Efficacy of venovenous extracorporeal membrane oxygenation for neonates with respiratory and circulatory compromise

Complications and mortality of venovenous extracorporeal membrane oxygenation in the treatment of neonatal respiratory failure: a systematic review and meta-analysis

Background

Extracorporeal membrane oxygenation (ECMO) has been increasingly used for severe neonatal respiratory failure refractory to conventional treatments. To systematically evaluate the complications and mortality of venovenous ECMO (VV ECMO) in the treatment of neonatal respiratory failure, we performed a systematic review and meta-analysis of all the related studies.

Methods

PubMed, Embase, and Cochrane Library were searched. The retrieval period was from the establishment of the database to February 2019. Two investigators independently screened articles according to the inclusion and exclusion criteria. The quality of article was assessed by the Newcastle-Ottawa scale (NOS). The meta-analysis was performed by Stata 15.0 software.

Results

Four observational studies were included, with a total of 347 newborns. VV ECMO was used for neonates with refractory respiratory failure unresponsive to maximal medical therapy. Median ages of the newborns at cannulation were 43.2 h, 23 h, 19 h, and 71 h in the included four studies, respectively. The overall mortality at hospital charge was 12% (5–18%) with a heterogeneity of I² = 73.8% (p = 0.01). Two studies reported mortality during ECMO and after decannulation, with 10% (0.8–19.2%) and 6.1% (2.6–9.6%), respectively. The most common complications associated with VV ECMO were: pneumothorax (20.6%), hypertension (20.4%), cannula dysfunction (20.2%), seizure (14.9%), renal failure requiring hemofiltration (14.7%), infectious complications (10.3%), thrombi (7.4%), intracranial hemorrhage or infarction (6.6%), hemolysis (5.3%), cannula site bleeding (4.4%), gastrointestinal bleeding (3.7%), oxygenator failure (2.8%), other bleeding events (2.8%), brain death (1.9%), and myocardial stun (0.9%).

Conclusion

The overall mortality at discharge of VV ECMO in the treatment of neonatal respiratory failure was 12%. Although complications are frequent, the survival rate during hospitalization is still high. Further larger samples, and higher quality of randomized controlled trials (RCTs) are needed to clarify the efficacy and safety of this technique in the treatment of neonatal respiratory failure.

Extracorporeal Membrane Oxygenation with Veno-Venous Bypass and Apneic Oxygenation for Treatment of Severe Neonatal Respiratory Failure

Seven newborn infants with life-threatening respiratory failure were treated with veno-venous (V-V) extracorporeal lung support and apneic oxygenation after maximal ventilatory and pharmacological treatment failed. Diagnosis were meconium aspiration syndrome in 3 cases, respiratory distress syndrome in 2, sepsis in 1, congenital diaphragmatic hernia in 1. Before ECMO 6 infants received tolazoline, 4 surfactant, 3 high frequency ventilation, 1 prostaglandin E, 1 epoprostenol, 2 nitric oxide. Newborns were highly hypoxemic at admission and all but one underwent rescue cannulation. V-V bypass was performed with a single lumen single cannula and tidal flow was generated by an alternating clamp using a non-occlusive roller pump. The mean duration of bypass was 162, 4±162.3 hours and infants were extubated 94.5±74.8 hours after decannulation. Five newborns survived and two died. Growth and neurologic development of the older children is normal. The extracorporeal lung support with V-V bypass associated with apneic oxygenation was effective in reversing severe neonatal respiratory failure unresponsive to maximal ventilatory and pharmacological support. An early referral, prior to meeting ECMO criteria, is important in order to avoid hypoxic complications preceding ECMO.

Prognosis and Outcome of Neonates Treated Either with Veno-Arterial (VA) or Veno-Venous (VV) ECMO

A comparison was done between neonates requiring veno-arterial (VA) ECMO (too small jugular vein, inability to insert a 12 Fr double lumen catheter or cardio-circulatory instability) and neonates treated with veno-venous (VV) ECMO in the same period of time. From 1991-1995 ECMO was done in 48 neonates after failure of maximum conventional treatments, NO-inhalation and HFOV. 30/48 babies were treated with VV-ECMO, with a switch to VA-ECMO later on in 3 of them. In 18 infants VA-ECMO was installed primarily. Differences between the VA- and VV-ECMO group were: the 01 was higher in the VV-treated babies (62±20 vs. 48±13, p < 0.03), as were birth weight (3385±570 vs. 2963±653 g, p< 0.04), gestational age (39.7 ± 1.6 vs. 37.9 ± 2.7 weeks, p< 0.01) and MAP (18.7 ± 2.2 vs. 17.1 ± 2.4 cm H2O, p< 0.05). Severe ICH's occurred more frequently in the VA-treated babies (29 vs. 7%, p< 0.05), the rate of other complications was equal. The mortality rates were 43% (VA) and 15% (VV), p< 0.05. About one third of neonatal ECMO candidates will be treated with VA-ECMO, even if the VV-ECMO technique is available. Need for VA-ECMO implies - due to a higher number of preterm babies and a greater severity of illness before ECMO - a higher incidence of ICH's and a higher mortality rate.

Venoarterial Extracorporeal Life Support for Neonatal Respiratory Failure: Indications and Impact on Mortality

Venoarterial (VA) extracorporeal life support (ECLS) for neonatal respiratory failure is associated with increased mortality compared with venovenous (VV) ECLS. It is unclear whether this is a causal relationship or reflects differences in baseline disease severity between infants managed with these two strategies. Our objective was to identify clinical variables associated with the preferential selection of VA over VV ECLS, as these may confound the association between VA ECLS and increased mortality. We identified documented indications for preferential VA selection through chart review. We then assessed how the presence of common indications impacted mortality. Thirty-nine cases met eligibility. Severity of hypotension/degree of inotropic support and ventricular dysfunction on echocardiogram before cannulation were the most common specific indications for preferential VA ECLS. Mortality was 12.5% when neither high inotropic support nor ventricular dysfunction was present. Mortality rose to 20% with high inotropic support and 25% with ventricular dysfunction present alone and to 50% when both were present. We conclude that severe hypotension and ventricular dysfunction before ECLS cannulation are common indications for VA ECLS that likely influence survival. Research assessing the impact of ECLS cannulation mode on survival should adjust for baseline differences between groups for these important variables.

Extracorporeal Life Support in Pediatric and Neonatal Critical Care: A Review

Extracorporeal life support (ECLS) is a modified form of cardiopulmonary bypass used to provide prolonged tissue oxygen delivery in patients with respiratory and/or cardiac failure. The first large-scale success of ECLS was achieved in the management of term newborns with respiratory failure. ECLS has become an accepted therapeutic modality for neonates, children, and adults who have failed conventional therapy and in whom cardiac and/or respiratory insufficiency is potentially reversible. The use of ECLS allows one to reduce other cardiopulmonary supports and apply a gentle ventilation strategy in a population of severely compromised critical care patients. ECLS has now been employed in more than 26,000 neonatal and pediatric patients with an overall survival rate of 68%. ECLS has evolved significantly over 25 years of clinical practice; patient selection for this complex and highly invasive therapy, as well as how ECLS is employed in different patient groups, is constantly changing. Generally, ECLS is used more liberally now than in the past. The number of patients requiring this support, however, is declining yearly, and those patients who receive ECLS compose a more severe subset of an intensive care population. This review provides an overview of the development of ECLS and the equipment and techniques employed. The use of ECLS for neonatal respiratory failure, pediatric respiratory failure, and cardiac support are outlined. Management of the ECLS patient is discussed in detail, and outcome of these patients is reviewed. Finally, current trends and future implications of ECLS in neonatal and pediatric critical care are addressed.

The potential of accurate SVO2 monitoring during venovenous extracorporeal membrane oxygenation: an in vitro model using ultrasound dilution

Introduction. Some degree of recirculation occurs during venovenous extracorporeal membrane oxygenation (VV ECMO) which, (1) reduces oxygen (O2) delivery, and (2) renders venous line oxygen saturation monitoring unreliable as an index of perfusion adequacy. Ultrasound dilution allows clinicians to rapidly monitor and quantify the percent of recirculation that is occurring during VV ECMO. The purpose of this paper is to test whether accurate patient mixed venous oxygen saturation (SVO2) can be calculated once recirculation is determined. It is hypothesized that it is possible to derive patient mixed venous saturations by integrating recirculation data with the ECMO circuit arterial and venous line oxygen saturation data. Methods. A test system containing sheep blood adjusted to three venous saturations (low-30%, med-60%, high-80%) was interfaced via a mixing chamber with a standard VV ECMO circuit. Recirculation, arterial line and venous line oxygen saturations were measured and entered into a derived equation to calculate the mixed venous saturation. The resulting value was compared to the actual mixed venous saturation. Results. Recirculation was held constant at 30.5 ± 2.0% for all tests. A linear regression comparison of “actual” versus “calculated” mixed venous saturations produced a correlation coefficient of R2 = 0.88. Direct comparison of actual versus calculated saturations for all three test groups respectively are as follows; Low: 31.8 ± 3.95% vs. 37.0 ± 6.7% (NS), Med: 61.7 ± 1.5% vs. 72.3 ± 1.8% (p < 0.05), High: 84.4 ± 0.9% vs. 91.2 ± 1.1% (p < 0.05). Discussion. There was a strong correlation between actual and calculated mixed venous saturations; however, significant differences between actual and calculated values where observed at the Med and High groups. While this data suggests that using quantified recirculation data to calculate SVO2 is promising, it appears that a straightforward derivative of the oxygen saturation-based equation may not be sufficient to produce clinically accurate calculations of actual mixed venous saturations. Perfusion (2007) 22, 239—244.

