₁₂ receptor blockade with cangrelor as their adult counterparts.

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Integrating high-throughput technologies with unique biological platforms can provide considerable insight into the potential clinical use of antiplatelet agents for neonatal and pediatric patients at risk for thrombosis.

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Cangrelor may prove to be an effective antithrombotic drug with pharmacological properties well suited for use in the immediate post-operative period for neonates palliated with systemic-to-pulmonary artery shunts.

Shunt thrombosis remains a major cause of morbidity and mortality, especially during the initial palliation for single-ventricle physiology. The authors present evidence that the P2Y₁₂ inhibitor cangrelor may fill a therapeutic void in thromboprophylaxis. They base this theory on results showing that platelets from neonatal patients with cyanotic congenital heart disease have a robust response to adenosine diphosphate and are amenable to P2Y₁₂ inhibition with cangrelor. Unique to this study was their ability to establish drug efficacy in an avatar mouse model that permits the in vivo evaluation of human platelet–mediated thrombus formation illustrating that this P2Y₁₂ inhibitor yields the intended biological response.

Laboratory and clinical predictors of 30-day survival for patients on Extracorporeal Membrane Oxygenation (ECMO): 8-Year experience at Albert Einstein College of Medicine, Montefiore Medical Center

PURPOSE

Survival of patients on ECMO has remained stable in every population. Laboratory values predictors of survival are required to improve patient care.

MATERIALS AND METHODS

Clinical Looking Glass software was used to assess Electronic Medical Records (EMRs) of patients at Albert Einstein College of Medicine, Montefiore Medical Center (2007-2014).

RESULTS

Our population comprises of 166 adults and was divided in survivors and non-survivors, within 30days. Indications for ECMO were cardiac (65%), respiratory (25%) and infectious diseases (<10%). Eighty six patients (51.8%) survived the procedure. Gender, body weight, ejection fraction, diastolic blood pressure, and socio-economic status did not differ among survivors and non-survivors. In contrast, younger patients (45yo vs 55yo, p=0.0001) and higher systolic blood pressure (115mmHg vs 103mmHg, p=0.025) have favorable outcome. Univariate analysis shows that pre-cannulation values for creatinine (p=0.0003), chloride (p=0.009), bicarbonate (p=0.015) and pH (p=0.03) have prognostic value. Post-cannulation aPTT, pH, platelet and lymphocyte counts also have discriminative power. Notably, multiple logistic regressions for Multivariate Analysis identified chloride (OR 1.07; 95% CI 1.02-1.13; p=0.004), pH (OR 3.35; 95% CI 1.89-5.9; p<0.0001) and aPTT (OR 0.98; 95% CI 0.976-0.998; p=0.024) as independent risk factors for 30-day mortality. These results imply that pre-existing renal conditions and hemostatic dysregulation contribute to poor outcome. Finally, patients on VV-ECMO have increase odds of survival (OR 1.88; 95% CI 1.06-3.34; p=0.029).

CONCLUSIONS

Laboratory markers identified herein may guide the management of patients on ECMO.

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.

Current Limitations of the Assessment of Haemostasis in Adult Extracorporeal Membrane Oxygenation Patients and the Role of Point-of-Care Testing

Haemostatic perturbations are commonly seen in extracorporeal membrane oxygenation (ECMO) patients and remain a clinical challenge, contributing significantly to morbidity and mortality. The approach to anticoagulation monitoring and the management of bleeding varies considerably across ECMO centres. Routine laboratory tests have their limitations in terms of turnaround time and specificity of information provided. Newer point-of-care testing (POCT) for coagulation may overcome these issues, as it provides information about the entire coagulation pathway from clot initiation to lysis. It is also possible to obtain qualitative information on platelet function from these tests. Furthermore, the ability to incorporate these results into a goal-directed algorithm to manage bleeding with targeted transfusion strategies appears particularly attractive and cost effective. Further studies are required to evaluate the utility of POCT to optimise bleeding and anticoagulation management in these complex patients.

