Significance of hemolysis on extracorporeal life support after cardiac surgery in children

Urine dipstick blood and acute kidney injury in infants undergoing cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass (CPB) is associated with hemolysis and acute kidney injury (AKI). The study aim was to determine if urine dipstick blood in infants after CPB was associated with AKI and urine neutrophil gelatinase-associated lipocalin (NGAL).

METHODS

Infants who underwent CPB at a single center were enrolled prospectively between October 2017 and June 2019. Urine samples prior to CPB and 6 h after CPB cessation were analyzed in batch for NGAL and dipstick blood. AKI was defined using creatinine-based KDIGO criteria within 72 h of CPB. Spearman correlation examined associations between urine dipstick blood and NGAL at each time point. Linear regression estimated the associations between urine dipstick blood and log-transformed NGAL 6 h after CPB. Logistic regression estimated associations and compared discrimination between urine dipstick blood and NGAL for predicting AKI.

RESULTS

At baseline, 7/63 samples (11%) had > trace blood. Six hours after CPB, 62/98 samples (63%) had > trace blood and 26% had 3 + (large) blood. In total, 18/98 (18%) with a 6-h post-CPB sample had postoperative AKI. Urine dipstick blood values correlated with urine NGAL 6 h after CPB (r = 0.52, p < 0.01), but not at baseline (r = 0.06, p = 0.66). Those with 3 + (large) blood on urine dipstick had 6 times higher mean NGAL values compared to those with negative/trace blood (mean ratio 6.6, 95%CI 3.1-14.4, p < 0.01). Those with 3 + (large) blood had 8 times higher odds of AKI (OR 7.99, 95%CI 1.5-41.9, p = 0.01).

CONCLUSIONS

Urine dipstick blood post CPB may be a simple and inexpensive tool to help predict AKI in infants.

Research progress on the pathogenesis of AKI complicated by ECMO

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) stands as a pivotal intervention for patients grappling with cardiopulmonary insufficiency. However, alongside its therapeutic benefits, ECMO carries the risk of complications, with acute kidney injury (AKI) emerging as a significant concern. The precise pathophysiological underpinnings of AKI in the context of ECMO remain incompletely elucidated.

METHODS

A comprehensive literature review was conducted to explore the epidemiology and pathophysiological mechanisms underlying the utilization of ECMO in the management of AKI.

RESULTS

ECMO initiates a multifaceted cascade of inflammatory reactions, encompassing complement activation, endothelial dysfunction, white blood cell activation, and cytokine release. Furthermore, factors such as renal hypoperfusion, ischemia-reperfusion injury, hemolysis, and fluid overload exacerbate AKI. Specifically, veno-arterial ECMO (VA-ECMO) may directly induce renal hypoperfusion, whereas veno-venous ECMO (VV-ECMO) predominantly impacts pulmonary function, indirectly influencing renal function.

CONCLUSION

While ECMO offers significant therapeutic advantages, AKI persists as a potentially fatal complication. A thorough comprehension of the pathogenesis underlying ECMO-associated AKI is imperative for effective prevention and management strategies. Moreover, additional research is warranted to delineate the incidence of AKI secondary to ECMO and to refine clinical approaches accordingly.

Red Cell Damage During Extracorporeal Life Support

Sublethal damage to red blood cells (RBCs) during extracorporeal life support (ECLS) may lead to RBC loss. Using flow cytometry, phosphatidylserine-positive (PhS+) RBCs and RBC extracellular vesicles were quantified as measures of sublethal RBC injury in 41 pediatric ECLS runs, stored RBC units, and normal adult subjects. We estimated the clearance half-life of PhS+ RBCs and compared the rates of RBC loss during pediatric ECLS due to phlebotomy, intravascular hemolysis, and extravascular clearance of PhS+ RBCs. Extracorporeal life support patients had 0.9% PhS+ RBCs, sixfold higher than normal subjects (p < 0.0001). Phosphatidylserine-positive RBCs were increased in stored RBC units (twofold in whole blood derived units, p = 0.0013; 12-fold in apheresis RBC units, p < 0.0001). Phosphatidylserine-positive RBCs were cleared with an average half-life of 15 hours. During ECLS, PhS+ RBC clearance accounted for 7% of RBC loss (1-60%), phlebotomy 12%, and intravascular hemolysis 12%. Increasing PhS+ RBCs occurred in 40% of patients that died on ECLS. Red blood cell extracellular vesicles, another marker of red cell injury/activation, were elevated fivefold during ECLS. Phosphatidylserine exposure on RBCs is increased during ECLS, marking these cells for extravascular clearance with a half-life of ~15 hours and accounting for ~7% of RBC loss.

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.