Successful primary use of VVDL+V ECMO with cephalic drain in neonatal respiratory failure

OBJECTIVE

To describe the use of double-lumen venovenous (VVDL) extracorporeal membrane oxygenation (ECMO) with cephalic draining cannula (VVDL+V) as a primary approach for all neonatal respiratory diagnoses and to compare our single-center experience with data as collected in the Extracorporeal Life Support Organization (ELSO) database.

STUDY DESIGN

We retrospectively reviewed all cases of ECMO for neonatal respiratory failure performed in the neonatal intensive-care unit at a large referral children's hospital, the Children's Healthcare of Atlanta at Egleston (CHOA-E). Comparisons were then made to neonatal respiratory ECMO data retrieved from the ELSO database.

RESULTS

At CHOA-E 162 of 189 cases were completed with the VVDL+V approach. Survival in the VVDL+V cohort was 89.1% versus 68.7% from ELSO, P<0.001. For those complications considered, the overall risk of complication favored the CHOA-E VVDL+V group as compared with ELSO (odds ratio (OR) 0.71 (0.52-0.7)) as did the risk of neurologic complications (OR 0.29, (0.15-0.58)), including intracranial hemorrhage (OR 0.39 (0.18-0.97), P=0.011).

CONCLUSION

The VVDL+V approach can be used successfully as the primary approach for ECMO for neonatal respiratory failure of various etiologies and in this single-center cohort this approach was associated with improved survival and lower rates of complication as compared with the ELSO database.

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

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

Outcomes comparing dual-lumen to multisite venovenous ECMO in the pediatric population: the Extracorporeal Life Support Registry experience

PURPOSE

The purpose of this study is to evaluate outcomes associated with single site dual-lumen venovenous cannulas (VVDL) and to compare them to those associated with multisite VV ECMO (VVMS) cannulation.

METHODS

The Extracorporeal Life Support (ELSO) Registry was reviewed to identify all children 31days to 18years treated with venovenous ECMO from 1998 to 2011 using either VVDL or VVMS techniques. Patient demographics, cannula type, ECMO variables, complications, and patient survival were analyzed.

RESULTS

From 1998 to 2011, 1323 children underwent venovenous ECMO. The annual utilization of VVDL cannulas has increased and recently surpassed VVMS. Fifty-four percent (n=717) of patients had VVDL cannulation. This group was significantly younger and weighed less than the VVMS group. VVDL cannulas demonstrated improved weight-adjusted flow performance than traditional cannulation. Overall survival was comparable, 64.4% and 68.6%, for VVMS and VVDL respectively. VVDL cannulas experienced higher mechanical (26.2% vs. 22.5%; p=0.004) and cardiovascular complications rates (24.4% vs. 21.7%; p=0.03) than VVMS cannulas, but when stratified by VVDL cannula type, there were no differences between wire-reinforced and non-wire reinforced cannulas.

CONCLUSIONS

VVDL cannulation has become the preferred modality for ECMO therapy in children with respiratory failure and it is mainly utilized in younger patients. The use of newer VVDL cannulas may provide improved pump flow performance without substantial additional risk.

[Particularities of ECMO in acute respiratory distress syndrome in pediatrics]

Les techniques de circulation extracorporelle sont utilisées en pédiatrie dans les syndromes de détresse respiratoire aiguë (SDRA) les plus graves depuis les années 1980. Les données du registre international de l’Extracorporeal Life Support Organization révèlent plus 5 000 enfants placés en extracorporeal membrane oxygenation (ECMO) en 2012 avec une augmentation du nombre de cas annuels depuis l’épidémie de 2009. La survie, de 56 %, est stable alors que le nombre d’enfants avec des comorbidités augmente grâce aux améliorations apportées au matériel. Bien que nous ne disposions pas d’études randomisées, ces résultats encouragent à proposer l’ECMO dans l’arsenal thérapeutique du SDRA de l’enfant. Si les techniques veinoveineuses doivent être privilégiées dans les affections respiratoires, l’ECMO veinoartérielle peut être nécessaire et reste d’une utilisation fréquente chez l’enfant (50 % des cas). En pédiatrie, les particularités techniques sont liées d’une part aux particularités physiologiques de l’enfant et d’autre part aux contraintes dues au matériel proposé selon les différentes catégories d’âge. L’ECMO est une technique de recours lourde qui nécessite une expertise à la fois technique et pédiatrique spécialisée en raison de ce terrain particulier.

Successful liver transplantation following veno-arterial extracorporeal membrane oxygenation in a child with fulminant Wilson disease and severe pulmonary hemorrhage: a case report

Massive pulmonary hemorrhage and other serious cardiopulmonary diseases in patients with fulminant hepatitis result not only in graft failure but also mortality after LT. ECMO is used to treat children with cardiorespiratory failure refractory to conventional intensive care. We describe a five-yr-old girl with genetically confirmed fulminant Wilson disease and severe pulmonary hemorrhage who underwent successful primary LT following veno-arterial ECMO. To our knowledge, this is the first report of successful primary LT in a patient using veno-arterial ECMO. The present case demonstrates that ECMO, as a bridging modality to LT, may be necessary to manage both massive pulmonary hemorrhage and possible graft loss because of hypoxemia.

Evaluation of the new generation dual-lumen catheter for neonatal ECMO

Objectives:

The purpose of this study was to compare the newly designed dual-lumen venovenous catheter (VR13, OriGen Biomedical, Austin, TX) with the current dual-lumen catheter (VV12, OriGen Biomedical).

Methods:

Five newborn lambs, 1 to 5 days old and weighing 4.2 ± 0.5 kg, were cannulated with the VV13 OriGen catheter and placed on extracorporeal membrane oxygenation (ECMO). ECMO flows were increased from 200 to 600 ml/min, with measurements taken after the changes. The experiment was then repeated using the VV12 catheter.

Results:

Recirculation values were equal for both catheters. The pressure drop at the reinfusion port was equal for both catheters at 200 ml/min, increasing to 275 mmHg at 500 ml/min for the VR13 vs. 240 mmHg for the VV12 catheter.

Conclusion:

These findings indicate that the VR13 catheter resulted in levels of recirculation equal to the VV12. Based on resistance measurements, we do not recommend the use of this new catheter beyond 400 ml/min until minor design changes are made.

The impact of ethnic population dynamics on neonatal ECMO outcomes: a single urban institutional study

INTRODUCTION

Neonatal extracorporeal membrane oxygenation ECMO has been clinically used for the last 25 y. It has been an effective tool for both cardiac and non cardiac conditions. The impact of ethno-demographic changes on ECMO outcomes however remains unknown. We evaluated a single institution's experience with non cardiac neonatal ECMO over a 28-y period.

METHODS

A retrospective review of all neonates undergoing noncardiac ECMO between the y 1984 and 2011 was conducted and stratified into year groups I, II, III (≤1990, 1991-2000, and ≥2001). Demographic, clinical, and outcome data were collected. The patient specifics, ECMO type, ECMO length, blood use, complications, and outcomes were analyzed. Univariate, bivariate, and multivariate analyses were then performed.

RESULTS

Data was available for 827 patients. The number of African-American and Hispanic patients increased over the last 27 y (27.5% versus 45.0% and 3.3% versus 21.5%, year group I versus year group III, respectively). The proportion of congenital diaphragmatic hernia (CDH) patients by ethnicity also increased for African-Americans and Hispanics between the two year groups (22.0% to 33.0% and 4.9% to 33.0%, respectively). Similar pattern was noted for non-CDH diagnoses. Low birth weight, low APGAR scores, CDH, primary pulmonary hypertension, central nervous system hemorrhage, and ECMO were independent predictors of mortality. Ethnicity, in itself however, was not associated with mortality on adjusted analysis.

CONCLUSION

More African-Americans and Hispanics have required ECMO over the years with a concurrent decrease in the number of Caucasians. While ethnicity was not an independent predictor of mortality, it appears to be a surrogate for fatal but sometime preventable diagnoses among minorities. Further investigations are needed to better delineate the reason behind this disparity.

Use of venovenous extracorporeal life support in pediatric patients for cardiac indications: a review of the Extracorporeal Life Support Organization registry

OBJECTIVE

To describe survival outcomes for pediatric patients supported on venovenous extracorporeal life support with cardiac indications and identify predictors of successful application of venovenous extracorporeal life support.

DESIGN

Retrospective review of Extracorporeal Life Support Organization registry database.

SETTING

Data reported from extracorporeal membrane oxygenation centers to the Extracorporeal Life Support Organization.

