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

Priorities for Clinical Research in Pediatric Extracorporeal Membrane Oxygenation Anticoagulation From the Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To identify and prioritize research questions for anticoagulation and hemostasis management of neonates and children supported with extracorporeal membrane oxygenation (ECMO) from the Pediatric ECMO Anticoagulation CollaborativE (PEACE) consensus.

DATA SOURCES

Systematic review was performed using PubMed, EMBASE, and Cochrane Library (CENTRAL) databases from January 1988 to May 2021, followed by serial consensus conferences of international, interprofessional experts in the management of ECMO for critically ill neonates and children.

STUDY SELECTION

The management of ECMO anticoagulation for critically ill neonates and children.

DATA EXTRACTION

Within each of the eight subgroups, two authors reviewed all citations independently, with a third independent reviewer resolving any conflicts.

DATA SYNTHESIS

Following the systematic review of MEDLINE, EMBASE, and Cochrane Library databases from January 1988 to May 2021, and the consensus process for clinical recommendations and consensus statements, PEACE panel experts constructed research priorities using the Child Health and Nutrition Research Initiative methodology. Twenty research topics were prioritized, falling within five domains (definitions and outcomes, therapeutics, anticoagulant monitoring, protocolized management, and impact of the ECMO circuit and its components on hemostasis).

CONCLUSIONS

We present the research priorities identified by the PEACE expert panel after a systematic review of existing evidence informing clinical care of neonates and children managed with ECMO. More research is required within the five identified domains to ultimately inform and improve the care of this vulnerable population.

The Influence of the Extracorporeal Membrane Oxygenation Circuit and Components on Anticoagulation Management: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic-review informed, modified Delphi consensus regarding the influence of extracorporeal membrane oxygenation (ECMO) circuit components on anticoagulation practices for pediatric 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

Management of ECMO anticoagulation in the setting of different ECMO circuit components.

DATA EXTRACTION

Two authors reviewed all citations independently, with a third independent reviewer resolving conflicts. Twenty-nine references were used for data extraction and informed recommendations, evidence-based consensus statements, and good practice statements. 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 or good practice statements for the influence of ECMO circuit and components on anticoagulation management. A web-based modified Delphi process was used to build consensus via the Research And Development/University of California Appropriateness Method. Consensus was defined as greater than 80% agreement. One good practice statement, 2 weak recommendations, and 2 consensus statements are presented.

CONCLUSIONS

The incorporation of new component technologies into clinical practice has outpaced clinical investigations of anticoagulation strategies for pediatric ECMO. Future investigations should leverage academic and industrial collaborations, translational platforms, and modern biostatistical methods to improve patient outcomes.

Enteral nutrition in children and adolescents who receive extracorporeal membrane oxygenation and its impact on complications and mortality: A systematic review and meta-analysis

Enteral nutrition (EN) is one method of nutrition support for children and adolescents receiving extracorporeal membrane oxygenation (ECMO) therapy, and there are no guidelines for its use in this population. We conducted a systematic review to determine whether EN is effective and safe in children supported by ECMO. We searched the Cochrane Library database, MEDLINE, and Embase on Ovid in March 2023 to identify studies that evaluated children and adolescents who received ECMO and were treated with EN. Random effects meta-analysis was used to estimate the odds of mortality with EN compared with parenteral nutrition (PN). A total of 14 studies were included in this review with 1650 patients (796 received EN). The median duration of ECMO was 5-10 days, and the median EN initiation time ranged from 23 h to 7 days. The pooled results suggest no significant difference in mortality with EN compared with PN (odds ratio [OR] = 0.77; 95% CI, 0.56-1.05; I2 = 26%). Exclusion of the only study that reported an increase in mortality resulted in a borderline significant reduction in mortality with EN (OR = 0.71; 95% CI, 0.51-1.00; I2 = 26%). The predictors of EN were male sex, older age, heavier weight, greater height, cardiac diagnosis, longer duration of ECMO, and use of venovenous ECMO. Most studies suggest no correlation between EN and complications. EN use in children and adolescents who receive ECMO does not appear to be associated with increased mortality compared with PN and was safe in terms of intestinal complications and feeding intolerance.

Percutaneous Mechanical Circulatory Support in Acute Heart Failure Complicated with Cardiogenic Shock

Despite advancements in algorithms concerning the management of cardiogenic shock, current guidelines still lack the adequate integration of mechanical circulatory support devices. In recent years, more and more devices have been developed to provide circulatory with or without respiratory support, when conservative treatment with inotropic agents and vasopressors has failed. Mechanical circulatory support can be contemplated for patients with severe, refractory, or acute-coronary-syndrome-related cardiogenic shock. Through this narrative review, we delve into the differences among the types of currently used devices by presenting their notable advantages and inconveniences. We address the technical issues emerging while choosing the best possible device, temporarily as a bridge to another treatment plan or as a destination therapy, in the optimal timing for each type of patient. We also highlight the diverse implantation and removal techniques to avoid major complications such as bleeding and limb ischemia. Ultimately, we hope to shed some light in the gaps of evidence and the importance of conducting further organized studies around the topic of mechanical circulatory support when dealing with such a high mortality rate.

Fluid Flow Analysis of Neonatal Dual-Lumen Cannulas for Venovenous Extracorporeal Membrane Oxygenation

Hemolysis persists as a common and serious problem for neonatal patients on extracorporeal membrane oxygenation (ECMO). Since the cannula within the ECMO circuit is associated with hemolysis-inducing shear stresses, real-world internal fluid flow measurements are urgently needed to understand the mechanism and confirm computational estimates. This study appears to be the first experimental study of fluid flow inside commercial ECMO dual-lumen cannulas (DLCs) and first particle image velocimetry (PIV) visualization inside a complicated medical device. The internal geometries of four different opaque neonatal DLCs, both atrial and bicaval positioning geometries each sized 13 Fr and 16 Fr, were replicated by three-dimensional printing clear lumen scaled-up models, which were integrated in a circuit with appropriate ECMO flow parameters. PIV was then used to visualize two-dimensional fluid flow in a single cross section within the models. An empirical model accounting for shear stress and exposure time was used to compare the maximum expected level of hemolysis through each model. The maximum measured peak shear stress recorded was 16±2 Pa in the top arterial bicaval 13 Fr model. The atrial and 16 Fr cannula models never produced greater single-pass peak shear stress or hemolysis than the bicaval and 13 Fr models, respectively, and no difference was found in hemolysis at two different flow rates. After 5 days of flow, small DLC-induced hemolysis values for a single pass through each cannula were modeled to linearly accumulate and caused the most severe hemolysis in the bicaval 13 Fr DLC. Engineering and clinical solutions to improve cannula safety are proposed.