Concurrent use of continuous kidney replacement therapy during extracorporeal membrane oxygenation: what pediatric nephrologists need to know-PCRRT-ICONIC practice points

Extracorporeal membrane oxygenation (ECMO) provides temporary cardiorespiratory support for neonatal, pediatric, and adult patients when traditional management has failed. This lifesaving therapy has intrinsic risks, including the development of a robust inflammatory response, acute kidney injury (AKI), fluid overload (FO), and blood loss via consumption and coagulopathy. Continuous kidney replacement therapy (CKRT) has been proposed to reduce these side effects by mitigating the host inflammatory response and controlling FO, improving outcomes in patients requiring ECMO. The Pediatric Continuous Renal Replacement Therapy (PCRRT) Workgroup and the International Collaboration of Nephrologists and Intensivists for Critical Care Children (ICONIC) met to highlight current practice standards for ECMO use within the pediatric population. This review discusses ECMO modalities, the pathophysiology of inflammation during an ECMO run, its adverse effects, various anticoagulation strategies, and the technical aspects and outcomes of implementing CKRT during ECMO in neonatal and pediatric populations. Consensus practice points and guidelines are summarized. ECMO should be utilized in patients with severe acute respiratory failure despite the use of conventional treatment modalities. The Extracorporeal Life Support Organization (ELSO) offers guidelines for ECMO initiation and management while maintaining a clinical registry of over 195,000 patients to assess outcomes and complications. Monitoring and preventing fluid overload during ECMO and CKRT are imperative to reduce mortality risk. Clinical evidence, resources, and experience of the nephrologist and healthcare team should guide the selection of ECMO circuit.

Therapeutic plasma exchange for mechanical red cell hemolysis: A case series

We present three cases of severely elevated plasma free hemoglobin (PFH) in pediatric patients on mechanical circulatory support devices at a tertiary pediatric care center. Due to severe levels of PFH in the setting of critical illness with the inability to pursue immediate mechanical device exchange, membrane filtration therapeutic plasma exchange (TPE) was performed, which resulted in a lowering of PFH levels. However, long-term outcomes were heterogeneous across the cases. This case series reviews patient presentation, organ function before and after TPE, and the overall role of TPE as an effective treatment option to decrease severely elevated PFH levels. In doing so, we hope to add to what is known about the use of TPE for mechanical red cell hemolysis and provide guidance on its use in critically ill patients.

Optimizing Outcomes in Extracorporeal Membrane Oxygenation Postcardiotomy in Pediatric Population

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

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).

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.

Effect of a standardized fluid management algorithm on acute kidney injury and mortality in pediatric patients on extracorporeal support

Acute kidney injury (AKI), fluid overload (FO), and mortality are common in pediatric patients supported by extracorporeal membrane oxygenation (ECMO). The aim of this study is to evaluate if using a fluid management algorithm reduced AKI and mortality in children supported by ECMO. We performed a retrospective study of pediatric patients aged birth to 25 years requiring ECMO at a quaternary level children's hospital from 2007 to 2019 In October 2017, a fluid management algorithm was implemented for protocolized fluid removal after deriving a daily fluid goal using a combination of diuretics and ultrafiltration. Daily algorithm compliance was defined as ≥ 12 h on the algorithm each day. The primary and secondary outcomes were AKI and mortality, respectively, and were assessed in the entire cohort and the sub-analysis of children from the era in which the algorithm was implemented. Two hundred and ninety-nine (median age 5.3 months; IQR: 0.2, 62.3; 45% male) children required ECMO (venoarterial in 85%). The fluid algorithm was applied in 74 patients. The overall AKI rate during ECMO was 38% (26% severe-stage 2/3). Both AKI incidence and mortality were significantly lower in patients managed on the algorithm (p = 0.02 and p = 0.05). After adjusting for confounders, utilization of the algorithm was associated with lower odds of AKI (aOR: 0.40, 95%CI: 0.21, 0.76; p = 0.005) but was not associated with a reduction in mortality. In the sub-analysis, algorithm compliance of 80-100% was associated with a 54% reduction in mortality (ref: < 60% compliant; aOR:0.46, 95%CI:0.22-1.00; p = 0.05).  Conclusion: Among the entire cohort, the use of a fluid management algorithm reduced the odds of AKI. Better compliance on the algorithm was associated with lower mortality. Multicenter studies that implement systematic fluid removal may represent an opportunity for improving ECMO-related outcomes. What is Known: • Acute kidney injury and fluid overload are associated with morbidity and mortality in children supported by extracorporeal membrane oxygenation. What is New: • A systematic and protocolized approach to fluid removal in children supported by extracorporeal membrane oxygenation reduces acute kidney injury incidence. • Greater adherence to a protocolized fluid removal algorithm is associated with a reduction in mortality.

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.

Safety and Effectiveness of Veno-Venous Extracorporeal Membrane Oxygenation Combined with Continuous Renal Replacement Therapy

Patients receiving extracorporeal membrane oxygenation (ECMO) often suffer from acute kidney injury (AKI), requiring continuous renal replacement therapy (CRRT). In our clinical practice, we connected the inlet line of a CRRT machine to the postoxygenator Luer port and the outlet line to the inlet Luer port of the oxygenator. In this case series, we analyzed the interaction between the two machines. Between December 31, 2017, and December 31, 2019, we enrolled 15 patients from the ICU of the San Matteo Hospital, Pavia, Italy. All of them suffered from severe acute respiratory distress syndrome and AKI stage 3. We analyzed 570 hours of CRRT combined with venovenous ECMO and collected 261,751 CRRT data. No discontinuation of CRRT occurred before 48 hours. Most of the alarms occurred within 24 hours of the connection: 22/10,831 (0.2%) showed an outranged inlet pressure, 11/10831 (0.11%) showed an outranged transmembrane pressure, 14/10,831 (0.13%) showed an outranged inlet pressure, and 138/10,831 (1.27%) an outranged effluent pressure. The rate per minute set for the ECMO circuit was correlated with the inlet (β = 5.38; CI, 95% 1.42-9.35; p = 0.008), transmembrane (β = 4.6; CI, 95% 1.97-7.24; p = 0.001), effluent (β = 3.02; CI, 95% 1.15-4.90; p = 0.002), and outlet pressures (β = 597; CI, 95% 2.31-9.63; p = 0.001) of the CRRT circuit. We reported that our configuration could be safe and effective, however well-designed studies would be beneficial for determining the potential risks and benefits.