PATIENTS

Patients ≤18 yrs of age with cardiac diagnoses initiated on venovenous extracorporeal life support during 1985 to 2007.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 8,551 reported pediatric extracorporeal life support cases for cardiac indications during 1985 to 2007, 133 patients received venovenous extracorporeal life support (1.6%); 56 (42%) survived to hospital discharge, comprising the venovenous success group. Of 77 (58%) in the venovenous failure group, 45 (34%) died on venovenous extracorporeal life support and 32 (24%) were converted to venoarterial extracorporeal life support. Median duration of extracorporeal life support course was shorter in the venovenous success group (76 vs. 133 hrs, odds ratio 1.01, 95% confidence interval 1.00-1.01). In the univariate analysis, patients in the venovenous failure group had lower median arterial pH (odds ratio 0.06, 95% confidence intervals 0.01-0.61) and higher PaO(2) (odds ratio 1.02, 95% confidence interval 1.00-1.04). Complications from extracorporeal life support, including receipt of renal replacement therapy (odds ratio 4.35, 95% confidence interval 1.87-10.11), surgical hemorrhage (odds ratio 2.56, 95% confidence interval 1.05-6.25), use of inotropic infusions (odds ratio 2.53, 95% confidence interval 1.24-5.15), and infections (odds ratio 4.99, 95% confidence interval 1.07-23.25), were associated with increased odds for venovenous failure. In a multivariable model, the highest PaO(2) (PaO(2) ≥52 torr) compared to the lowest (PaO(2) ≤ 22 torr) (odds ratio 3.75, 95% confidence interval 1.11-12.57), and use of renal replacement therapy (odds ratio 4.35, 95% confidence interval 1.8710.11) were associated with increased odds of venovenous failure.

CONCLUSION

Venovenous extracorporeal life support appears to be an appropriate choice in some children with cardiac failure but better definition of this population is needed.

Extracorporeal CO(2) removal in ARDS

Acute respiratory distress syndrome remains one of the most clinically vexing problems in critical care. As technology continues to evolve, it is likely that extracorporeal CO(2) removal devices will become smaller, more efficient, and safer. As the risk of extracorporeal support decreases, devices' role in acute respiratory distress syndrome patients remains to be defined. This article discusses the functional properties and management techniques of CO(2) removal and intracorporeal membrane oxygenation and provides a glimpse into the future of long-term gas-exchange devices.

Calculating mixed venous saturation during veno-venous extracorporeal membrane oxygenation

INTRODUCTION

Recirculation (R), the shunting of arterial blood back into to the venous lumen, commonly occurs during veno-venous extracorporeal membrane oxygenation (VV-ECMO) and renders the monitoring of the venous line oxygen saturation no longer reflective of patient mixed venous oxygen saturation (S(V)O(2)). Previously, we failed to prove the hypothesis that, once R is known, it is possible to calculate the S(V)O(2) of a patient on VV-ECMO. We hypothesize that we can calculate S(V)O(2) during VV-ECMO if we account for and add an additional correction factor to our model for dissolved oxygen content. Therefore, the purpose of this study is to derive a more accurate model that will allow clinicians to determine S(V)O(2) during VV-ECMO when ultrasound dilution is being used to quantify R.

METHODS

Using an extracorporeal circuit primed with fresh porcine blood, two stocks of blood were produced; (1) arterial blood (AB), and (2) venous blood (VB). To mimic recirculation, the AB and VB were mixed together in precise ratios using syringes and a stopcock manifold. Six paired stock AB/VB sets were prepared. Two sets were mixed at 20% R increments and 4 sets were mixed at 10% R increments. The partial pressure of oxygen (pO(2) ) and oxygen (O(2)) saturation of the stock blood and resultant mixed blood was determined. The original model was modified by modeling the residual errors with linear regression.

RESULTS

When using the original model, as the partial pressure of arterial oxygen (P(a)O( 2)) of the stock AB increased, the calculated S(V)O(2) was higher than actual, especially at higher R levels. An iteration of the original model incorporating the P(a)O(2) level (low, medium, high) and R was derived to fit the data.

CONCLUSIONS

The original model using R and circuit saturations for the calculation of S(V)O( 2) in VV-ECMO patients is an oversimplification that fails to consider the influence of the high pO(2) of arterial blood during therapy. In the future, further improvements in this model will allow clinicians accurately to calculate S(V)O(2) in conjunction with recirculation measurements.

Hypoxic respiratory failure in the late preterm infant

Hypoxic respiratory failure in late preterm infants has received increased attention in the last decade, and while the incidence is low, it accounts for a significant number of admissions to neonatal ICUs because of the large number of late preterm births in the United States and worldwide. Causes of respiratory distress include transient tachypnea of the newborn, surfactant deficiency, pneumonia, and pulmonary hypertension. The physiologic mechanisms underlying delayed transition caused by surfactant deficiency and poor fetal lung fluid absorption have been reviewed recently elsewhere. This article focuses on the less-explored problem of severe hypoxic respiratory failure in the late preterm infant and discusses potential strategies for management.

Extracorporeal life support

Extracorporeal life support (ECLS) denotes the use of prolonged extracorporeal cardiopulmonary bypass in patients with acute, reversible cardiac or respiratory failure. As technology has advanced, organ support functions other than gas exchange, such as liver, renal, and cardiac support, have been provided by ECLS, and others, such as immunologic support, will be developed. The future of ECLS will include improvements in devices accompanied by circuit simplification and auto-regulation. Such enhancements in technology will allow application of ECLS to populations currently excluded from such support; for example, thromboresistant circuits will eliminate the need for systemic anticoagulation and lead to the use of this technique in premature newborns. As the ECLS technique becomes safer and simpler, and as morbidity and mortality are minimized, criteria for application of ECLS will be relaxed. New approaches to ECLS, such as pumpless arteriovenous bypass, the artificial placenta, arteriovenous CO(2) removal (AVCO(2)R), and intravenous oxygenators (IVOX), will become more commonly applied. Such advances in technology will allow broader and more routine application of ECLS for lung and other organ system failure.

Extracorporeal Therapies in the Treatment of Sepsis: Experience and Promise

Desire to restore the balance of body elements has enamored physicians since the ancient practice of bloodletting. More recently, extracorporeal techniques have been employed in both adults and children in treating sepsis. Extracorporeal therapies include continuous renal replacement (CRRT), plasma-based removal techniques, and extracorporeal membrane oxygenation (ECMO). These treatments could theoretically 1) provide immunohomeostasis of pro- and anti-inflammatory cytokines and other sepsis mediators, 2) decrease organ microthrombosis through removal of pro-coagulant factors and modulating the impaired septic coagulation response in sepsis, and 3) provide mechanical support of organ perfusion during the acute septic episode to allow time for response to traditional sepsis therapies and antimicrobials. CRRT is beneficial in managing fluid overload and acute renal failure in sepsis. Removal of sepsis mediators through the technique is variable, and the outcome impact of CRRT on sepsis has not been definitively determined. High-flow CRRT has demonstrated benefit in septic adults. Intriguing early results suggest that plasma exchange could improve outcomes in both adults and children. Based on experience, ECMO is recommended for refractory septic shock in neonates and should be considered for use in children. Ongoing trials may help determine whether the promise of extracorporeal therapies translates into outcome improvement in septic children.

Changes of lactate, glucose, ionized calcium and glutamate concentrations in cephalic vein blood during brain hypothermia using extracorporeal membrane oxygenation (ECMO) in a newborn infant with hypoxic-ischemic encephalopathy

An asphyxiated infant with severe hypoxic-ischemic encephalopathy was treated by brain hypothermia using extracorporeal membrane oxygenation (ECMO). The brain hypothermia using ECMO maintained cardiopulmonary functions and stabilized brain temperatures by stably supply of the cooled blood to the brain. Moreover,we measured the levels of glucose, lactate, ionized calcium and glutamate in plasma. The comparison between these levels in the artery and in the cephalic vein, suggests that glucose, lactate, ionized calcium and glutamate might be used as markers of the effects of hypothermia therapy.

Extracorporeal membrane oxygenation in infants with meconium aspiration syndrome: a decade of experience with venovenous ECMO

BACKGROUND

Despite the emergence of new therapies for respiratory failure of the newborn with meconium aspiration syndrome (MAS), extracorporeal membrane oxygenation (ECMO) has a significant role as a rescue modality in these infants. Our objective was to compare the use of venovenous (VV) vs venoarterial (VA) ECMO in newborns with MAS who need ECMO and to ascertain the impact of new therapies in these infants during the last decade. We also evaluated how disease severity or time of ECMO initiation affected mortality and morbidity.

METHODS

A report of 12 years experience (1990-2002) of a single center, comparing VV and VA ECMO, is given. Venovenous ECMO was the preferred rescue modality for respiratory failure unresponsive to maximal medical therapy. Venoarterial ECMO was used only when the placement of a VV ECMO 14-F catheter was not possible; 128 patients met ECMO criteria, 114 were treated with VV ECMO, and 12 with VA ECMO. Two patients were converted from VV to VA ECMO.