The Impact of Renal Failure and Renal Replacement Therapy on Outcome During Extracorporeal Membrane Oxygenation Therapy

Acute kidney injury (AKI) is common in patients treated with veno-arterial (VA-) or veno-venous (VV-) extracorporeal membrane oxygenation (ECMO). In this setting, the use of continuous renal replacement therapy (CRRT) can help to optimize fluid status but may also negatively impact on patients' outcome. In contrast, the relationship between AKI, CRRT, and survival in critically ill adult patients receiving ECMO is not well defined. The institutional ECMO database (n = 162) from November 2008 to December 2013, excluding patients with ICU survival <24 hours was reviewed. Demographics, co-morbidities, and concomitant therapies for all patients were collected. AKI was defined according to the Acute Kidney Injury Network (AKIN) criteria. ICU mortality was noted. Data were retrieved for 135 patients (79 with VA-ECMO and 56 with VV-ECMO). Of these, 95 developed AKI, 63 (47%) of whom required CRRT; thus three groups of patients were identified: (a) no AKI; (b) AKI without CRRT (AKINOCRRT ); and (c) CRRT with AKI (AKICRRT ). AKINOCCRT patients were more likely to have preexisting heart disease, to be more severely ill, and to be treated with VA-ECMO than those without AKI. AKICRRT patients were also more likely to be treated with VA-ECMO, had more organ dysfunction at the time of ECMO insertion, and needed more transfusions and inotropic agents than patients without AKI. ICU mortality was 53% (72/135) and was similar in the three groups, even when different AKI stages or VA/VV-ECMO were analyzed separately. In this study, the use of CRRT was not associated with an increased mortality in an adult population of patients treated with ECMO, even after adjustment for confounders.

The Complex Relationship of Extracorporeal Membrane Oxygenation and Acute Kidney Injury: Causation or Association?

Extracorporeal membrane oxygenation (ECMO) is a modified cardiopulmonary bypass (CPB) circuit capable of providing prolonged cardiorespiratory support. Recent advancement in ECMO technology has resulted in increased utilisation and clinical application. It can be used as a bridge-to-recovery, bridge-to-bridge, bridge-to-transplant, or bridge-to-decision. ECMO can restitute physiology in critically ill patients, which may minimise the risk of progressive multiorgan dysfunction. Alternatively, iatrogenic complications of ECMO clearly contribute to worse outcomes. These factors affect the risk : benefit ratio of ECMO which ultimately influence commencement/timing of ECMO. The complex interplay of pre-ECMO, ECMO, and post-ECMO pathophysiological processes are responsible for the substantial increased incidence of ECMO-associated acute kidney injury (EAKI). The development of EAKI significantly contributes to morbidity and mortality; however, there is a lack of evidence defining a potential benefit or causative link between ECMO and AKI. This area warrants investigation as further research will delineate the mechanisms involved and subsequent strategies to minimise the risk of EAKI. This review summarizes the current literature of ECMO and AKI, considers the possible benefits and risks of ECMO on renal function, outlines the related pathophysiology, highlights relevant investigative tools, and ultimately suggests an approach for future research into this under investigated area of critical care.

Venovenous Extracorporeal Life Support in Single-Ventricle Patients with Acute Respiratory Distress Syndrome

There is new and growing experience with venovenous extracorporeal life support (VV ECLS) for neonatal and pediatric patients with single-ventricle physiology and acute respiratory distress syndrome (ARDS). Outcomes in this population have been defined but could be improved; survival rates in single-ventricle patients on VV ECLS for respiratory failure are slightly higher than those in single-ventricle patients on venoarterial ECLS for cardiac failure (48 vs. 32-43%), but are lower than in patients with biventricular anatomy (58-74%). To that end, special consideration is necessary for patients with single-ventricle physiology who require VV ECLS for ARDS. Specifically, ARDS disrupts the balance between pulmonary and systemic blood flow through dynamic alterations in cardiopulmonary mechanics. This complexity impacts how to run the VV ECLS circuit and the transition back to conventional support. Furthermore, these patients have a complicated coagulation profile. Both venous and arterial thrombi carry marked risk in single-ventricle patients due to the vulnerability of the pulmonary, coronary, and cerebral circulations. Finally, single-ventricle palliation requires the preservation of low resistance across the pulmonary circulation, unobstructed venous return, and optimal cardiac performance including valve function. As such, the proper timing as well as the particular conduct of ECLS might differ between this population and patients without single-ventricle physiology. The goal of this review is to summarize the current state of knowledge of VV ECLS in the single-ventricle population in the context of these special considerations.