Hemolysis during Venovenous Extracorporeal Membrane Oxygenation in Neonates with Congenital Diaphragmatic Hernia: A Prospective Observational Study

OBJECTIVE

To investigate the incidence of hemolysis and its association with outcome in neonates with congenital diaphragmatic hernia (CDH) requiring venovenous extracorporeal membrane oxygenation (ECMO) treatment using a Medos Deltastream circuit with a DP3 pump, a hilite 800 LT oxygenator system, and a ¼' tubing.

STUDY DESIGN

Plasma free hemoglobin (PFH) was prospectively measured once daily during ECMO using spectrophotometric testing. Patients (n = 62) were allocated into two groups according to presence or absence of hemolysis. Hemolysis was defined as PFH ≥ 50 mg/dL on at least 2 consecutive days during ECMO treatment. Hemolysis was classified as either moderate with a maximum PFH of 50-100 mg/dL or severe with a maximum PFH >100 mg/dL.

RESULTS

Hemolysis was detected in 14 patients (22.6%). Mortality was 100% in neonates with hemolysis compared with 31.1% in neonates without hemolysis (P < .001). In 21.4% hemolysis was moderate and in 78.6% severe. Using multivariable analysis, hemolysis (hazard ratio: 6.8; 95%CI: 1.86-24.86) and suprasystemic pulmonary hypertension (PH) (hazard ratio: 3.07; 95%CI: 1.01-9.32) were independently associated with mortality. Hemolysis occurred significantly more often using 8 French (Fr) cannulae than 13 Fr cannulae (43% vs 17%; P = .039). Cutoff for relative ECMO flow to predict hemolysis were 115 ml/kg/ minute for patients with 8 Fr cannulae (Area under the curve [AUC] 0.786, P = .042) and 100 ml/kg/ minute for patients with 13 Fr cannulae (AUC 0.840, P < .001).

CONCLUSIONS

Hemolysis in CDH neonates receiving venovenous ECMO is independently associated with mortality.

Carboxyhemoglobin and Methemoglobin Levels and Hemolysis in Children Undergoing Cardiac Surgery With Cardiopulmonary Bypass

Hemolysis is a complication of cardiopulmonary bypass (CPB). Carboxyhemoglobin (COHb) and methemoglobin (MetHb) were suggested as potential hemolysis biomarkers. This retrospective study was based on a prospective registry aimed to determine the association of COHb and MetHb levels with hemolysis in pediatric patients <4 years old who underwent cardiac surgery with CPB. Plasma-free hemoglobin (PFH), COHb, and MetHb levels were measured before CPB; every 30 minutes during CPB; and on postoperative days 1, 2, and 3. Patients were classified into hemolysis and nonhemolysis groups based on the maximum PFH levels during CPB. A total of 193 patients were included. No significant difference was observed in the maximum COHb levels during CPB (COHb CPB ) between the hemolysis and nonhemolysis groups (1.2% [interquartile range {IQR} 0.9-1.4%] vs. 1.1% [IQR: 0.9-1.4%]; p = 0.17). The maximum MetHb levels during CPB (MetHb CPB ) were significantly higher in the hemolysis group than in the nonhemolysis group (1.3% [IQR: 1.1-1.5%] vs. 1.2% [IQR: 1.0-1.4%]; p = 0.007). Areas under the receiver operating curves of COHb CPB and MetHb CPB were 0.557 (95% confidence interval: 0.475-0.640) and 0.615 (95% confidence interval: 0.535-0.695), respectively. Therefore, the predictive ability of both hemolysis biomarkers during CPB is limited.

Intravascular Hemolysis and AKI in Children Undergoing Extracorporeal Membrane Oxygenation

Key Points

The incidence of AKI while undergoing ECMO in pediatric patients is high and independently increases mortality. Laboratory markers consistent with intravascular hemolysis increase the hazard of a composite outcome of AKI or RRT while undergoing ECMO. Further research into appropriate monitoring or treatment of ECMO-associated hemolysis may lead to important interventions to prevent AKI.

Background

AKI is common in patients requiring extracorporeal membrane oxygenation (ECMO), with a variety of proposed mechanisms. We sought to describe the effect of laboratory evidence of ECMO-associated intravascular hemolysis on AKI and RRT.

Methods

This retrospective cohort study included patients treated with ECMO at a single center over 10 years. The primary outcome was a composite of time to RRT or AKI (by creatinine-based Kidney Disease Improving Global Outcomes criteria) after ECMO start. Serum creatinine closest to ECMO start time was considered the pre-ECMO baseline and used to determine abnormal kidney function at ECMO start. The patient's subsequent creatinine values were used to identify AKI on ECMO. Multivariable cause-specific Cox proportional hazards models were used to assess the effect of separate markers of intravascular hemolysis on the time to the composite outcome after controlling for confounders.

Results

Five hundred and one children were evaluated with a median age 1.2 years, 56% male. Four separate multivariable models, each with a different marker of hemolysis (plasma-free hemoglobin, lactate dehydrogenase (LDH), minimum platelet count, and minimum daily hemoglobin), were used to examine the effect on the composite outcome of AKI/RRT. An elevated plasma-free hemoglobin, the most specific of these hemolysis markers, demonstrated an almost three-fold higher adjusted hazard for the composite outcome (hazard ratio [HR], 2.9; P value < 0.01; 95% confidence interval [CI], 1.4 to 5.6). Elevated LDH was associated with an adjusted HR of 3.1 (P value < 0.01; 95% CI, 1.7 to 5.5). Effect estimates were also pronounced in a composite outcome of only more severe AKI, stage 2+ AKI/RRT: HR 6.6 (P value < 0.01; 95% CI, 3.3 to 13.2) for plasma-free hemoglobin and 2.8 (P value < 0.01; 95% CI, 1.5 to 5.6) for LDH.

Conclusions

Laboratory findings consistent with intravascular hemolysis on ECMO were independently associated with a higher hazard of a composite outcome of AKI/RRT in children undergoing ECMO.