RESULTS

Venovenous and VA ECMO patients had comparable birth weight (mean +/- SEM, 3.48 +/- 0.05 vs 3.35 +/- 0.15 kg) and gestational age (40.3 +/- 0.1 vs 40.7 +/- 0.3 weeks). Before ECMO, there was no difference between VV and VA ECMO patients in oxygenation index (60 +/- 3 vs 63 +/- 8), mean airway pressure (19.5 +/- 0.4 vs 20.8 +/- 1.5 cm H2O), alveolar-arterial O2 gradient (630 +/- 2 vs 632 +/- 4 torr), ECMO cannulation age (median [25th-75th percentiles], 23 [14-47] vs 26 [14-123] hours), or in the % of patients who needed vasopressors/inotropes (98% vs 100%). From November 1994, inhaled nitric oxide (NO) was available. Before VV ECMO, 67% of the patients received NO, 24% received surfactant, and 48% were treated with high-frequency ventilation (HFV). There was no significant difference between VV and VA ECMO patients in survival rate (94% vs 92%), ECMO duration (88 [64-116] vs 94 [55-130] hours), time of extubation (9 [7-11] vs 14 [9-15] days), age at discharge (23 [18-30] vs 27 [15-41] days), or incidence of short-term intracranial complications (5.3% vs 16.7%). For the total cohort of 126 infants, indices of disease severity (oxygenation index, alveolar-arterial O 2 gradient, mean airway pressure) did not correlate with outcome measures. Delay in ECMO initiation (> 96 hours) was associated with prolonged mechanical ventilation and hospitalization (P < .01). New therapies (NO, HFV, surfactant) in the second part of the decade were associated with a longer ECMO duration (98 [80-131] vs 87 [60-116] hours; P < .05), no delay in ECMO initiation time (23 [10-40] vs 24 [14-52] hours), and no significant change in survival (97% vs 92.5%). No patient was treated with VA ECMO after 1994.

CONCLUSIONS

Venovenous ECMO is as reliable as VA ECMO in newborns with MAS in severe respiratory failure who need ECMO. Delay in ECMO initiation may result in prolonged mechanical ventilation and increased length of hospital stay. The emergence of new conventional therapies (NO, HFV, surfactant) and particularly increased experience enable sole use of VV ECMO with no significant change in survival in infants with MAS.

The role of extracorporeal membrane oxygenation in the management of infants with congenital diaphragmatic hernia

Many infants with CDH can be managed with conventional mechanical ventilation and pharmacotherapy. However, some infants will require levels of ventilator support that are not compatible with survival. In these circumstances, extracorporeal membrane oxygenation (ECMO) has been used with varying results. The indication, type, and timing of ECMO in relation to surgery continue to evolve in an attempt to improve the outcome. At the same time, there is growing body of literature showing adverse outcomes among infants with CDH treated with ECMO, raising questions about the usefulness of ECMO in CDH. This paper reviews some of the controversies associated with the use of ECMO in CDH.

Venovenous extracorporeal membrane oxygenation for respiratory failure in inotrope dependent neonates

It is often stated that venovenous extracorporeal membrane oxygenation (VV ECMO) should not be used in inotrope dependent patients. It is our practice to use VV ECMO in most patients with respiratory failure even though many of these patients are receiving significant doses of inotropes. Our objective was to review the mode of ECMO in relation to precannulation doses of inotropes administered to neonates treated with ECMO for respiratory failure. Forty-three consecutive case notes were reviewed. Data were collected for basic demographic and ECMO parameters. Inotropic doses were converted to a single score for ease of comparison, with one point equivalent to 1 microg/kg/min dopamine. Forty-three neonates were studied; 37(86%) were treated with VV ECMO and 6 (14%) were treated with VA ECMO. Significant pre-ECMO inotropic support (score > 10) was present in 30 (70%) of the 43 cases. Of these patients, 26 were treated via VV ECMO with a survival rate of 84%, while 4 were treated with VA ECMO with a survival of 75%. Inotrope scores fell to nonsignificant levels (< 10) within 24 hours, regardless of ECMO mode. Mean arterial blood pressure remained above precannulation levels in both groups. VV ECMO allows safe treatment of neonatal respiratory failure in the presence of significant inotropic support. We recommend VV ECMO for neonatal respiratory failure in all cases except where double lumen cannulation is impossible or when septic shock is refractory to inotropic support (i.e., mean blood pressure < 35 mm Hg despite inotrope score of > 100).

Venovenous versus venoarterial extracorporeal membrane oxygenation in congenital diaphragmatic hernia

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has a significant role as a final rescue modality in severe respiratory failure of the newborn with congenital diaphragmatic hernia (CDH). The objective of this study was to compare the efficiency of venovenous (VV) versus venoarterial (VA) ECMO in newborns with CDH.

METHODS

A retrospective report of 11 years experience (1990 through 2001) of a single center, comparing VV and VA ECMO is given. VV ECMO was the preferred rescue modality for respiratory failure unresponsive to maximal medical therapy. Only when the placement of a VV ECMO 14F catheter was not possible, VA ECMO was used. Forty-six patients met ECMO criteria; 26 were treated with VV ECMO and 19 with VA ECMO. One patient underwent conversion from VV to VA ECMO.

RESULTS

Before ECMO, there was no difference between VV and VA ECMO patients in mean oxygenation index (83 v 83), mean airway pressure (18.4 v 18.9 cm H(2)O), ECMO cannulation age (28 v 20 hours), or in the percentage of patients who needed dopamine and dobutamine (100% v 100%). From November 1994, nitric oxide (NO) was available; before ECMO, 11 of 14 (79%) VV ECMO patients received NO versus 9 of 10 (90%) patients in the VA group. VV ECMO patients were larger (3.34 v 2.77 kg; P <.05) and of advanced gestational age (39.0 v 36.9 wk; P <.05) compared with VA ECMO patients. There was no significant difference between VV and VA ECMO patients in survival rate (18 of 26, 69% v 13 of 19, 68%), ECMO duration (152 v 150 hours), time of extubation (32.0 v 33.5 days), age at discharge (73 v 81 days), or incidence of short-term intracranial complications (3.8% v 10.5%) or myocardial stun (3.8% v 15.8%).

CONCLUSIONS

The authors conclude that VV ECMO is as reliable as VA ECMO in newborns with CDH in severe respiratory failure who need ECMO support and who can accommodate the VV double-lumen catheter. Because of its potential advantages, VV ECMO may be the preferred ECMO method in these infants.

Primary use of the venovenous approach for extracorporeal membrane oxygenation in pediatric acute respiratory failure

OBJECTIVES

To describe a single center's experience with the primary use of venovenous cannulation for supporting pediatric acute respiratory failure patients with extracorporeal membrane oxygenation (ECMO).

DESIGN

Retrospective chart review of all patients receiving extracorporeal life support at a single institution.

SETTING

Pediatric intensive care unit at a tertiary care children's hospital.

PATIENTS

Eighty-two patients between the ages of 2 wks and 18 yrs with severe acute respiratory failure.

INTERVENTIONS

ECMO for acute respiratory failure.

MEASUREMENTS AND MAIN RESULTS

From January 1991 until April 2002, 82 pediatric patients with acute respiratory failure were cannulated for ECMO support. Median duration of ventilation before ECMO was 5 days (range, 1-17 days). Sixty-eight of these patients (82%) initially were placed on venovenous ECMO. Fourteen patients were initiated and remained on venoarterial support, including six in whom venovenous cannulae could not be placed. One patient was converted from venovenous to venoarterial support due to inadequate oxygenation. Venoarterial patients had significantly greater alveolar-arterial oxygen gradients and lower PaO(2)/FIO(2) ratios than venovenous patients (p <.03). Fifty-five of 81 venovenous patients received additional drainage cannulae (46 of 55 with an internal jugular cephalad catheter). Thirty-five percent of venovenous patients and 36% of venoarterial patients required at least one vasopressor infusion at time of cannulation (p = nonsignificant); vasopressor dependence decreased over the course of ECMO in both groups. Median duration on venovenous ECMO for acute hypoxemic respiratory failure was 218 hrs (range, 24-921). Venovenous ECMO survivors remained cannulated for significantly shorter time than nonsurvivors did (median, 212 vs. 350 hrs; p =.04). Sixty-three of 82 ECMO (77%) patients survived to discharge-56 of 68 venovenous ECMO (81%) and nine of 14 venoarterial ECMO (64%).

CONCLUSIONS

Venovenous ECMO can effectively provide adequate oxygenation for pediatric patients with severe acute respiratory failure receiving ECMO support. Additional cannulae placed at the initiation of venovenous ECMO could be beneficial in achieving flow rates necessary for adequate oxygenation and lung rest.

Improved oxygenation with reduced recirculation during venovenous ECMO: comparison of two catheters

OBJECTIVES

To determine whether the new double-lumen catheter made by OriGen Biomedical (Austin, TX) for venovenous (VV) extracorporeal membrane oxygenation (ECMO) would reduce recirculation and improve oxygenation during VV ECMO when compared with the Kendall double-lumen catheter (Kendall Healthcare Products, Mansfield, MA).

DESIGN

Prospective intervention study.

SETTING

The animal research laboratory at Children's National Medical Center, Washington, DC.

SUBJECTS

Nine newborn lambs one to seven days old and weighing 4.4 +/- 0.8 kg.