Platelet-derived microparticles generated by neonatal extracorporeal membrane oxygenation systems

Current anticoagulation strategies do not eliminate thromboembolic stroke or limb loss during neonatal extracorporeal membrane oxygenation (ECMO), a form of cardiopulmonary bypass (CPB). In adults, CPB surgery generates prothrombotic platelet-derived microparticles (PMPs), submicron membrane vesicles released from activated platelets. However, information on PMP generation in neonatal ECMO systems is lacking. The objective of this study was to compare PMP generation in five different neonatal ECMO systems, using a simulated circuit with swine blood at 300 ml/min for 4 hours. Systems were composed of both newer components (centrifugal pump and hollow-fiber oxygenator) and traditional components (roller-head pump and silicone membrane oxygenator). Free plasma hemoglobin levels were measured as an indicator of hemolysis and flow cytometry-measured PMP. Hemolysis generated in all ECMO systems was similar to that observed in noncirculated static blood (p = 0.48). There was no difference in net PMP levels between different oxygenators with a given pump. In contrast, net PMP generation in ECMO systems with a centrifugal pump was at least 2.5 times greater than in roller-head pump systems. This was significant when using either a hollow-fiber (p < 0.005) or a silicone membrane (p < 0.05) oxygenator. Future studies are needed to define the relationship between pump-generated PMP and thrombosis.

Hemorrhagic complications in pediatric cardiac patients on extracorporeal membrane oxygenation: an analysis of the Extracorporeal Life Support Organization Registry

OBJECTIVES

To determine the prevalence of and risk factors for hemorrhagic complications in children with cardiac disease requiring extracorporeal membrane oxygenation.

DESIGN

Retrospective review of the Extracorporeal Life Support Organization Registry (2002-2013).

SETTING

Participating Extracorporeal Life Support Organization centers.

PATIENTS

Patients less than 18 years old on extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 21,845 patients requiring extracorporeal membrane oxygenation during the study period, 8,905 (41%) had cardiac disease, and 79% of whom (6,995) had cardiac surgery. Hemorrhagic complications occurred in 8,480 patients (39% of overall cohort), with higher rates in cardiac versus noncardiac patients (49% vs 32%; p < 0.0001) related to cannulation and surgical site bleeding. Cardiac surgical patients had higher rates of hemorrhage compared with cardiac medical patients (57% vs 38%; p < 0.0001), and cardiac patients with hemorrhage had higher extracorporeal membrane oxygenation mortality compared with those without (42% vs 22% in medical patients and 34% vs 20% in surgical patients; both p < 0.0001). In multivariable analysis in both the cardiac medical and surgical groups, hemorrhage risk was higher in children greater than 1 year old and in patients with longer extracorporeal membrane oxygenation duration. Additional independent risk factors for hemorrhage in cardiac surgical patients included pre-extracorporeal membrane oxygenation mediastinal exploration (odds ratio, 3.6; 95% CI, 2.1-6.3), Society of Thoracic Surgeons morbidity category 4-5 (odds ratio, 1.2; 95% CI, 1.03-1.5), cannulation less than 24 hours after surgery (odds ratio, 1.6; 95% CI, 1.3-1.9), and longer cardiopulmonary bypass time (≥ 282 min [upper quartile]; odds ratio, 1.5; 95% CI, 1.3-1.9).

CONCLUSIONS

In this large, multicenter analysis, hemorrhagic complications occurred in nearly half of children with heart disease on extracorporeal membrane oxygenation and were associated with a significant mortality risk. Several factors were associated with hemorrhagic complications in cardiac surgical patients including pre-extracorporeal membrane oxygenation mediastinal exploration, greater surgical complexity, early postoperative cannulation, and longer bypass times. Whether these risks can be mitigated by modifying or delaying systemic anticoagulation requires further investigation.