Trends, Advantages and Disadvantages in Combined Extracorporeal Lung and Kidney Support From a Technical Point of View

Extracorporeal membrane oxygenation (ECMO) provides pulmonary and/or cardiac support for critically ill patients. Due to their diseases, they are at high risk of developing acute kidney injury. In that case, continuous renal replacement therapy (CRRT) is applied to provide renal support and fluid management. The ECMO and CRRT circuits can be combined by an integrated or parallel approach. So far, all methods used for combined extracorporeal lung and kidney support present serious drawbacks. This includes not only high risks of circuit related complications such as bleeding, thrombus formation, and hemolysis, but also increase in technical workload and health care costs. In this sense, the development of a novel optimized artificial lung device with integrated renal support could offer important treatment benefits. Therefore, we conducted a review to provide technical background on existing techniques for extracorporeal lung and kidney support and give insight on important aspects to be addressed in the development of this novel highly integrated artificial lung device.

Creatinine correction to account for fluid overload in children with acute respiratory distress syndrome treated with extracorporeal membrane oxygenation: an initial exploratory report

BACKGROUND

Creatinine is distributed between the intracellular and extracellular compartments, and as a result, the measurement of its concentration is strongly related to the fluid status of the patient. An interest has been shown in correcting measured serum creatinine levels according to the fluid balance in order to better specify the degree of acute kidney injury (AKI).

METHODS

We conducted a retrospective observational study of 33 children, aged 0 to 5 years, admitted to the pediatric intensive care unit for acute respiratory distress syndrome treated by extracorporeal membrane oxygenation. We compared measured and corrected creatinine and assessed the degree of agreement between these values using both Cohen's kappa and Krippendorff's alpha coefficient.

RESULTS

In our cohort, 37% of the classifications made according to measured creatinine levels were erroneous and, in the majority of cases, the degree of AKI was underestimated.

CONCLUSION

Correction of the measured creatinine value according to the degree of fluid overload may result in more accurate diagnosis of AKI. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

2021 ELSO Adult and Pediatric Anticoagulation Guidelines

DISCLAIMER

These guidelines for adult and pediatric anticoagulation for extracorporeal membrane oxygenation are intended for educational use to build the knowledge of physicians and other health professionals in assessing the conditions and managing the treatment of patients undergoing ECLS / ECMO and describe what are believed to be useful and safe practice for extracorporeal life support (ECLS, ECMO) but these are not necessarily consensus recommendations. The aim of clinical guidelines are to help clinicians to make informed decisions about their patients. However, adherence to a guideline does not guarantee a successful outcome. Ultimately, healthcare professionals must make their own treatment decisions about care on a case-by-case basis, after consultation with their patients, using their clinical judgment, knowledge and expertise. These guidelines do not take the place of physicians' and other health professionals' judgment in diagnosing and treatment of particular patients. These guidelines are not intended to and should not be interpreted as setting a standard of care or be deemed inclusive of all proper methods of care nor exclusive of other methods of care reasonably directed to obtaining the same results. The ultimate judgment must be made by the physician and other health professionals and the patient in light of all the circumstances presented by the individual patient, and the known variability and biological behavior of the clinical condition. These guidelines reflect the data at the time the guidelines were prepared; the results of subsequent studies or other information may cause revisions to the recommendations in these guidelines to be prudent to reflect new data, but ELSO is under no obligation to provide updates. In no event will ELSO be liable for any decision made or action taken in reliance upon the information provided through these guidelines.

Acute Kidney Injury and Extracorporeal Membrane Oxygenation: Review on Multiple Organ Support Options

Extracorporeal membrane oxygenation (ECMO) is a temporary life support system used to assist patients with life-threatening severe cardiac and/or respiratory insufficiency. Patients requiring ECMO can be considered the sickest patients admitted to the intensive care unit (ICU). Acute kidney injury (AKI) represents a frequent complication during ECMO, affecting up to 70% of patients, with multifactorial pathophysiology and an independent risk factor for mortality. Severe AKI requiring Continuous Renal Replacement Therapy (CRRT) occurs in 20% of ECMO patients, but multiple indications and different timing may imply a significantly higher application rate in different centers. CRRT can be run in parallel to ECMO through different vascular access, or it can be conducted in series by connecting the circuits. Anticoagulation of ECMO is typically managed with systemic heparin, but several approaches can be applied for the CRRT circuit, from no anticoagulation to the addition of intra-filter heparin or regional citrate anticoagulation. The combination of CRRT and ECMO can be considered a form of multiple organ support therapy, but this approach still requires optimization in timing, set-up, anticoagulation, prescription and delivery. The aim of this report is to review the pathophysiology of AKI, the CRRT delivery, anticoagulation strategies and outcomes of patients with AKI treated with ECMO.