INTERVENTION

Animals were anesthetized, intubated, and ventilated. The ductus arteriosus was ligated. Femoral arterial and venous, cephalic jugular vein, and pulmonary artery catheters were placed. After systemic heparinization, the catheter to be tested, an OriGen catheter, was placed in the right internal jugular vein and advanced into the right atrium. The animal was placed on ECMO and stabilized, with the ventilator settings decreased to a peak inspiratory pressure of 15-20 cmH2O, peak end-expiratory pressure of 5 cmH2O, rate of 15-25 breaths/min, and a fractional inspired oxygen concentration of 0.21-0.30. ECMO flows were increased in 100-ml increments from 200 to 600 ml/min with measurements taken 15 min after each change. The OriGen catheter was removed, the Kendall catheter was placed, and the studies were repeated.

MEASUREMENTS AND MAIN RESULTS

Heart rate, mean blood pressure, PaO2, jugular cerebral oxygen saturation, pulmonary artery oxygen saturation, pump venous oxygen saturation, and postmembrane circuit pressures were measured at each study period. The OriGen catheter improved oxygenation, with higher systemic PaO2, higher pulmonary artery and cerebral oxygen saturations, and lower pump venous oxygen saturations (indicating less recirculation). With the OriGen catheter, PaO2 levels ranged from 69 +/- 18 mmHg [9.2 +/- 2.4 kPa] to 114 +/- 45 mmHg [15.2 +/- 6.0 kPa], compared range from 61 +/- 15 mmHg [8.1 +/- 2.0 kPa] to 87 +/- 34 mmHg [11.5+/-4.5 kPa] for the Kendall catheter. These findings indicate that, at all flow rates studied, less recirculation occurred with the OriGen catheter than with the Kendall catheter. The postmembrane pressures were significantly lower for the OriGen catheter at any given flow (from 30 +/- 5 to 122 +/- 18 mmHg) when compared with the Kendall catheter (from 77+/- 16 to 330+/-78 mmHg).

CONCLUSIONS

These findings indicate that the OriGen catheter resulted in a reduction of recirculation, thereby resulting in an improvement in oxygenation while on VV ECMO. The lower postmembrane pressure potentially could reduce the risk of ECMO circuit complications such as tubing rupture, bleeding complications, as well as hemolysis. This new catheter makes VV ECMO more effective and represents a design that could be used for neonatal and/or pediatric ECMO.

Support of respiratory failure in the pediatric surgical patient

Severe respiratory failure in newborn and pediatric patients is associated with significant morbidity and mortality. Basic science laboratory investigation has led to advances in the understanding of ventilator-induced lung injury and in optimizing the supportive use of conventional ventilation strategies. Over the past few years, progress has been made in alternative therapies for supporting children and adults with severe respiratory failure. This review will focus on recent laboratory and clinical data regarding the techniques of lung protective ventilator strategies, inhaled nitric oxide, liquid ventilation, and extracorporeal life support (ECLS, ECMO). Some of these modalities are commonplace, while others may have much to offer the pediatric clinician if their benefit is clearly demonstrated in future clinical trials.

Neonatal and pediatric extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation provides an external circulation for the critically ill patient with components capable of supporting the cardiorespiratory system while the patient's innate organs recover from the primary insult. This therapy is often used in children with relatively well-elucidated indications. Although initially used in the setting of neonatal respiratory failure, the use of extracorporeal membrane oxygenation for pediatric respiratory and cardiac indications is not uncommon. The complications and the outcomes of extracorporeal membrane oxygenation compare favorably with other forms of conventional therapy.

Venoarterial versus venovenous extracorporeal membrane oxygenation in congenital diaphragmatic hernia: the Extracorporeal Life Support Organization Registry, 1990-1999

BACKGROUND/PURPOSE

Venoarterial (VA) extracorporeal membrane oxygenation (ECMO) traditionally has been the mode of support used in congenital diaphragmatic hernia (CDH). A few studies report success using venovenous (VV) ECMO. The purpose of this study is to compare outcomes in CDH patients treated with VA and VV.

METHODS

The authors queried the Extracorporeal Life Support Organization Registry for newborns with CDH treated with ECMO from January 1, 1990 through December 31, 1999. They analyzed the pre-ECMO data, ECMO course, and complications.

RESULTS

VA was utilized in 2,257 (86%) and VV in 371 (14%) patients. The pre-ECMO status was similar, with greater use of nitric oxide, surfactant, and pressors in VV. Survival rate was similar (58.4% for VV and 52.2% for VA, P =.057). VA was associated with more seizures (12.3% v 6.7%, P =.0024) and cerebral infarction (10.5% v 6.7%, P =.03). Sixty-four treatments were converted from VV to VA (VV-->VA). Survival rate in VV-->VA was not significantly different than VA (43.8% v 52.2%, respectively; P =.23). VV-->VA and VA patients had similar neurologic complications.

CONCLUSIONS

CDH patients treated with VV and VA have similar survival rates. VA had more neurologic complications. The authors identified no disadvantage to the use of VV as an initial mode of ECMO for CDH, although some infants may need conversion to VA.

The changing demographics of neonatal extracorporeal membrane oxygenation patients reported to the Extracorporeal Life Support Organization (ELSO) Registry

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is an important treatment tool in the management of near-term and term neonates with severe hypoxemic respiratory failure. To better understand how health care for patients treated with ECMO has changed, we studied the demographic and treatment data reported to the Extracorporeal Life Support Organization (ELSO) registry from January 1, 1988, through January 1, 1998.

METHODS

We used data stored in the ELSO registry and evaluated the changes in demographics, use of alternate therapies before ECMO, severity of illness, duration of ECMO therapy, and mortality over a 10-year period. All data on neonates reported between January 1, 1988, and January 1, 1998 were used. Verification checks were performed on all fields to eliminate nonsense outliers. We separated the neonates into 2 groups-those with and those without a congenital diaphragmatic hernia (CDH). All analyses were performed on the total group and each subgroup separately. Changes in continuous data were analyzed by year using analysis of variance. Year differences in categorical data were evaluated with chi(2) analysis. We also used the linear trend test and the Cochran-Armitage trend test to evaluate time-related changes.

RESULTS

We reviewed 12 175 neonates. Over the decade, there were no changes in mean gestational age, gender, age at which ECMO was started, pH, or PaCO(2) just before ECMO. The proportion of neonates with CDH increased from 18% to 26%, while the proportion with respiratory distress syndrome decreased from 15% to 4%. Other diagnostic categories remained constant. The use of surfactant, high-frequency ventilation, and inhaled nitric oxide increased from 0% in 1988 to 36%, 46%, and 24%, respectively, in 1997. The mean peak pressure being used just before ECMO decreased (47 +/- 10 in 1988 to 39 +/- 12 in 1997), and the mean PaO(2)/FIO(2) ratio increased (38 +/- 23 in 1988 to 48 +/- 36 in 1997). The primary mode of ECMO remains venoarterial; however, the use of venovenous ECMO increased from 1% to 32% over the decade. Duration of ECMO treatment increased overall, and this trend was seen for patients with and without CDH (124 +/- 67 to 141 +/- 104 hours for the non-CDH group, 161 +/- 99 to 238 +/- 141 hours for the CDH group). The number of centers reporting neonatal data to the ELSO registry increased from 52 in 1988 to a peak of 100 in 1993. In 1997, 96 centers reported data to ELSO. The average number of neonatal patients reported from each site decreased from a peak of 18 in 1991 to 9 in 1997. Mortality increased from 18% to 22%; however, when corrected for the relative increase in neonates with CDH, this trend disappeared. Diagnoses-specific mortality rates remained constant. The occurrence of intracranial hemorrhage and/or infarct also stayed constant at 16%.

CONCLUSIONS

The population of neonates treated with ECMO in 1997 was very different from patients treated in the 1980s and early 1990s. They were exposed to an ever-expanding group of new therapies, appeared to be healthier based on indices of gas exchange, and were cared for at centers that reported fewer cases per year.

Quantification of recirculation by thermodilution during venovenous extracorporeal membrane oxygenation

PURPOSE

The aim of this study was to determine whether recirculation could be quantified by a thermodilution technique during venovenous (VV) extracorporeal membrane oxygenation (ECMO) in a rabbit model.

METHODS

Five New Zealand white rabbits, mean weight, 4.5 (range, 3.7 to 5.7) kg, were anesthetized, instrumented, cannulated with a double-lumen catheter, and placed on VV ECMO. Serial injections of ice-cold saline were performed at the arterial arm of the circuit, and the resultant temperature change at various pump flows was measured at the venous arm of the circuit using a thermistor-tipped catheter and a cardiac output computer. Results were compared with the respective 100% recirculation measured with all the circuit flow passing through the bridge.

RESULTS

Using linear regression, recirculation percentage could be calculated as: 19 + 0.1 x pump flow (R2 = 0.81, P < .005). Recirculation correlated positively with pump flow. Variability between results at each flow was less than 10%.

CONCLUSIONS

Recirculation can be quantified during VV ECMO by measuring the change in temperature in the venous arm using a cardiac output computer after injection of a known quantity of ice-cold saline in the arterial side of the circuit. The effect of interventions to reduce recirculation can be assessed conveniently and reliably.