Evolution of Carboxyhemoglobin in Children Supported by Extracorporeal Membrane Oxygenation: An Observational Single-Center Study

Carboxyhemoglobin (COHb) is potentially a novel marker of hemolysis on extracorporeal membrane oxygenation (ECMO) and may be useful as an indicator for circuit-related complication in adults, but little is known about COHb levels in children. An observational single-center study was performed between January 2018 and December 2021. Fifty-eight children were included and COHb levels were obtained along with routine blood gas analysis before, during, and after ECMO support. From the 6th hour of ECMO support, the COHb level increased relative to the pre-ECMO level, with an adjusted mean difference of 0.44 (95% confidence interval [CI], 0.26-0.62; p < 0.001) and remained higher during ECMO run and within 6 hours after weaning ( p < 0.001). Among the 18 children (31%) who experienced at least one circuit-related complication leading to a circuit change, we observed a significant decrease in COHb levels within 24 hours after the circuit change, compared with the 24 hours before (adjusted mean difference, 0.54%; 95% CI, 0.27-0.80; p < 0.001). The maximal daily COHb level was able to predict circuit-related complications within 24 hours following COHb measurement with an area under the receiver operating characteristic (ROC) curve of 0.85 (95% CI, 0.77-0.92; p < 0.001).

Ex vivo hemolysis: three cases demonstrating mechanically-induced hemolysis from the extracorporeal circuit during hemodialysis

Sporadic mechanically-induced hemolysis associated with kinks in extracorporeal blood circuits during hemodialysis is a rare but potentially serious complication that exhibits laboratory features consistent with both in vivo and in vitro hemolysis. Misclassification of clinically significant hemolysis as in vitro can lead to inappropriate test cancellation and delayed medical interventions. Here, we report three cases of hemolysis attributed to kinked hemodialysis blood lines, which we have defined as "ex vivo" hemolysis. All three cases demonstrated an initial mixed picture of laboratory features consistent with both classifications of hemolysis. Specifically, absent features of in vivo hemolysis on blood film smear despite normal potassium led to the misclassification of these samples as in vitro hemolysis and their cancellation. A proposed mechanism for these overlapping laboratory features is the recirculation of damaged red blood cells from the kinked or pinched hemodialysis line back into the patient circulation producing an "ex vivo" hemolysis presentation. In two of the three cases, the patients developed acute pancreatitis as a result of hemolysis and required urgent medical follow up. We developed a decision pathway to help laboratories in identifying and handling these samples by recognizing that in vitro and in vivo hemolysis have overlapping laboratory features. These cases highlight the need for laboratorians and the clinical care team to be vigilant about mechanically-induced hemolysis from the extracorporeal circuit during hemodialysis. Communication is critical to identify the cause of hemolysis in these patients and prevent unnecessary delays in result reporting.

Causes of red blood cell loss during extracorporeal membrane oxygenation

BACKGROUND

Pediatric patients on extracorporeal membrane oxygenation (ECMO) often receive repeated red blood cell (RBC) transfusions. This study aims to quantify and characterize causes of RBC loss on ECMO.

METHODS

This retrospective, single-center, observational study includes 91 ECMO patients (age 1 day-20 years). An RBC loss index (RLI), equal to ml RBCs lost per liter of patient + circuit volume per hour, was calculated from the changes in hematocrit and transfused RBCs. To measure the contribution of RBC injury/activation, RBC extracellular vesicle (REV) generation was measured by flow cytometry.

RESULTS

Median RLI on ECMO was 1.9 ml/L/h, 13-fold higher than normal RBC production rate (0.15 ml/L/h) and equivalent to a 4.6 drop in hematocrit/day. Median RBC loss was higher in patients who died (2.95 ml/L/h) versus survived (1.70 ml/L/h, p = .0008). RLI correlated with transfusion rate (r2  = 0.71); however, transfusion rate (ml/kg) underestimated RBC loss in patients with large changes in hematocrit and over-estimated RBC loss in neonates where the circuit volume is greater than the patient blood volume. In non-bleeding patients, intravascular hemolysis represented 16% of total RBC loss and diagnostic phlebotomy 24%, suggesting that ~60% of RBC loss was due to other causes. REV generation was increased sevenfold to ninefold during ECMO.

DISCUSSION

RLI (ml/L/h) is a more reliable quantitative indicator of RBC loss than transfusion rate (ml/kg) for pediatric patients on ECMO. Phlebotomy and intravascular hemolysis only account for 40% of RBC loss in non-bleeding ECMO patients. High REV generation suggests sublethal damage and extravascular clearance may be a cause of RBC loss on ECMO.

A retrospective analysis of the hemolysis occurrence during extracorporeal membrane oxygenation in a single center

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO)-associated hemolysis still represents a serious complication. The present study aimed to investigate those predictive factors, such as flow rates, the use of anticoagulants, and circuit connected dialysis, that might play a pivotal role in hemolysis in adult patients.

METHODS

This is a retrospective single-center case series of 35 consecutive adult patients undergoing veno-venous ECMO support at our center between April 2014 and February 2020. Daily plasma-free hemoglobin (pfHb) and haptoglobin (Hpt) levels were chosen as hemolysis markers and they were analyzed along with patients' characteristics, daily laboratory findings, and corresponding ECMO system variables, as well as continuous renal replacement therapy (CRRT) when administered, looking for factors influencing their trends over time.

RESULTS

Among the many settings related to the ECMO support, the presence of CRRT connected to the ECMO circuit has been found associated with both higher daily pfHb levels and lower Hpt levels. After correction for potential confounders, hemolysis was ascribable to circuit-related variables, in particular the membrane oxygenation dead space was associated with an Hpt reduction (B = -215.307, p = 0.004). Moreover, a reduction of ECMO blood flow by 1 L/min has been associated with a daily Hpt consumption of 93.371 mg/dL (p = 0.001).

CONCLUSIONS

Technical-induced hemolysis during ECMO should be monitored not only when suspected but also during quotidian management and check-ups. While considering the clinical complexity of patients on ECMO support, clinicians should not only be aware of and anticipate possible circuitry malfunctions or inadequate flow settings, but they should also take into account the effects of an ECMO circuit-connected CRRT, as an equally important key factor triggering hemolysis.

Prevalence of hematologic complications on extracorporeal membranous oxygenation in critically ill pediatric patients: A systematic review and meta-analysis

OBJECTIVES

Despite advances in Extracorporeal Membranous Oxygenation (ECMO) equipment, hematologic complications remain significant in critically ill children. The aim of this study is to summarize prevalence of hematologic complications for children and neonates.