Clearance of severely elevated plasma free hemoglobin with total plasma exchange in a pediatric ECMO patient

Extracorporeal membrane oxygenation (ECMO)-related hemolysis is common with reported incidence of 5%-18%. Plasma free hemoglobin (PFH) levels are used as a marker for hemolysis and elevated PFH is associated with acute kidney injury (AKI). Limited literature exists regarding treatment of severe hemolysis and clearance of PFH. We report 8-year-old male child on VA ECMO with severe hemolysis (PFH 895 mg/dL) and worsening AKI showing significant improvement in PFH after single volume exchange plasmapheresis with Fresh Frozen Plasma (FFP) performed in tandem via ECMO circuit.

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.

Continuous renal replacement therapy in patients treated with extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a life‐saving therapy utilized for patients with severe life‐threatening cardiorespiratory failure. Patients treated with ECMO are among the most severely ill encountered in critical care and are at high‐risk of developing multiple organ dysfunction, including acute kidney injury (AKI) and fluid overload. Continuous renal replacement therapy (CRRT) is increasingly utilized inpatients on ECMO to manage AKI and treat fluid overload. The indications for renal replacement therapy for patients on ECMO are similar to those of other critically ill populations; however, there is wide practice variation in how renal supportive therapies are utilized during ECMO. For patients requiring both CRRT and ECMO, CRRT may be connected directly to the ECMO circuit, or CRRT and ECMO may be performed independently. This review will summarize current knowledge of the epidemiology of AKI, indications and timing of CRRT, delivery of CRRT, and the outcomes of patients requiring CRRT with ECMO.

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.

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.

Extracorporeal Membrane Oxygenation and Continuous Kidney Replacement Therapy: Technology and Outcomes - A Narrative Review

The number of patients using critical care is increasing as our populations live longer thanks to advances in medical therapies. This is reflected by an increase in both usage and number of critical care beds as compared with total hospital beds across the United States. As this aging population suffers more and more from multiorgan dysfunction, including but not limited to respiratory failure, cardiac failure, and acute kidney injury, technologies are used to facilitate recovery in those that would have assuredly passed away years ago. Some of these advancements include extracorporeal membrane oxygenation and continuous kidney replacement therapy. In this article, we review the literature regarding the history, technology, indications, and outcomes of synchronous extracorporeal membrane oxygenation and kidney replacement therapy.

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.

Hemolysis and methemoglobinemia in a child with left ventricular assist Levitronix PediMag

A 5-month-old male was treated with left ventricular assist device due to cardiac failure secondary to dilated cardiomyopathy. The patient developed acute severe intravascular hemolysis with methemoglobinemia and renal failure, related to a mechanical problem due to pump cylinder misalignment. Secondary severe methemoglobinemia has not been previously described in patients undergoing ventricular assist device. Early detection of the signs and symptoms of hemolysis is crucial to prevent further complications.

Factors associated with hemolysis during extracorporeal membrane oxygenation (ECMO)-Comparison of VA- versus VV ECMO

Venovenous (VV) and venoarterial (VA) extracorporeal membrane oxygenation (ECMO) are effective support modalities to treat critically ill patients. ECMO-associated hemolysis remains a serious complication. The aim was to disclose similarities and differences in VA- and VV ECMO-associated hemolysis. This is a retrospective single-center analysis (January 2012 to September 2018) including 1,063 adult consecutive patients (VA, n = 606; VV, n = 457). Severe hemolysis (free plasma hemoglobin, fHb > 500 mg/l) during therapy occurred in 4% (VA) and 2% (VV) (p≤0.001). VV ECMO showed significantly more hemolysis by pump head thrombosis (PHT) compared to VA ECMO (9% vs. 2%; p≤0.001). Pretreatments (ECPR, cardiac surgery) of patients who required VA ECMO caused high fHb pre levels which aggravates the proof of ECMO-induced hemolysis (median (interquartile range), VA: fHb pre: 225.0 (89.3–458.0); VV: fHb pre: 72.0 (42.0–138.0); p≤0.001). The survival rate to discharge from hospital differed depending on ECMO type (40% (VA) vs. 63% (VV); p≤0.001). Hemolysis was dominant in VA ECMO patients, mainly caused by different indications and not by the ECMO support itself. PHT was the most severe form of ECMO-induced hemolysis that occurs in both therapies with low frequency, but more commonly in VV ECMO due to prolonged support time.

Acute Kidney Injury in Pediatric Patients on Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-analysis

Background: Acute kidney injury (AKI) is a well-established complication of extra-corporal membrane oxygenation (ECMO) in the adult population. The data in the pediatric and neonatal population is still limited. Moreover, the mortality risk of AKI among pediatric patients requiring ECMO remains unclear. Thus, this meta-analysis aims to assess the incidence of AKI, AKI requiring renal replacement therapy and AKI associated mortality in pediatric/neonatal patients requiring ECMO. Methods: A literature search was performed utilizing MEDLINE, EMBASE, and the Cochrane Database from inception through June 2019. We included studies that evaluated the incidence of AKI, severe AKI requiring renal replacement therapy (RRT) and the risk of mortality among pediatric patients on ECMO with AKI. Random-effects meta-analysis was used to calculate the pooled incidence of AKI and the odds ratios (OR) for mortality. Results: 13 studies with 3523 pediatric patients on ECMO were identified. Pooled incidence of AKI and AKI requiring RRT were 61.9% (95% confidence interval (CI): 39.0-80.4%) and 40.9% (95%CI: 31.2-51.4%), respectively. A meta-analysis limited to studies with standard AKI definitions showed a pooled estimated AKI incidence of 69.2% (95%CI: 59.7-77.3%). Compared with patients without AKI, those with AKI and AKI requiring RRT while on ECMO were associated with increased hospital mortality ORs of 1.70 (95% CI, 1.38-2.10) and 3.64 (95% CI: 2.02-6.55), respectively. Conclusions: The estimated incidence of AKI and severe AKI requiring RRT in pediatric patients receiving ECMO are high at 61.9% and 40.9%, respectively. AKI among pediatric patients on ECMO is significantly associated with reduced patient survival.