Two years' follow-up of newborn infants after extracorporeal membrane oxygenation (ECMO)

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is a technique of extracorporeal oxygenation used in newborn infants with refractory hypoxemia after failure of maximal conventional medical management, when mortality risk is higher than 80%. We retrospectively reviewed all the neonates treated by ECMO between October 1991 and September 1997 in our newborn intensive care unit.

METHODS

Fifty-seven patients were treated with ECMO for severe respiratory failure: congenital diaphragmatic hernia (CDH) (n=23), neonatal sepsis (NS) (n=14), meconium aspiration syndrome (MAS) (n=12), and others (n=8). Mean gestational age and birth weight were 38+/-2 weeks and 3200+/-500 g, respectively. Oxygenation index was 61+/-8. Both venovenous (n=28) or venoarterial ECMO (n=29) were used. The mean time at ECMO initiation was 47 h (range 8 h-2 months). The mean duration was 134+/-68 h. In each case of VA ECMO, carotid reconstruction was performed. Survival at 2 years was 40/57 (70%) (CDH 12/23 (52%), NS 11/14 (79%), MAS 12/12 (100%), others 5/8). Follow-up at 2 years was available in 36 survivors.

RESULTS

Neurodevelopmental outcome was not related to the initial diagnosis: normal neurologic development (n=30), cerebral palsy (n=5), and neurologic developmental delay (n=1). Two patients remained oxygen dependant at 2 years, and four required surgical treatment for severe gastroesophageal reflux. Respiratory and digestive sequelae were more frequent in the CDH group (P<0.01). Patency and flow of the repaired carotid artery was assessed in 20 infants at 1 year of age using Doppler ultrasonography: normal (n=10), <50% stenosis (n=9), and >50% stenosis (n=1).

CONCLUSION

ECMO increased survival of newborn infants with refractory hypoxemia. However, higher a survival rate and lower morbidity were found in non-CDH infants than in congenital diaphragmatic hernia.

Pathogenesis and management of respiratory insufficiency following pulmonary resection

The underlying principle of the surgical treatment of non-small-cell lung cancer (NSCLC) is complete removal of the local/regional disease within the thorax. Pulmonary resection should be as conservative as possible without compromising the adequacy of tumor removal. A multitude of factors influence the incidence and severity of complications following pulmonary resection including the pre-operative physical and psychological status of the patient, the pathologic process requiring resection, the physiologic impact of the procedure, and the addition of pre-operative or postoperative adjuvant therapy. The insidious onset of interstitial changes on chest X-ray (CXR) 1 to 2 days after pulmonary resection forewarns of respiratory distress; however, the pathophysiology of adult respiratory distress syndrome (ARDS) with progression to respiratory failure requiring mechanical ventilation and advanced critical care often unfolds. Management of patients with severe respiratory failure remains primarily supportive. "Good critical care" is the mainstay of therapy: this includes gentle mechanical ventilation to avoid ventilator-induced barotrauma and over-extension of remaining functional alveoli, diuresis, infection identification and management, and nutritional support. New therapeutic strategies that may impact on outcomes in the adult population include pressure-limited ventilation (permissive hypercapnia), inverse ratio ventilation, high-frequency jet ventilation, high-frequency oscillatory ventilation, intratracheal pulmonary ventilation, and prone position ventilation. In addition, alternative therapies such as partial liquid ventilation, inhaled nitric oxide, and extracorporeal techniques including extracorporeal membrane oxygenation (ECMO), extracorporeal carbon dioxide removal (ECCO(2)R), intravascular oxygenation (IVOX), and arteriovenous carbon dioxide removal (AVCO(2)R), provide additional modalities. A component of some or all of these strategies is finding a role in clinical practice.

Low-dose nitric oxide therapy for persistent pulmonary hypertension of the newborn. Clinical Inhaled Nitric Oxide Research Group

BACKGROUND

Inhaled nitric oxide improves gas exchange in neonates, but the efficacy of low-dose inhaled nitric oxide in reducing the need for extracorporeal membrane oxygenation has not been established.

METHODS

We conducted a clinical trial to determine whether low-dose inhaled nitric oxide would reduce the use of extracorporeal membrane oxygenation in neonates with pulmonary hypertension who were born after 34 weeks' gestation, were 4 days old or younger, required assisted ventilation, and had hypoxemic respiratory failure as defined by an oxygenation index of 25 or higher. The neonates who received nitric oxide were treated with 20 ppm for a maximum of 24 hours, followed by 5 ppm for no more than 96 hours. The primary end point of the study was the use of extracorporeal membrane oxygenation.

RESULTS

Of 248 neonates enrolled, 126 were randomly assigned to the nitric oxide group and 122 to the control group. Extracorporeal membrane oxygenation was used in 78 neonates in the control group (64 percent) and in 48 neonates in the nitric oxide group (38 percent) (P=0.001). The 30-day mortality rate in the two groups was similar (8 percent in the control group and 7 percent in the nitric oxide group). Chronic lung disease developed less often in neonates treated with nitric oxide than in those in the control group (7 percent vs. 20 percent, P=0.02). The efficacy of nitric oxide was independent of the base-line oxygenation index and the primary pulmonary diagnosis.

CONCLUSIONS

Inhaled nitric oxide reduces the extent to which extracorporeal membrane oxygenation is needed in neonates with hypoxemic respiratory failure and pulmonary hypertension.

Surgical aspects of pediatric cardiac extracorporeal membrane oxygenation

Because children with severe myocardial dysfunction have limited therapeutic options, mechanical support of a failing heart is a matter of great interest. In the setting of cardiogenic shock or severe low cardiac output and hypoperfusion, extracorporeal membrane oxygenation (ECMO) can produce decisive improvements. The criteria for successful treatment include appropriate patient selection, improved surgical techniques and experience, higher recognition and anticipation of complications, and minimized delay in initiation of ECMO. Because the need for mechanical circulatory support may arise pre-, intra-, and postoperatively, every pediatric cardiac surgeon must be familiar with the principles and the surgical aspects of ECMO.

Respiratory failure: current status of experimental therapies

A number of advances in the treatment of infants and children with respiratory failure have been investigated in the laboratory with translation to clinical practice. Investigators have recognized that application of high ventilating pressures and failure to apply adequate levels of positive end-expiratory pressure (PEEP) can inflict injury to the already failing lung. Other interventions such as prone positioning and application of new ventilating strategies such as proportional assist ventilation (PAV), inverse ratio ventilation (IRV), high frequency ventilation, liquid ventilation, and intratracheal pulmonary ventilation (ITPV), continue to be developed and explored. Administration of inhaled nitric oxide (iNO) may improve pulmonary physiology and gas exchange in patients with respiratory insufficiency. Finally, the technique of extracorporeal life support (ECLS) is being simplified and refined. This report summarizes the status of these advances and describes the basic science and clinical research that brought them to clinical application.

A centrifugal pump driven tidal flow extracorporeal membrane oxygenation system tested with neonatal mock circulation

In 1993, Chevalier published his experiences with tidal flow venovenous extracorporeal membrane oxygenation (ECMO) featuring a single lumen cannula, non-occlusive roller pump, and alternating clamps. Using a neonatal mock circulation (NMC), which enables different hemodynamic states for neonatal ECMO research, the tested hypothesis was that it is possible to create a centrifugal pump driven tidal flow neonatal venovenous ECMO system. Additionally, the resulting hemodynamic effects in a condition of circulatory impairment were investigated. The ECMO circuit tested was assembled using a pediatric centrifugal pump head, a distensible reservoir, and a rotary clamp separating drainage from the injection phase. Using the NMC, end tidal volumes, mock circulation flow, and arterial and venous pressures were measured at different pump speeds after the drainage and injection phases. Effective venovenous ECMO flow (evvEF) was calculated. Mock circulation baseline values (ECMO clamped) were compared to values during tidal flow ECMO. At 3,000 rpm, a centrifugal pump speed of 75 ml/kg/min evvEF was reached, and it increased with higher pump speeds. At this point, the end tidal mock circulation flow (representing cardiac output) after drainage differed significantly from that during the injection phase (p < 0.01) but not from the baseline value. The end tidal arterial and venous pressures after the drainage phase were found to be significantly decreased compared to the baselines (p < 0.01). In conclusion, a centrifugal pump driven tidal flow venovenous ECMO system can be created enabling sufficient tidal volumes. Tested in the described NMC simulating posthypoxic circulatory impairment, significant hemodynamic effects could be demonstrated. Animal experiments for confirmation are necessary.

The Edmonton experience with venovenous extracorporeal membrane oxygenation

BACKGROUND/PURPOSE

Despite the proven effectiveness of venovenous extracorporeal membrane oxygenation (VV ECMO) in the treatment of neonates with severe respiratory failure, this technique is not widely used. The purpose of this study was to assess the authors' policy of preferred use of VV ECMO with a cephalad catheter and to compare the results with those of the Extracorporeal Life Support Organization (ELSO) Registry.

METHODS

Charts of neonatal ECMO candidates were reviewed retrospectively. Data were collected for gestational age, birth weight, and diagnosis. Severity of illness was assessed by oxygenation index, lactate levels, and inotropic requirements before cannulation. Patients were divided into three groups: venovenous (VV), venoarterial (VA), and VV to VA ECMO. A cephalad catheter was inserted in the distal part of the jugular vein.