METHODS

MEDLINE, PubMed and Scopus databases were searched focusing on the period from January 01, 2017 to October 01, 2022. The population included critically ill children and neonates with hematologic complications. The review included all aspects of related complications including hemorrhage, thrombosis, and hemolysis. We performed random effects meta-analyses. The primary outcome measure was overall hematologic complications. Secondary outcomes are changes in the prevalence of hemorrhagic complications. Risk of bias of included studies was assessed using the Joanna Briggs Institute checklist.

RESULTS

The systematic search identified 37 studies totaling 10,659 critically ill pediatric patients receiving ECMO. The pooled prevalence of hemorrhagic complications, thrombotic complications and hemolysis among pediatric patients requiring ECMO was 43.7 % (95 % CI: 28.6 % to 58.9 %, P < 0.001), 27.6 % (95 % CI: 20.4 % to 34.8 %, P < 0.001), 34.3 % (95 % CI: 22.9 % to 45.7 %, P < 0.001). The prevalence of hemorrhagic complications was represented in descending order: surgical site (21.6 %, 95 % CI: 10.3 % to 32.9 %); cannulation site (20.6 %, 95 % CI: 11.8 % to 29.3 %); intracranial (12.2 %, 95 % CI: 9.5 % to 15.0 %); pulmonary (7.7 %, 95 % CI: 5.9 % to 9.6 %); gastrointestinal (6.0 %, 3.7 % to 8.4 %). For the assessment of thrombotic complications, thrombosis in cannulation site had a higher prevalence (28.5 %, 95 % CI: 22.1 % to 34.9 %), followed by DIC (13.5 %, 95 % CI: 8.7 % to 18.3 %) and intracranial thrombosis (4.5 %, 95 % CI: 1.4 % to 7.6 %). Predictors of increased prevalence of hemorrhagic complications included age (P = 0.017) and VV-ECMO support mode (P = 0.029).

CONCLUSIONS

Among critically ill pediatric patients, there was a series of hematologic complications can occur during ECMO support. Physicians should pay special attention to the management and establish appropriate treatment programs to reduce the occurrence of hematologic complications.

Coagulation and hemolysis complications in neonatal ECLS: Role of devices

Neonatal extracorporeal life support (ECLS) has enjoyed a long history of successful patient support for both cardiac and respiratory failure. The small size of this patient population has provided many technical challenges from cannulation to pumps and oxygenators. This is further complicated by the relatively meager commercial options for equipment owing to the relatively low utilization of neonatal ECLS compared to adults, which has exploded following the H1N1 epidemic and the availability of the polymethylpentene oxygenator. This paper focuses on the impact of equipment choices on thrombosis and hemolysis in neonatal ECLS and the underlying mechanisms behind them. Based upon the available evidence, it is clear neonatal ECLS requires careful attention to the selection and operation of all parts of the ECLS system. Practitioners should also be aware of the factors that increase blood cell fragility, which can impact decisions around equipment and subsequent operation.

Anticoagulation for Percutaneous Ventricular Assist Device-Supported Cardiogenic Shock: JACC Review Topic of the Week

Interest in the use of mechanical circulatory support for patients presenting with cardiogenic shock is growing rapidly. The Impella (Abiomed Inc), a microaxial, continuous-flow, short-term, ventricular assist device (VAD), requires meticulous postimplantation management. Because systemic anticoagulation is needed to prevent pump thrombosis, patients are exposed to increased bleeding risk, further aggravated by sepsis, thrombocytopenia, and high shear stress-induced acquired von Willebrand syndrome. The precarious balance between bleeding and thrombosis in percutaneous VAD-supported cardiogenic shock patients is often the main reason that patient outcomes are jeopardized, and there is a lack of data addressing optimal anticoagulation management strategies during percutaneous VAD support. Here, we present a parallel anti-Factor Xa/activated partial thromboplastin time-guided anticoagulation algorithm and discuss pitfalls of heparin monitoring in critically ill patients. This review will guide physicians toward a more standardized (anti)coagulation approach to tackle device-related morbidity and mortality in this critically ill patient group.

Risk factors for hemolysis with centrifugal pumps in pediatric extracorporeal membrane oxygenation: Is pump replacement an answer?

INTRODUCTION

Hemolysis during pediatric extracorporeal membrane oxygenation (ECMO) is associated with increased risk for renal failure and mortality.

OBJECTIVES

We aim to describe risk factors for hemolysis in pediatric ECMO supported by centrifugal pumps.

METHODS

We conducted an analysis of retrospective data collected at an academic children's hospital from January 2017 to December 2019.

MEASUREMENTS AND RESULTS

Plasma-free hemoglobin (PFH) levels were measured daily, and hemolysis was defined as PFH>50 mg/dL. Of 46 ECMO runs over 528 ECMO days, hemolysis occurred in 23 (58%) patients over a total of 40 (8%) ECMO days. In multivariable logistic regression models, VA-ECMO (aOR=4.69, 95% CI: 1.01-21.83) and higher hemoglobin (aOR = 1.38, 95% CI: 1.06-1.81) were independently associated with hemolysis. There were also non-significant trends toward increased risk for hemolysis with higher rotational pump speed (aOR=2.39, 95% CI: 0.75-7.65), higher packed red blood cell transfusions (aOR=1.15, 95% CI: 0.99-1.34), and higher cryoprecipitate transfusions (aOR=2.01, 95% CI: 0.83-4.86). Isolated pump exchanges that were performed in 12 patients with hemolysis led to significant decreases in PFH levels within 24 h (89 vs 11 mg/dL, p<0.01).

CONCLUSIONS

Hemolysis is common in pediatric ECMO using centrifugal pumps. Avoidance of high pump speeds and conservative administration of blood products may help to mitigate the risk for hemolysis. Furthermore, pump exchange may be an effective first-line treatment for hemolysis.

Association Between Hyperoxemia and Increased Cell-Free Plasma Hemoglobin During Cardiopulmonary Bypass in Infants and Children

OBJECTIVES

To determine potential risk factors for severe hemolysis during pediatric cardiopulmonary bypass and examine whether supraphysiologic levels of oxygen and cardiopulmonary bypass duration are associated with hemolysis.

DESIGN

Prospective observational study.

SETTING

Cardiac ICU in a university-affiliated children's hospital.