Automated and cost-efficient early detection of hemolysis in patients with extracorporeal life support: Use of the hemolysis-index of routine clinical chemistry platforms

PURPOSE

Patients with extracorporeal life support (ECLS) are at risk for hemolysis-related complications. Therefore, monitoring of free hemoglobin (fHb) levels is indicated. Conventional methods for fHb are laborious and not always available. Here we evaluated the suitability of the hemolysis-index (H-index), an internal quality control parameter of clinical chemistry platforms, as a clinical parameter for ECLS patients.

MATERIALS AND METHODS

The performance of the H-index assay was evaluated using standard procedures. Furthermore, H-index data from ECLS patients (n = 56) was analyzed retrospectively.

RESULTS

The H-index significantly correlated with fHb and showed good analytical performance. During ECLS 19.6% of the patients had an H-index above 20 in at least 2 consecutive blood draws, indicating significant hemolysis. In the patients with clot formation in the pumphead the H-index peaked above 100. Visible clots at other locations did not always coincide with hemolysis. H-index peaks were more prevalent in patients that died during ECLS support.

CONCLUSIONS

We conclude that the H-index is a suitable and cost-efficient alternative for the conventional fHb analysis with good analytic performance. The H-index aids in the early detection of hemolysis in patients with ECLS. A repeated H-index>20 was a predictor of mortality.

Retrospective study on the effects of the prognosis of patients treated with extracorporeal membrane oxygenation combined with continuous renal replacement therapy

Background

Patients undergoing extracorporeal membrane oxygenation (ECMO) treatment often have severe fluid overload and electrolyte imbalances and may even suffer acute kidney injury (AKI). It is often necessary to use continuous renal replacement therapy (CRRT). In this study, we aimed to retrospectively analyze the prognosis of patients treated with ECMO combined with CRRT and to find the independent factors that affect the survival rate.

Methods

There were 32 patients who were treated with ECMO combined with CRRT in our hospital from January 2007 to December 2017 who were analyzed. All of the patients were divided into a survival group and death group. The clinical indicators and biochemical indexes of the two groups were observed, and their differences were compared. Multivariate logistic regression analysis was carried out to determine the independent risk factors.

Results

The fluid balance at ECMO day 3, SOFA score and lactate at CRRT initiation, sequential organ failure assessment (SOFA) score at ECMO weaning, CRRT duration, ECMO to CRRT interval, mechanical ventilation (MV) duration, length of ICU, and overall hospital length of stay were statistically significant (P<0.05). The clinical biochemical indexes at CRRT initiation and ECMO weaning [serum creatinine, pH, white blood cell (WBC), hemoglobin (Hb), bilirubin]; patient's age, gender and BMI; and the fluid balance at ECMO days 1 and 7 were not statistically significance (P>0.05). The fluid balance at ECMO day 3 and lactate at CRRT initiation by multivariable logistic regression analysis were independent risk factors affecting patient prognosis.

Conclusions

The fluid balance at ECMO day 3 and lactate at CRRT initiation are the prognosis independent risk factors for ECMO + CRRT patients.

Comprehensive Management Considerations of Select Noncardiac Organ Systems in the Cardiac Intensive Care Unit

As the acuity and complexity of pediatric patients with congenital cardiac disease have increased, there are many noncardiac issues that may be present in these patients. These noncardiac problems may affect clinical outcomes in the cardiac intensive care unit and must be recognized and managed. The Pediatric Cardiac Intensive Care Society sought to provide an expert review of some of the most common challenges of the respiratory, gastrointestinal, hematological, renal, and endocrine systems in pediatric cardiac patients. This review provides a brief overview of literature available and common practices.

An Analysis of Risk Factors for Hemolysis in Children on Extracorporeal Membrane Oxygenation

OBJECTIVES

Hemolysis is a known complication of pediatric extracorporeal membrane oxygenation associated with renal failure and mortality. We sought to identify predictors of hemolysis in pediatric extracorporeal membrane oxygenation patients and determine its influence on outcomes.

DESIGN

Retrospective, single-center study.

SETTING

Urban, quaternary care center pediatric and neonatal ICU.