RESULTS

Sixty-five neonates were supported with ECMO. Cannulation with a double lumen venovenous (VVDL) catheter was attempted in 63 neonates and successfully accomplished in 57. A survival rate of 86% was observed in neonates initially placed on VV ECMO. Five neonates initially placed on VV ECMO underwent conversion to VA ECMO.

CONCLUSIONS

This study showed that the authors' preferred policy of VV ECMO did not result in an increase in mortality rate based on a comparison with ELSO data. VV ECMO with a cephalad catheter provides adequate support for unstable neonates with respiratory failure.

Venovenous extracorporeal membrane oxygenation in newborn infants using the umbilical vein as a reinfusion route

PURPOSE

The authors report on four neonates treated with venovenous (VV) extracorporeal membrane oxygenation (ECMO) using the umbilical vein as a reinfusion route.

METHODS

From 1994 to 1997, 26 instances VV-ECMO in neonates have been carried out at our neonatal center for the treatment of severe respiratory and cardiac failure. Among them, 22 patients could be treated with VV-ECMO mainly using 15F double-lumen catheter (DLC), adding the cephalic drainage using another catheter. In the remaining four cases, however, attempts to insert the DLC into the right internal jugular vein failed because the vein was too small or technical problems. For such instances, two catheters were cannulated into the right atrium and the cephalic portion of the right internal jugular vein, respectively. These two venous catheters were connected to the drainage route of ECMO circuit with a "Y" connector. Then, the umbilical vein was cannulated with 10F or 8F catheter, which was connected to the reinfusion route of ECMO to return the oxygenated blood to the infant.

RESULTS

The median age at which ECMO was initiated was 18 hours, and the median ECMO course was 72 hours. The liver function tests were slightly and transiently worsened in two patients during VV perfusion, (in one patient serum glutamic-oxaloacetic transaminase [SGOT] elevated to 76 IU/L and serum glutamic-pyruvic transaminase [SGPT] to 49 IU/L, and in another patient SGOT elevated to 56 IU/L and SGPT remained in normal range). Preumbilical cannula pressures were measured in two patients. In a patient who used 10F umbilical cannula, the preumbilical maximum pressure was 43 mm Hg at 250 mL/min of ECMO flow. In another with an 8F catheter, it was 72 mm Hg at 180 mL/min of ECMO flow. All of the patients survived without any neurological complications.

CONCLUSIONS

If the right internal jugular vein would not accommodate the DLC, VV-ECMO using the umbilical vein as a infusion route could be selected.

Congenital diaphragmatic hernia: developing a protocolized approach

BACKGROUND/PURPOSE

The purpose of this study was to evaluate the evolving outcome of newborns who have congenital diaphragmatic hernia (CDH) using a protocolized approach to management, which includes extracorporeal membrane oxygenation (ECMO) and to present the details of such a management protocol.

METHODS

A retrospective chart review was conducted of the neonatal outcome of near-term (>34 weeks' gestation) newborns with CDH all referred to the Royal Alexandra Hospital either before or after delivery. A protocol was developed that included antenatal assessment, the use of antenatal steroids, planned delivery, use of prophylactic surfactant, pressure limited gentle ventilation, permissive hypercarbia and hypoxia, and venovenous ECMO, if indicated.

RESULTS

Sixty-five infants with CDH were treated from February 1989 through August 1996. Twenty-three infants were inborn, 20 of whom were antenatal referrals. Overall, 51 of the 65 infants survived (78%). Thirteen of the 23 inborn infants survived with conservative management, and 10 required ECMO, of whom, eight were long-term survivors. Thirty-eight infants required ECMO, and 26 survived (68%), whereas there were only two deaths among the 27 conservatively treated infants. Eighteen of 20 inborn infants with an antenatal diagnosis survived, compared with 13 of 21 (62%) outborn infants. An antenatal diagnosis before 25 weeks' gestation was associated with a 60% survival rate. Sixty-three percent of infants whose best postductal PaO2 value before ECMO was less than 100 torr survived, and 7 of 11 infants with a best postductal PaO2 value of less than 50 torr before ECMO survived (64%). The average age at surgery progressively increased over time both for infants who did not require ECMO (1.3 days to 5.8 days; P = .01) and for infants who received ECMO (1.9 days to 8.2 days; P = .016).

CONCLUSIONS

The use of a protocolized management for infants with CDH has been associated with improving outcome in a population at high risk. The components (either separately or combined) of these protocolized approaches need to be tested in prospective trials to determine their true benefit. In addition, there is a need to evaluate prospectively the outcomes of infants with CDH born in ECMO centers compared with those infants born in other tertiary care neonatal units to determine the most appropriate management of the fetus with CDH.

Percutaneous access for venovenous extracorporeal life support in neonates

BACKGROUND

Although percutaneous cannulation has been previously described in adult and pediatric patients older than 3 years, its use in neonates for venovenous extracorporeal life support (ECLS) has not been previously described.

METHODS

Twenty neonates of weight 3.4 +/- 0.6 kg (range, 2.3 to 4.9 kg.) with severe respiratory failure (meconium aspiration syndrome, persistent pulmonary hypertension of the newborn, sepsis) were managed with double-lumen venovenous ECLS. Percutaneous access via the right internal jugular (RIJ) vein with a 12F (n = 13) or 15F (n = 7) double-lumen ECLS cannula was obtained via a modified Seldinger technique. RIJ access was specifically obtained 2 to 3 cm above the clavicle with a 21-gauge needle and a 0.018-in guide wire followed by a technique that allowed insertion of the larger cannula guide wire. Decannulation simply involved removal of the cannula with hemostasis obtained by direct pressure.

RESULTS

Percutaneous cannulation was performed without difficulty in 11 infants. Conversion to an open technique for cannula placement was required in four patients early in our experience because percutaneous access to the RIJ with the 0.018-inch guide wire could not be achieved, and in one neonate because the 15F cannula could not be advanced into the RIJ and resulted in laceration of the vein. Inability to achieve RIJ access also led to use of an "exposure-assisted" percutaneous procedure in four patients later in our experience. Complications included a pneumothorax identified on chest radiograph 18 hours after cannulation in one infant and partial thrombotic occlusion of the cannula requiring a change over a guide wire in another. There were no problems associated with decannulation.

CONCLUSIONS

This is the first description of percutaneous cannulation in neonates for venovenous ECLS. In the authors' early experience, percutaneous access using a 12F double lumen venovenous cannula may be efficiently performed especially in patients >3.0 kg in weight and has the potential for simplifying and reducing the cost of the ECLS technique.

Single needle venovenous extracorporeal membrane oxygenation using a nonocclusive roller pump for rescue in infants and children

In 1993, J.Y. Chevalier described a single needle venovenous extracorporeal membrane oxygenation (ECMO) system using a nonocclusive roller pump and alternating clamps for pulmonary support in neonates. We modified this system to use it in older children as well and for additional indications. Introducing a double raceway and 2 different sizes of tubing sets and performing percutaneous approach, we treated 21 children (age 1 day to 49 months) using this system. Indications for treatment were hypoxia and hypoxic induced myocardial dysfunction resulting from pulmonary failure, sepsis, and congenital defects. Of the children treated for neonatal indications, 7/9 survived. For 2 children ECMO was terminated because of intraventricular hemorrhage (IVH). In the pediatric group 5/7 of the children could be weaned from ECMO, and 2 children died after more than 30 days on ECMO. Two of the children who had been almost completely weaned died later because of therapy withdrawal following a brain death diagnosis. In the cardiac group, 3/5 of the children survived. We conclude that the described system is an effective venovenous ECMO system that reduces invasivity and expenditure.

Preoperative ECMO in congenital cyanotic heart disease using the AREC system

BACKGROUND

In cyanotic congenital heart disease, oxygen delivery is impaired either by reduced pulmonary perfusion or by limited entry of oxygenated blood into the systemic circulation. Additional impairment of oxygen delivery (eg, in pulmonary hypertension) leads to hypoxic cerebral damage. Preoperative extracorporeal membrane oxygenation enables oxygenation in otherwise untreatable cases.

METHODS

In 3 neonates suffering from cyanotic congenital heart disease (1 with tricuspid atresia and 2 with transposition of the great arteries) with arterial desaturation despite application of prostaglandins, balloon atrioseptostomy, and eventually inhaled nitric oxide during intermittent positive-pressure ventilation with an inspired oxygen fraction of 1, oxygenation could only be established by means of preoperative extracorporeal membrane oxygenation. We used a venovenous single-lumen cannula tidal-flow extracorporeal membrane oxygenation system described by Chevalier and associates that has previously been used for extracorporeal lung support. In this system, called AREC (assistence respiratoire extra-corporelle), alternating clamps and a nonocclusive roller pump were used.

RESULTS

All 3 survived.

CONCLUSIONS

We conclude that the AREC system enables sufficient preoperative oxygenation in patients with cyanotic congenital heart disease and hypoxia in spite of all conventional therapeutic means. This provides a stable preoperative condition for elective palliation or correction.