PATIENTS

Greater than 1 month to less than 18 years old patients undergoing cardiopulmonary bypass for cardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma samples from 100 patients to assess cell-free plasma hemoglobin levels were obtained at start cardiopulmonary bypass, at the end of cardiopulmonary bypass, and 2 and 24 hours after reperfusion. Arterial blood gas samples were obtained before and every 30 minutes during cardiopulmonary bypass. Patient demographics and laboratory data were collected from the electronic medical record. Plasma hemoglobin levels peaked at the end of cardiopulmonary bypass and haptoglobin levels continued to fall throughout all time points. There were 44 patients with severe hemolysis (change in cell-free plasma hemoglobin > 50 mg/dL). Younger age (odds ratio/sd 0.45 [95% CI, 0.25-0.81]) and higher mean Pao2 × cardiopulmonary bypass duration (31.11 [1.46-664.64]) were identified as risk factors for severe hemolysis in multivariable analysis. Severe hemolysis was associated with longer hospital and ICU lengths of stay as well as acute kidney injury.

CONCLUSIONS

We observed younger age and the exposure to both oxygen and duration of cardiopulmonary bypass as risk factors for hemolysis. Oxygen delivery through the cardiopulmonary bypass circuit is an easily modifiable risk factor. Its role in the production of reactive oxygen species that could alter the erythrocyte membrane deserves further examination in larger prospective studies.

Hemostasis in neonatal ECMO

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

Platelet, Red Cell, and Endothelial Activation and Injury During Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) can be lifesaving but suffers from high rates of bleeding and repeated transfusions. Current monitoring of blood cell damage during ECMO is limited to platelet counts, hematocrit, and plasma hemoglobin levels. Extracelluar vesicles (EV) are small cell fragments released when cells are activated/injured. The objective was to evaluate flow cytometric measurements of EV during ECMO as an indication of platelet, red cell, and endothelial activation/injury. Samples were collected from 55 patients (1 day to 19 years) during 58 ECMO runs. ECMO activated or injured blood cells, but the extent was highly variable and patient dependent. On average platelet activation was increased sevenfold during ECMO with up to 60-fold increased activation during the first 24 hours in some patients. EV associated with platelet and red-cell injury were increased eightfold on average but up to 200-fold in patients with disseminated intravascular coagulation, severe hemolysis, or massive transfusion. Approximately 9% of ECMO patients showed a red-cell and endothelial activation pattern that was associated with poor prognosis. Extracellular vesicles with autofluorescence similar to bilirubin appeared to come from monocytes processing hemoglobin. ECMO is associated with a highly variable, sustained increase in platelet, red-cell, and endothelial activation and injury that is a combination of circuit and transfusion related events, the patients underlying condition and possibly genetic influences on blood cell activation and injury. Extracellular vesicle measurements may improve our understanding of cellular activation and injury during ECMO as we work to improve the biocompatibility of these systems.

Carboxyhemoglobin levels in children during extracorporeal membrane oxygenation support: a retrospective study

INTRODUCTION

Hemolysis is a common complication of extracorporeal membrane oxygenation (ECMO). There are few data on whether carboxyhemoglobin (COHb), a potential marker of hemolysis, are elevated during ECMO support.

METHODS

We conducted a single-center, retrospective study comparing peak COHb levels of children pre-, during, and post-ECMO from January 2017 to August 2020.

RESULTS

There were 154 ECMO runs in 147 children (154 PICU admissions) included in the study. The median age was 3.5 (IQR 0.2, 39.2) months. Veno-arterial ECMO was the predominant mode: 146/154 (94.8%). Eighty-seven children (56.5%) underwent cardiac surgery. Peak COHb levels during ECMO were statistically significantly higher compared to pre ECMO (COHb 1.8% (IQR 1.4, 2.6) vs COHb 1.2% (IQR 0.7, 1.7), p < 0.001) and post ECMO (COHb 1.6% (IQR 1.3, 2.2), p = 0.009). Children with COHb ⩾2% were younger and had longer duration of ECMO support. Plasma hemoglobin weakly correlated with COHb level (r = 0.14; p = 0.04).

CONCLUSIONS

Carboxyhemoglobin levels increased during ECMO support compared to the pre and post ECMO period. Younger age and longer ECMO duration were associated with COHb levels ⩾2%. Plasma hemoglobin weakly correlated with COHb level.

Correlation among Hemolysis Biomarkers in Pediatric Patients Undergoing Extracorporeal Membrane Oxygenation

Hemolysis is a common complication associated with mortality on extracorporeal membrane oxygenation (ECMO). Plasma-free hemoglobin (PFH) is the most commonly used biomarker reported for hemolysis on ECMO. This test is not readily available at all institutions, and other more readily available tests may indicate hemolysis nearly as well or as well as PFH. The purpose of this study was to study the correlation of other biomarkers of hemolysis to PFH on ECMO. All patients younger than 21 years placed on ECMO in a quaternary children's hospital between January 2013 and December 2016 were included in the study; biomarkers (urine hemoglobin [U-Hb], PFH, lactate dehydrogenase [LDH], aspartate aminotransferase [AST], gross hemolysis, and red cell distribution width (RDW)) were collected from the medical record. Descriptive statistics and repeated bivariate analyses were determined using SPSS 22.0. The median age on day 0 of ECMO was 29 days (.08 years) (IQR: 2; 319 days (.005; .875 years)). The median weight was 3.9 kg (IQR: 2.8; 8.6), and the median total duration of the ECMO run was 10.48 days (IQR: 4.25; 14), with 82% of all the patients being on venoarterial ECMO. There was no correlation between hematuria on urinalysis and the level of PFH (p = .338). There was a statistically significant positive correlation between PFH and the following respective biomarkers: gross hemolysis on the routine chemistry studies (p < .01, Rho = .439), AST (p < .01, Rho = .439), RDW (p < .01, Rho = .190), LDH (p < .01, Rho = .584), and AST (when associated elevated alanine transaminase (ALT) levels were censored) (p < .01, Rho = .552). U-Hb correlated poorly with PFH. The serum biomarkers AST (in the absence of ALT elevation) and LDH can be useful surrogates for PFH to quantify hemolysis on ECMO in pediatric patients.