PATIENTS

Ninety-six patients requiring extracorporeal membrane oxygenation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Daily measurements of plasma-free hemoglobin were obtained while patients were on extracorporeal membrane oxygenation. Patients with a prior extracorporeal membrane oxygenation run, on extracorporeal membrane oxygenation for less than 24 hours, or without complete medical records were excluded from the study. Ninety-six patients met inclusion criteria, of which, 25 patients (26%) had plasma-free hemoglobin greater than 30 mg/dL. Of those patients, 15 of 25(60%) had plasma-free hemoglobin greater than 50 mg/dL, and 21 of 25(84%) occurred during the first 7 days on extracorporeal membrane oxygenation. Compared with patients without hemolysis, those with hemolysis were younger (0.2 mo [0.06-3.2 mo] vs 8.2 mo [0.6-86 mo]; p < 0.001), had a higher pericannulation international normalized ratio (3.9 [3.5-5.5] vs 2.6 [1.8-3.7]; p = 0.003), lower pericannulation platelet count (33 × 10/μL [22-42 × 10/μL] vs 61 × 10/μL [38-86 × 10/μL]; p < 0.001), and had a less negative inlet pressure (-3.5 mm Hg [-14 to 11.5 mm Hg] vs -19 mm Hg [-47 to 0 mm Hg]; p = 0.01). A greater proportion of patients with hemolysis had a heparin assay less than 0.2 mg/dL (50% vs 17%; p = 0.001) and had fluid removal via slow continuous ultrafiltration (32% vs 6%; p < 0.001). Patients with hemolysis had increased risk of in-hospital mortality (odds ratio 10.0; 95% CI 3.4-32; p < 0.001). On multivariable analysis, continuous ultrafiltration (odds ratio, 8.0; 95% CI, 1.9-42; p = 0.007) and pericannulation international normalized ratio greater than 3.5 (odds ratio, 7.2; 95% CI, 2.3-26; p = 0.001) were significantly associated with hemolysis.

CONCLUSIONS

Hemolysis is a common complication of pediatric extracorporeal membrane oxygenation. We found that patients with hemolysis (plasma-free hemoglobin > 30 mg/dL) had a 10-fold increase in in-hospital mortality. In our study cohort, hemolysis was associated with continuous ultrafiltration use, but not continuous renal replacement therapy. Additionally, our results suggest that the degree of coagulopathy (international normalized ratio > 3.5) at the time of cannulation influences hemolysis. Additional prospective studies are necessary to define further strategies to prevent hemolysis and improve outcomes in pediatric extracorporeal membrane oxygenation patients.

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

OBJECTIVES

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

DESIGN

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

SETTING

Three Collaborative Pediatric Critical Care Research Network-affiliated hospitals.

PATIENTS

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

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSIONS

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

Adjunctive Therapies During Extracorporeal Membrane Oxygenation to Enhance Multiple Organ Support in Critically Ill Children

Since the advent of extracorporeal membrane oxygenation (ECMO) over 40 years ago, there has been increasing interest in the use of the extracorporeal circuit as a platform for providing multiple organ support. In this review, we will examine the evidence for the use of continuous renal replacement therapy, therapeutic plasma exchange, leukopheresis, adsorptive therapies, and extracorporeal liver support in conjunction with ECMO.

Centrifugal pumps and hemolysis in pediatric extracorporeal membrane oxygenation (ECMO) patients: An analysis of Extracorporeal Life Support Organization (ELSO) registry data

PURPOSE

It is currently unclear whether centrifugal pumps cause more hemolysis than roller pumps in extracorporeal membrane oxygenation (ECMO) circuits. The aim of this study was to help answer that question in pediatric patients.

METHODS

A limited deidentified data set was extracted from the international multicenter Extracorporeal Life Support Organization (ELSO) registry comprising all reported ECMO runs for patients 18years or younger between 2010 and 2015. Logistic regression was used to evaluate a possible association between hemolysis and pump type, controlling for patient demographics, circuit factors, and complications.

RESULTS

14,776 ECMO runs for 14,026 patients had pump type recorded. Centrifugal pumps were employed in 60.4% of ECMO circuits. Hemolysis was a reported complication for 1272 (14%) centrifugal pump runs and for 291 (5%) roller pump runs. 1755 (20%) centrifugal pump runs reported kidney injury as compared to 797 (14%) roller pump runs. In the full logistic regression, the odds of hemolysis were significantly greater for runs using centrifugal pumps (OR 3.3, 95% CI 2.9-3.8, p<0.001).

CONCLUSIONS

In this retrospective analysis of a large international data set, the use of centrifugal pumps was associated with increased rates of hemolysis, hyperbilirubinemia, and kidney injury.

TYPE OF STUDY

Retrospective cohort study.

LEVEL OF EVIDENCE

Level III.

Venovenous extracorporeal membrane oxygenation for ARDS: outcome analysis of a Croatian referral center for respiratory ECMO

BACKGROUND

The use of venovenous extracorporeal membrane oxygenation (VV-ECMO) as a rescue therapy in severe acute respiratory distress syndrome (ARDS) has become well established; however, the affirmation of evidence on VV-ECMO application and the analysis of patient outcomes after VV-ECMO treatment for ARDS continues. The aim of the study is to identify variables that affected the outcome of patients treated with VV-ECMO for severe ARDS outside a major ECMO center.

METHODS

The study included adult patients with severe ARDS treated with ECMO at a tertiary care hospital in Zagreb, Croatia between October 2009 and July 2014. Patients were recruited from a prospective database.

RESULTS

The study enrolled 40 patients, 20 of whom had H1N1-induced ARDS. The hospital mortality was 38%. The difference in mortality and long-term outcome in H1N1-induced ARDS as compared to non-H1N1-induced ARDS was not significant. Variables associated with mortality included immunosuppression, shock at time of admission, acute renal failure, occurrence of heparin-induced thrombocytopenia antibodies, nosocomial sepsis and duration of ECMO.