Antithrombin concentrates use in children on extracorporeal membrane oxygenation: a retrospective cohort study

OBJECTIVE

To investigate whether receipt of any antithrombin concentrate improves laboratory and clinical outcomes in children undergoing extracorporeal membrane oxygenation for respiratory failure during their hospitalization compared with those who did not receive antithrombin.

DESIGN

Retrospective cohort study.

SETTING

Single, tertiary-care pediatric hospital.

PATIENTS

Sixty-four neonatal and pediatric patients who underwent extracorporeal membrane oxygenation for respiratory failure between January 2007 and September 2011.

INTERVENTION

Exposure to any antithrombin concentrate during their extracorporeal membrane oxygenation course compared with similar children who never received antithrombin concentrate.

MEASUREMENTS AND MAIN RESULTS

Thirty patients received at least one dose of antithrombin during their extracorporeal membrane oxygenation course and 34 patients did not receive any. The median age at admission was less than 1-month old. Age, duration of extracorporeal membrane oxygenation, or first antithrombin level did not differ significantly between the two cohorts. The mean plasma antithrombin level in those who never received antithrombin was 42.2% compared with 66% in those who received it. However, few levels reached the targeted antithrombin level of 120% and those who did fell back to deficient levels within an average of 6.8 hours. For those who received antithrombin concentrate, heparin infusion rates decreased by an average of 10.2 U/kg/hr for at least 12 hours following administration. No statistical differences were noted in the number of extracorporeal membrane oxygenation circuit changes, in vivo clots or hemorrhages, transfusion requirements, hospital or ICU length of stay, or in-hospital mortality.

CONCLUSIONS

Intermittent, on-demand dosing of antithrombin concentrate in pediatric patients on extracorporeal membrane oxygenation for respiratory failure increased antithrombin levels, but not typically to the targeted level. Patients who received antithrombin concentrate also had decreased heparin requirements for at least 12 hours after dosing. However, no differences were noted in the measured clinical endpoints. A prospective, randomized study of this intervention may require different dosing strategies; such a study is warranted given the unproven efficacy of this costly product.

The Influence of Free Hemoglobin and Bilirubin on Heparin Monitoring by Activated Partial Thromboplastin Time and Anti-Xa Assay

Context

Elevated free hemoglobin (Hb) and bilirubinemia complicate extracorporeal membrane oxygenation and could affect unfractionated heparin (UH) therapy monitoring by anti-Xa assay and activated partial thromboplastin time (aPTT).

Objectives

To compare in vitro response of anti-Xa and aPTT assays to UH in samples with artificial hyperbilirubinemia and hyperhemoglobinemia and to estimate if this interference is also observed in vivo in pediatric extracorporeal membrane oxygenation.

Design

Measurement of aPTT and anti-Xa activity in plasma spiked with UH and increased concentration of free Hb and/or conjugated bilirubin. All samples with anti-Xa activity, antithrombin, free Hb, and bilirubin determination and infused dose of UH from inpatients on extracorporeal membrane oxygenation were extracted from the clinical patient database and analyzed.

Results

Each increment of free Hb by 100 mg/dL significantly shortened aPTT, whereas an increment of bilirubin by 6 mg/dL caused significant prolongation of aPTT and stepwise increase of free Hb and/or bilirubin in plasma decreased anti-Xa activity by 0.03 to 0.05 IU/mL. Extracorporeal membrane oxygenation samples with free Hb 50 mg/dL or greater had significantly lower anti-Xa activity compared with normal ones: 0.33 (0.25–0.42) versus 0.4 (0.31–0.48) IU/mL (P = .01), despite the identical UH infusion and similar antithrombin activity. Moderate increase of free Hb by 59 mg/dL was associated with absolute decrease of anti-Xa activity by 0.07 IU/mL.

Conclusions

Activated partial thromboplastin time and anti-Xa assay are affected by elevated level of free Hb and/or bilirubin in the presence of UH, and lower anti-Xa activity is noted in extracorporeal membrane oxygenation patients with elevated free Hb. Severe hemolysis and/or hyperbilirubinemia could compromise UH monitoring based on these assays.