Centrifugal and Roller Pumps in Neonatal and Pediatric Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Analysis of Clinical Outcomes

Extracorporeal membrane oxygenation (ECMO) is an invaluable means of supporting critically ill children with refractory respiratory or cardiac failure. Controversy remains; however, whether roller or centrifugal pumps are superior, particularly in infants. We performed a comprehensive search on PubMed, Embase, and Scopus for studies comparing the use of centrifugal and roller pumps in the pediatric and neonatal population from 1973 until March 1, 2020. All prospective and retrospective comparative studies were screened. Single-arm studies and those that included adult patients were excluded. The primary endpoint was survival to discharge. Secondary endpoints were complications (mechanical, cardiac, pulmonary, neurologic, renal, and hemolytic) and requirements for inotropic support. Random effects meta-analyses across all clinical endpoints were conducted. A total of four studies with 9111 patients were included. There was a statistically significant difference in in-hospital mortality, favoring the groups where roller pumps were used. Roller pumps were associated with fewer episodes of hemolysis, mechanical complications, cardiac complications, renal complications, and less inotropic support. ECMO with roller pumps may be associated with lower mortality in children. Roller pumps were associated with fewer complications, as well as reduced hemolysis and use of inotropes.

Risk Factors for Hemolysis During Extracorporeal Life Support for Congenital Diaphragmatic Hernia

BACKGROUND

Neonates receiving extracorporeal life support (ECLS) for congenital diaphragmatic hernia (CDH) require prolonged support compared with neonates with other forms of respiratory failure. Hemolysis is a complication that can be seen during ECLS and can lead to renal failure and potentially to worse outcomes. The purpose of this study was to identify risk factors for the development of hemolysis in CDH patients treated with ECLS.

METHODS

The Extracorporeal Life Support Organization database was used to identify infants with CDH (2000-2015). The primary outcome was hemolysis (plasma-free hemoglobin >50 mg/dL). Potentially associated variables were identified in the data set. Descriptive statistics and a series of nested multivariable logistic regression models were used to identify associations between hemolysis and demographic, pre-ECLS, and on-ECLS factors.

RESULTS

There were 4576 infants with a mortality of 52.5%. The overall mean rate of hemolysis was 10.5% during the study period. In earlier years (2000-2005), the hemolysis rates were 6.3% and 52.7% for roller versus centrifugal pumps, whereas in later years (2010-2015), they were 2.9% and 26.5%, respectively. The fully adjusted model demonstrated that the use of centrifugal pumps was a strong predictor of hemolysis (odds ratio: 6.67, 95% confidence interval: 5.14-8.67). In addition, other risk factors for hemolysis included low 5-min Apgar score, on-ECLS complications (renal, metabolic, and cardiovascular), and duration of ECLS.

CONCLUSIONS

In our cohort of CDH patients receiving ECLS over 15 y, the use of centrifugal pumps increased over time, along with the rate of hemolysis. Patient- and treatment-level risk factors were identified contributing to the development of hemolysis.

ABO incompatibility and mild factor VIII deficiency in the neonate: Not too much of a problem but a challenge on ECMO

Coagulopathy and bleeding on extracorporeal membrane oxygenation (ECMO) contribute to a worse outcome, and hyperbilirubinemia is an additional threat for newborn babies. We report a case of a newborn boy with congenital diaphragmatic hernia (CDH) associated with ABO incompatibility and an inherited mild hemophilia A. Due to respiratory failure he needed ECMO on his first day of life. During ECMO an exchange transfusion was performed after an extensive hyperbilirubinemia had evolved. Thereafter severe bleeding occurred, and a very low factor VIII level was found causative for that. After factor VIII substitution bleeding was under control and the baby eventually could be weaned from ECMO, underwent corrective surgery, and recovered.

Nursing effect of ECMO combined with CRRT in the treatment of fulminant myocarditis: A protocol of randomized controlled trial

Background:

Fulminant myocarditis has a sudden onset and rapid progress, which can easily cause multiple organ failure. Acute kidney injury is a common complication. ECMO (extracorporeal membrane oxygenation) and CRRT (continuous renal replacement therapy) have been used in the treatment of fulminant myocarditis, but the combination of the 2 has an impact on the prognosis. There is still a big controversy. Therefore, the purpose of this randomized controlled trial is to evaluate the nursing effect and long-term efficacy and safety of ECMO combined with CRRT in the treatment of fulminant myocarditis.

Methods:

This is a prospective randomized controlled trial to study the effectiveness and safety of ECMO combined with CRRT in the treatment of fulminant myocarditis. Approved by the clinical research ethics committee of our hospital. Patients were randomly assigned to 1 of 2 treatment options:

Observation indicators include: basic vital signs, laboratory indicators, echocardiographic changes, complications, and outcomes. SPSS 25.0 (Chicago, IL) version statistical software package was used to analyze the data.

Discussion:

This study will evaluate the nursing effect and long-term efficacy and safety of ECMO combined with CRRT in the treatment of fulminant myocarditis. The results of this experiment will provide clinical evidence for the treatment of fulminant myocarditis with ECMO and CRRT.

Ethics and dissemination:

Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval was not required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.

OSF Registration number:

DOI 10.17605/OSF.IO/PAQBZ.

Switching to centrifugal pumps may decrease hemolysis rates among pediatric ECMO patients

Recent advances in ECLS technology have led to the adoption of centrifugal pumps for the majority of patients worldwide. Despite several advantages of centrifugal pumps, they remain controversial because a number of studies have shown increased rates of hemolysis. The aim of this study was to assess the impact of transitioning from roller to centrifugal pumps on hemolysis rates at our center. A retrospective analysis of all pediatric ECMO patients at a single center between 2005 and 2017 was undertaken. Hemolysis was defined as a plasma free hemoglobin >50 mg/dL. Multivariable logistic regression was performed correcting for several factors to determine risk factors for hemolysis and analyze outcomes among patients with hemolysis. Significant findings were those with p < 0.05. A total of 590 patients were identified during the study period. Multivariable logistic regression for risk factors for hemolysis showed roller pumps (OR 1.92, CI 1.11–3.33) and ECMO duration (OR 1.002 per hour, CI 1.00–1.01) to be significant factors. Rates of hemolysis significantly improved following conversion from roller to centrifugal pumps, with significantly lower rates of hemolysis in 2012, 2015, 2016, and 2017 when compared to the historical average with roller pumps from 2005 to 2009 (34.7%). Additionally, hemolysis was associated with an increased risk of death (OR 3.59, CI 2.05–6.29) when correcting for other factors. These data suggest decreasing rates of hemolysis with centrifugal pumps compared to roller pumps. Since hemolysis was also associated with increased risk of death, these data support the switch from roller to centrifugal pumps at ECMO centers.