CONCLUSIONS

The results of our study indicate that ECMO use in severe ARDS is feasible with low mortality and identify or assert the variables associated with adverse outcomes.

Severe ARDS caused by adenovirus: early initiation of ECMO plus continuous renal replacement therapy

The reported survival rates of patients with acute respiratory distress syndrome (ARDS) caused by human adenovirus (HAdV) pneumonia are poor. The results do not differ much in immunocompetent patients supported by extracorporeal membrane oxygenation (ECMO). We report two immunocompetent patients with severe ARDS complicating HAdV pneumonia who were treated successfully and survived to discharge. Compared with previous cases, our cases might have benefited from several factors. First, the time interval between mechanical ventilator support and ECMO implantation was shorter. Second, we implemented conservative fluid management as recommended by the ARDS network using continuous renal replacement therapy (CRRT). Third, we administered an antiviral agent as early as possible. A clinical trial of early ECMO with CRRT and the administration of cidofovir in patients with severe ARDS complicating HAdV pneumonia are needed to confirm our results.

First In Vivo Results of a Novel Pediatric Oxygenator with an Integrated Pulsatile Pump

Extracorporeal membrane oxygenation (ECMO) is a pivotal bridge to recovery for cardiopulmonary failure in children. Besides its life-saving quality, it is often associated with severe system-related complications, such as hemolysis, inflammation, and thromboembolism. Novel oxygenator and pump systems may reduce such ECMO-related complications. The ExMeTrA oxygenator is a newly designed pediatric oxygenator with an integrated pulsatile pump minimizing the priming volume and reducing the surface area of blood contact. The aim of our study was to investigate the feasibility and safety of this new ExMeTrA (expansion mediated transport and accumulation) oxygenator in an animal model. During 6 h of extracorporeal circulation (ECC) in pigs, parameters of the hemostatic system including coagulation, platelets and complement activation, and flow rates were investigated. A nonsignificant trend in C3 consumption, thrombin-antithrombin-III (TAT) complex formation and a slight trend in hemolysis were detected. During the ECC, the blood flow was constantly at 500 ml/min using only flexible silicone tubes inside the oxygenator as pulsatile pump. Our data clearly indicate that the hemostatic markers were only slightly influenced by the ExMeTrA oxygenator. Additionally, the oxygenator showed a constant quality of blood flow. Therefore, this novel pediatric oxygenator shows the potential to be used in pediatric and neonatal support with ECMO.

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.

Circuit oxygenator contributes to extracorporeal membrane oxygenation-induced hemolysis

Hemolysis can occur as a consequence of extracorporeal membrane oxygenation (ECMO) and is associated with increased mortality and morbidity. Shear stress generated by flow through the circuit and oxygenator is believed to cause ECMO-induced hemolysis. We hypothesize that either a smaller dimension oxygenator or an in-line hemofilter will increase ECMO-associated hemolysis. Circuits were configured with a Quadrox-D Adult oxygenator (surface area 1.8 m), Quadrox-iD Pediatric oxygenator (surface area 0.8 m), or Quadrox-D Adult oxygenator with an in-line hemofilter (N = 4) and ran for 6 hours. Samples were collected hourly from the ECMO circuit and a time-based hemolysis control. Plasma hemoglobin levels were assayed. Circuit-induced hemolysis at each time point was defined as the change in plasma hemoglobin standardized to the time-based hemolysis control. Plasma hemoglobin increased with the use of the smaller dimension pediatric oxygenator as compared with the adult oxygenator when controlling for ECMO run time (p = 0.02). Furthermore, there was a greater pressure gradient with the smaller dimension pediatric oxygenator (p < 0.05). Plasma hemoglobin did not change with the addition of the in-line hemofilter. The use of a smaller dimension pediatric oxygenator resulted in greater hemolysis and a higher pressure gradient. This may indicate that the increased shear forces augment ECMO-induced hemolysis.

Technical-Induced Hemolysis in Patients with Respiratory Failure Supported with Veno-Venous ECMO - Prevalence and Risk Factors

The aim of the study was to explore the prevalence and risk factors for technical-induced hemolysis in adults supported with veno-venous extracorporeal membrane oxygenation (vvECMO) and to analyze the effect of hemolytic episodes on outcome. This was a retrospective, single-center study that included 318 adult patients (Regensburg ECMO Registry, 2009–2014) with acute respiratory failure treated with different modern miniaturized ECMO systems. Free plasma hemoglobin (fHb) was used as indicator for hemolysis. Throughout a cumulative support duration of 4,142 days on ECMO only 1.7% of the fHb levels were above a critical value of 500 mg/l. A grave rise in fHb indicated pumphead thrombosis (n = 8), while acute oxygenator thrombosis (n = 15) did not affect fHb. Replacement of the pumphead normalized fHb within two days. Neither pump or cannula type nor duration on the first system was associated with hemolysis. Multiple trauma, need for kidney replacement therapy, increased daily red blood cell transfusion requirements, and high blood flow (3.0–4.5 L/min) through small-sized cannulas significantly resulted in augmented blood cell trauma. Survivors were characterized by lower peak levels of fHb [90 (60, 142) mg/l] in comparison to non-survivors [148 (91, 256) mg/l, p≤0.001]. In conclusion, marked hemolysis is not common in vvECMO with modern devices. Clinically obvious hemolysis often is caused by pumphead thrombosis. High flow velocity through small cannulas may also cause technical-induced hemolysis. In patients who developed lung failure due to trauma, fHb was elevated independantly of ECMO. In our cohort, the occurance of hemolysis was associated with increased mortality.