Surgery in Neonatal and Pediatric ECMO Patients Other Than Congenital Diaphragmatic Hernia Repair: A 10-Year Experience

Aim of Study: The use of extracorporeal membrane oxygenation (ECMO) has increased as a result of technological developments and the expansion of indications. Relatedly, the number of patients undergoing surgery during ECMO is also rising, at least in the adult population. Little is known on surgery in children during ECMO-therapy. We therefore aimed to assess the frequencies and types of surgical interventions in neonatal and pediatric patients on ECMO and to analyze surgery-related morbidity and mortality. Methods: We retrospectively collected information of all patients on ECMO over a 10-year period in a single tertiary and designated ECMO-center, excluding patients undergoing cardiac surgery, and correction of congenital diaphragmatic hernia. Chi-squared test and Mann-Whitney U test were used to analyze data. Main Results: Thirty-two of 221 patients (14%) required surgery when on ECMO. Common interventions were thoracotomy (32%), laparotomy (23%), fasciotomy (17%), and surgical revision of ECMO (15%). Complications occurred in 28 cases (88%), resulting in a 50% in-hospital mortality rate. Surgical patients had a longer ICU stay and longer total hospital stay compared to those not receiving surgery during ECMO. No significant difference in mortality was found when comparing surgical to non-surgical patients (50 vs. 41%). Conclusions: Approximately one in seven neonatal or pediatric patients required surgical intervention during ECMO, of whom almost 90% developed a complication, resulting in a 50% mortality rate. These results should be taken into account in counseling.

Intravenous and Intraosseous Blood Transfusion With Three Different Pediatric Pressure Transfusion Strategies in an Immature Swine (Sus scrofa) Model of Hemorrhagic Shock: A Pilot Study

INTRODUCTION

Exsanguination remains the leading cause of preventable death in military conflicts, and pediatric casualties are common. Transfusion is crucial to preserve life, but vascular access is challenging in children, so intraosseous (IO) access is often required. However, the optimal transfusion method is unclear. There was therefore the need for feasibility testing of a model for contrasting the efficacy of blood infusion devices via intravenous (IV) and IO access in immature swine with bone densities similar to children.

MATERIALS AND METHODS

Eighteen immature swine (21 ± 1 kg) were bled 31% of estimated blood volume and then received autologous blood delivered by pressure bag, push-pull (PP), or LifeFlow Rapid Infuser via IO (15-gauge IO needle placed in the humeral head) or IV (auricular 20-gauge), with monitoring for 60 minutes.

RESULTS

Flow rates for LifeFlow (172 ± 28 mL/kg) were 4-fold higher than pressure bag (44 ± 13 mL/kg, P < 0.001) and 80% higher than PP (95 ± 28 mL/kg, P < 0.02). However, higher hemolysis was evident in the IV LifeFlow condition, with 6-fold more plasma-free hemoglobin than other conditions (P < 0.0001).

CONCLUSIONS

IV LifeFlow conferred higher flows, but higher hemolysis in this pilot study demonstrates the feasibility of an immature swine model toward determining optimal methods for resuscitating children with hemorrhagic shock.

Hemolysis and Plasma Free Hemoglobin During Extracorporeal Membrane Oxygenation Support: From Clinical Implications to Laboratory Details

Venovenous and venoarterial extracorporeal membrane oxygenation (ECMO) are lifesaving supports that are more and more frequently used in critically ill patients. Despite of major technological improvements observed during the last 20 years, ECMO-associated hemolysis is still a complication that may arise during such therapy. Hemolysis severity, directly appreciated by plasma free hemoglobin concentration, may be present with various intensity, from a nonalarming and tolerable hemolysis to a highly toxic one. Here, we propose a review dedicated to extracorporeal membrane oxygenation (ECMO)-associated hemolysis, with a particular emphasis on pathophysiology, prevalence, and clinical consequences of such complication. We also focus on laboratory assessment of hemolysis and on the limits that have to be known by clinicians to prevent and manage hemolytic events.

Intravascular Hemolysis and Complications During Extracorporeal Membrane Oxygenation

Venovenous and venoarterial extracorporeal membrane oxygenation (ECMO) remains a crucial lifesaving therapy for critically ill neonates with severe cardiorespiratory failure. Both the roller pump as well as the centrifugal pump are safe and efficient systems, and some red blood cell breakdown and hemolysis occurs in all ECMO systems. The roller pump functions by gravity whereas the centrifugal pump promotes the flow of blood by a magnetically driven spinning rotor to generate negative pressure. Extracorporeal Life Support Organization data indicate a significant increase in intravascular hemolysis in neonatal and pediatric patients receiving ECMO when the centrifugal pump is used compared with its use in adults. Risk factors for developing hemolysis during ECMO are small cannula size, high negative inlet pressure in the pump head, and thrombosis in the pump head and oxygenator. Excessive red blood cell breakdown and release of plasma free hemoglobin (pfHb) saturate physiologic neutralizing mechanisms such as haptoglobin and hemopexin. The increase in pro-oxidant and proinflammatory pfHb levels causes endothelial dysfunction in a dose-dependent manner. Hemolysis also increases the risk of in-hospital morbidities such as renal injury, direct hyperbilirubinemia, and thrombosis without an increase in mortality in patients receiving ECMO. Hemolysis is an unavoidable side effect of current ECMO technology and there are no approved treatments or treatment guidelines for the neonatal population. Therefore, increased vigilance, recognition of the severity of the hemolytic process, and prompt management are essential to prevent severe endothelial injury leading to proinflammatory and prothrombotic events.

Case Report First-in-Man Method Description: Left Ventricular Unloading With iVAC2L During Veno-Arterial Extracorporeal Membrane Oxygenation: From Veno-Arterial Extracorporeal Membrane Oxygenation to ECMELLA to EC-iVAC®

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is increasingly used in bi-ventricular failure with cardiogenic shock to maintain systemic perfusion. Nonetheless, it tends to increase left ventricular (LV) afterload and myocardial oxygen demand. In order to mitigate these negative effects on the myocardium, an Impella CP® (3.5 L/min Cardiac Output) can be used in conjunction with V-A ECMO (ECMELLA approach). We implemented this strategy in a patient with severe acute myocarditis complicated by cardiogenic shock. Due to a hemolysis crisis, Impella CP® had to be substituted with PulseCath iVAC2L®, which applies pulsatile flow to unload the LV. A subsequent improvement in LV systolic function was noted, with increased LV ejection fraction (LVEF), LV end-diastolic diameter (LVEDD) reduction, and a reduction in plasma free hemoglobin. This case documents the efficacy of iVAC2L in replacing Impella CP as a LV vent during V-A ECMO, with less hemolysis.