Effects of Renal Replacement Therapy in Patients Receiving Extracorporeal Membrane Oxygenation: A Meta-Analysis

The use of renal replacement therapy (RRT) in patients receiving extracorporeal membrane oxygenation (ECMO) is increasing, but the effect of RRT on ECMO is controversial. We performed a meta-analysis to determine whether RRT is related to higher mortality in patients receiving ECMO. We searched MEDLINE, EMBASE, the Cochrane Library, and KoreaMed and found 43 observational studies with 21,624 patients receiving ECMO and then compared inpatient mortality rates of patients receiving ECMO both with and without RRT. The risk ratio (RR) of mortality between patients receiving RRT and those not receiving RRT tended to decrease as the mortality of the group not receiving RRT increased. Among patients with RRT use rates of 30% and higher, the overall mortality rates for all patients receiving ECMO tended to decrease. We found that the increase in the RR for RRT tended to be greater the longer the initiation of RRT was delayed. We suggest that in patients receiving ECMO who have high RRT use rates, RRT may decrease mortality rates.

The meaning of a high plasma free haemoglobin: retrospective review of the prevalence of haemolysis and circuit thrombosis in an adult ECMO centre over 5 years

AIMS

In adults requiring extracorporeal membrane oxygenation (ECMO), we wanted to determine; i) the frequency of elevated plasma free haemoglobin (PFHb), ii) the reasons for circuit changes and iii) whether elevated PFHb was associated with higher in-hospital mortality.

MATERIALS AND METHODS

Patients requiring ECMO between January 2010 and August 2014 were identified from a prospectively collected ECMO database. Their scanned medical records and pathology results were reviewed. Relevant patient, biochemical and circuit data were collected on an Excel spreadsheet and analysed using Stata 13 (StataCorp, College Station, TX). The patients were analysed in three groups, depending on their peak PFHb during ECMO: 'Normal PFHb' (<0.1 g/L), 'Low level PFHb' (0.1 - 0.5 g/L), 'High level PFHb' (>0.5 g/L).

MAIN RESULTS

There were 184 ECMO runs (56 VV, 128 VA) - 61 'Normal PFHb', 99 'Low level PFHb', 24 'High level PFHb'. Circuit thrombosis (pump, oxygenator) or haemolysis requiring exchanges were significantly more common in VV ECMO compared to VA ECMO - 23.21% (13/56) vs. 0.78% (1/128), p<0.001. Elevated PFHb was associated with a longer duration of haemofiltration (p<0.001) and ECMO support (p<0.001). In-hospital mortality rates for the 'Normal PFHb', 'Low level PFHb' and 'High level PFHb' groups were 16.39% (10/61), 30.30% (30/99) and 37.50% (9/24), respectively, p=0.067.

CONCLUSION

Elevated PFHb values during adult ECMO were common. Severe haemolysis or thrombosis requiring circuit changes were uncommon and occurred almost exclusively on VV ECMO. There was a non-statistically significant increase in in-hospital mortality with elevated PFHb and studies of larger registry data may clarify the prognostic value of PFHb in adult patients.

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.

Plasma Free Hemoglobin Is an Independent Predictor of Mortality among Patients on Extracorporeal Membrane Oxygenation Support

Background

Hemolysis is common in all extracorporeal circuits as evident by the elevated plasma free hemoglobin (PFHb) level. We investigated whether increased hemolysis during extracorporeal membrane oxygenation (ECMO) is an independent mortality predictor.

Methods

We performed a retrospective observational study of consecutive subjects who received ECMO at a tertiary care facility from 2007-2013 to investigate independent predictors of in-hospital mortality. We examined variables related to patient demographics, comorbidities, markers of hemolysis, ECMO characteristics, transfusion requirements, and complications. 24-hour PFHb> 50 mg/dL was used as a marker of severe hemolysis.

Results

154 patients received ECMO for cardiac (n= 115) or pulmonary (n=39) indications. Patients’ mean age was 51 years and 75.3% were males. Compared to nonsurvivors, survivors had lower pre-ECMO lactic acid (p=0.026), lower 24-hour lactic acid (p=0.023), shorter ECMO duration (P=0.01), fewer RBC transfusions on ECMO (p=0.008) and lower level of PFHb 24-hours post ECMO implantation (p=0.029). 24-hour PFHb> 50 mg/dL occurred in 3.9 % versus 15.5% of survivors and nonsurvivors, respectively, p=0.002. A Cox proportional hazard analysis identified PFHb> 50 mg/dL 24-hours post ECMO as an independent predictor of mortality (OR= 3.4, 95% confidence interval: 1.3 – 8.8, p= 0.011).

Conclusion

PFHb> 50 mg/dL checked 24-hour post ECMO implantation is a useful tool to predict mortality. We propose the routine checking of PFHb 24-hours after ECMO initiation for early identification and treatment of the cause of hemolysis.