Research of flow dynamics and occlusion condition in roller pump systems used for ventricular assist

Roller pumps have been widely used in the ventricular assist field for many years, while the significant hemolysis caused by its mechanical stress is still a fundamental problem. Although the usual under-occlusion setting was considered as an effective method to reduce the hemolysis rate, its nonocclusive condition of the whole process may cause serious backflow results, which exactly places many restrictions on this method. In this study, the simulation experiments based on computational fluid dynamics (CFD) is conducted, and the occlusion angle is proposed and used to explore a more reliable adjustment form of the occlusion condition. The parameterized geometry of a roller pump is established based on the occlusion angle and other parameters. In order to simulate the motion of the roller, the dynamic mesh mode is introduced to the CFD model, and the analytic formulations used to determine the boundary position are derived. In the whole operation process of the roller pump, four feature positions of the rollers were focused and extracted, and the flow characteristics and the shear stress distribution at these positions were demonstrated. It was found that the entry and exit of the rollers could cause clear shear stress peak, especially when one roller entered, the peak got extremely high. Furthermore, the roller pumps with different occlusion angles were compared, and the results showed that decreasing the occlusion angle could lead to a notable decrease in the amplitude and range of high shear stress and the hemolysis index with a small loss of the occlusion duration. It can be concluded that appropriately decreasing the occlusion angle may be an effective method to alleviate the hemolysis which should be given more attention.

Outcomes and factors associated with early mortality in pediatric postcardiotomy veno-arterial extracorporeal membrane oxygenation

Mortality and morbidity of children received veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support after cardiac surgery remain high despite remarkable advances in medical management and devices. The purpose of this study was to describe outcomes and risk factors of applying VA-ECMO in the surgical pediatric population. We retrospectively analyzed 85 consecutive pediatric patients (aged <18 years) who received postcardiotomy VA-ECMO from January 2010 to December 2018. Median (IQR) age at ECMO implantation in this cohort was 12.7 (6.4, 43.2) months, median weight was 8.5 (6.0, 12.8) kg, mean ECMO duration was 143.2 ± 81.6 hours and mean hospital length of stay was 48.4 ± 32.4 days. Seventy-five patients (88.2%) were indicated for postcardiotomy cardiogenic shock. The successful ECMO weaning rate was 70.6% and in-hospital mortality was 52.9%. The most common diagnosis was transposition of great arteries (n = 18, 21.2%), while acute kidney injury occurred most often (n = 64, 75.3%). Multivariate logistic regression analysis showed that thrombocytopenia, hemolysis, and nosocomial infection were positively correlated with in-hospital mortality. Multivariate Cox proportional hazard regression analysis presented that thrombocytopenia significantly increased the 180-day mortality in patients with successful weaning. Therefore, multiple factors had adverse effects on prognosis. Patient selection and procedures from ECMO implantation to weaning need to be closely monitored and performed in a timely manner to improve 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.

Biomarkers of Inflammation and Lung Recovery in Extracorporeal Membrane Oxygenation Patients With Persistent Pulmonary Hypertension of the Newborn: A Feasibility Study

OBJECTIVES

Extracorporeal membrane oxygenation is a treatment for Persistent Pulmonary Hypertension of the Newborn with high mortality.

HYPOTHESIS

the extracorporeal membrane oxygenation circuit results in inflammatory responses that mitigate against successful weaning.

DESIGN

Single-center prospective observational feasibility study.

SETTING

PICU.

PATIENTS

Twenty-four neonates requiring extracorporeal membrane oxygenation support for Persistent Pulmonary Hypertension of the Newborn.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The reference outcome was death or more than 7 days of extracorporeal membrane oxygenation support. Other outcomes included serial measures of plasma-free hemoglobin and markers of its metabolism, leucocyte, platelet and endothelial activation, and biomarkers of inflammation. Of 24 participants recruited between February 2016 and June 2017, 10 died or required prolonged extracorporeal membrane oxygenation support. These patients were sicker at baseline with higher levels of plasma-free hemoglobin within 12 hours of cannulation (geometric mean ratio, 1.92; 95% CIs, 1.00-3.67; p = 0.050) but not thereafter, versus those requiring less than 7 days extracorporeal membrane oxygenation. Serum haptoglobin concentrations were significantly elevated in both groups. Patients who died or required prolonged extracorporeal membrane oxygenation support demonstrated elevated levels of platelet-leucocyte aggregation, but decreased concentrations of mediators of the inflammatory response: interleukin-8, C-reactive protein, and tumor necrosis factor α.

CONCLUSIONS

Clinical status at baseline and not levels of plasma-free hemoglobin or the systemic inflammatory response may determine the requirement for prolonged extracorporeal membrane oxygenation support in neonates.

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.

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.

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

Extracorporeal membrane oxygenation (ECMO) is a life-saving procedure that requires careful coagulation management. Indications for ECMO continue to expand, leading to more complicated patients treated by ECMO teams. At our pediatric institution, we utilize a Coagulation Team to guide anticoagulation, transfusion and hemostasis management in an effort to avoid the all-to-common complications of bleeding and thrombosis. This team formulates a coagulation plan in conjunction with a multidisciplinary ECMO team after careful review of all available laboratory data as well as the patient's clinical status. Here, we present our general strategies for ECMO management in various clinical scenarios and a review of the literature pertaining to coagulation management in the pediatric ECMO setting.

Successful Extracorporeal Membrane Oxygenation After Incidental Azygos Vein Cannulation in a Neonate With Right-Sided Congenital Diaphragmatic Hernia Interruption of the Inferior Vena Cava and Azygos Continuation

Incidental azygos vein cannulation has been reported in a few cases of neonatal extracorporeal membrane oxygenation (ECMO). This complication is described in the literature mainly in pathological conditions wherein increased central venous pressure dilates the superior vena cava (SVC), i.e., right congenital diaphragmatic hernia (CDH) or pulmonary hypertension. Azygos vein cannulation should always be suspected in cases of impaired venous return and circuit failure. Although rare, it hinders proper venous aspiration of the ECMO circuit and generally requires repositioning or replacement of the venous cannula or conversion to central cannulation. In this report, we describe a newborn with severe right CDH who required ECMO assistance, wherein incidental cannulation of the azygos vein resulted in successful functioning of the circuit because of the concomitant presence of isolated interruption of the inferior vena cava and azygos continuation. To the best of our knowledge, this is the first report of successful neonatal ECMO despite azygos vein cannulation in a patient with such rare physiology.

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.