Principles and Practice of Venovenous Extracorporeal Membrane Oxygenation

Over the past several years, the use of venovenous extracorporeal membrane oxygenation (ECMO) has increased. The primary advantage of venovenous (VV) over venoarterial (VA) ECMO is preservation of the carotid artery. Its primary disadvantage is that it does not provide circulatory support. While VV ECMO is technically similar to VA ECMO, clinical application of VV ECMO is quite different from VA ECMO. Recent clinical data show that VV ECMO is safe and effective. The purpose of this review is to discuss these differences between VV and VA ECMO, to review the various forms of VV ECMO, and finally to offer recommendations on the safe clinical use of VV ECMO.

Venovenous extracorporeal membrane oxygenation: the effects of proximal internal jugular cannulation

Venovenous (VV) extracorporeal membrane oxygenation (ECMO) using a double lumen catheter has become an accepted method of providing ECMO support for critically ill newborn infants. In addition, use of the cephalic jugular catheter can provide augmented venous blood flow, potentially prevent increased cerebral venous pressure, maintain cerebral venous blood flow, and increase ECMO oxygen delivery. The authors compared their experience using VV double-lumen (VVDL) ECMO with a cephalic jugular catheter with their previous experience using venoarterial (VA) ECMO. They compared 15 infants who had meconium aspiration syndrome (MAS) and 12 who had congenital diaphragmatic hernia (CDH) treated with VVDL ECMO with a cephalic jugular catheter with the same number of infants with each condition treated with VA ECMO (historical controls). There were no significant differences between the groups with respect to birth weights, oxygen indexes before ECMO, of ECMO flows at 4 and 24 hours. For infants with MAS treated with VVDL ECMO, the overall duration of ECMO support was significantly shorter (63 hours VVDLv 118 hours VA; P = .001), and the average cephalic flow was 33 mL/kg for infants treated with VVDL support. For infants with CDH, there were no differences in any of the variables evaluated, including total duration (100 hours VVDLv 128 hours VA; P = .06 [NS]), and the average cephalic flow was 39 mL/kg for infants treated with VVDL support. The venous oxygen content was significantly lower in infants with MAS treated with VVDL ECMO than for historical controls treated with VA ECMO at 4 hours of ECMO support (15.8 v 16.7; P < or = .05). No other significant differences were noted for any of the calculated oxygen transport variables comparing VVDL with VA ECMO infants with CDH treated with VVDL ECMO were extubated sooner than those treated with VA ECMO (10.3 days VVDL v 15.4 days VA; P = 048). In addition, there was no significant difference in the overall incidence of complications or death. This experience suggests that VVDL ECMO using a cephalic jugular catheter results in shorter ECMO runs and provides support that is comparable to VA ECMO for infants with CDH and MAS while avoiding carotid artery cannulation and ligation.

A comparison of venovenous and venoarterial extracorporeal membrane oxygenation in the treatment of neonatal respiratory failure

OBJECTIVE

To compare the efficacy of venovenous to venoarterial bypass in an unselected cohort of infants with refractory cardiorespiratory failure.

DESIGN

Retrospective cohort analysis.

SETTING

Two tertiary hospitals capable of providing extracorporeal life support for neonates with acute respiratory failure.

PATIENTS

All San Diego Regional Extracorporeal Membrane Oxygenation (ECMO) Program patients treated after the adoption of a policy which eliminated traditional restrictions to venovenous support.

INTERVENTIONS

Venoarterial or venovenous extracorporeal life support.

MEASUREMENTS AND MAIN RESULTS

Fifty-four infants were treated with venovenous bypass; 30 were treated with venoarterial bypass due to unsuccessful placement of the double lumen venovenous catheter or inability to exclude congenital heart disease before cannulation. No patient required conversion from venovenous to venoarterial ECMO. There were no differences in birth weight, gestational age, diagnosis, or pre-ECMO condition in the two groups. Patients who met ECMO criteria early were more likely to be successfully cannulated with a double-lumen venovenous catheter. Severe hemodynamic compromise was present before cannulation in a comparable percentage of venovenous and venoarterial patients. During venovenous bypass, mean Pao2 values were lower but remained in the normoxic range; Paco2 values, ventilatory setting, intravascular volume requirements, inotropic support, and mean duration of ECMO support were not different. The frequency rate of patient and mechanical complications were also comparable, except that the frequency of intravascular thrombosis was significantly lower in patients receiving venovenous ECMO. Survival, the frequency rate of chronic lung disease, and neurodevelopmental outcome were similar in the two groups.

CONCLUSIONS

We conclude that venovenous ECMO using a double-lumen venovenous catheter can provide results comparable with venoarterial bypass without the need for carotid artery ligation in an unselected population of neonatal ECMO candidates. In our experience, reported contraindications to venovenous ECMO did not prove to be valid.

Modern treatment modalities for neonatal and pediatric respiratory failure

BACKGROUND

Respiratory failure secondary to a variety of causes remains a significant cause of morbidity and mortality in the pediatric population. Newer therapies are appearing frequently in an attempt to decrease the number of deaths from this disease state. We briefly review the current literature on some of the newer modalities including: high-frequency ventilation, surfactant, liquid ventilation, and nitric oxide. We then present our experience from the past 11 years in the most invasive, yet successful, therapy for acute respiratory failure-extracorporeal membrane oxygenation (ECMO).

METHODS

Retrospective review of all patients treated with ECMO from September 1983 to December 1994 was undertaken. Data were collected from bedside ECMO flow sheets and the standardized data entry forms submitted to the Extracorporeal Life Support Organization. All statistical analyses were performed using a standard statistical software program.

RESULTS

During the study period, 194 neonates and 47 pediatric patients were treated with ECMO. The survival rate in the neonatal population is 82% and in the pediatric population it is 40%. The neonatal patients required an average of 153 hours of support while the pediatric patients required 220 hours (P = 0.008).

CONCLUSIONS

While the newer treatment modalities discussed may have an important role in treating neonatal and pediatric respiratory failure in the near future, ECMO remains a cornerstone of the modern treatment modalities. Although somewhat invasive, ECMO is effective therapy with increasing survival rates each year.

Neutrophil and cytokine activation with neonatal extracorporeal membrane oxygenation

OBJECTIVE

To determine whether extracorporeal membrane oxygenation (ECMO), like cardiopulmonary bypass, produces systemic inflammatory responses that could potentiate organ injury in infants with respiratory failure.

STUDY DESIGN

We evaluated the effects of neonatal ECMO on neutrophil surface adherence proteins, elastase release, and cytokine levels in blood samples from 15 patients before and during ECMO, and from banked blood and ECMO circuit blood before cannulation. Neutrophil elastase, tumor necrosis factor alpha, and interleukin types 1 beta, 6, and 8 were measured. Chest radiographs were evaluated by a radiologist using a lung injury score in blinded fashion.

RESULTS

Primed ECMO circuit blood, in comparison with patient pre-ECMO blood, demonstrated marked up-regulation of CD11b (mean fluorescence intensity 1660 +/- 109 vs 361 +/- 81; p < 0.001 (mean +/- SEM)), shedding of L-selectin (mean fluorescence intensity 10 +/- 2 vs 89 +/- 38; p < 0.01), and elevated elastase levels (349 +/- 76 vs 154 ng/ml +/- 38; p < 0.001), consistent with neutrophil activation. During ECMO, neutrophil CD11b levels increased but L-selectin was not significantly shed. Concentrations of circulating neutrophil elastase increase significantly during ECMO. Corrected circulating quantities of interleukin-8 also rose significantly, but the responses of tumor necrosis factor alpha and interleukin-1 beta were minimal. Radiographic lung injury scores worsened with the initiation of ECMO (median score: 6 before ECMO vs 11 in first hour of ECMO; p = 0.012), in conjunction with indicators of neutrophil activation.

CONCLUSION

Neonates with respiratory failure have activation of the inflammatory cascade. ECMO incites additional neutrophil and cytokine activation in association with early pulmonary deterioration. Routine leukodepletion of blood for circuit priming to remove activated neutrophils may be beneficial.

Prediction of mortality in neonates with congenital diaphragmatic hernia treated with extracorporeal membrane oxygenation

OBJECTIVE

To determine if data collected by the Extracorporeal Life Support Organization Registry could be used to identify neonates with congenital diaphragmatic hernia who had a > 90% mortality rate, despite the use of extracorporeal membrane oxygenation (ECMO) support.

DESIGN

We retrospectively reviewed data reported to the Extracorporeal Life Support Organization Registry on neonates with congenital diaphragmatic hernia.

PATIENTS

Data regarding 1,089 neonates with congenital diaphragmatic hernia reported to the Extracorporeal Life Support Organization Registry between 1980 and 1992 formed the basis of this study. All of the neonates studied had been treated with ECMO. This patient population includes neonates with right- and left-sided diaphragmatic hernia. This registry does not include neonates with congenital diaphragmatic hernia who were not treated with ECMO.

MEASUREMENTS AND MAIN RESULTS

Of 1,089 neonates with congenital diaphragmatic hernia, 679 (62%) survived. There were no differences between the two groups in gender or in the year they were treated. Survival rate did not significantly increase over the years between 1980 and 1992. When compared with survivors, nonsurvivors were more immature (38 +/- 2 vs. 39 +/- 2 wks; p = .01), had lower birth weights (3.0 +/- 0.5 vs. 3.21 +/- 0.53 kg; p = .001), were more often prenatally diagnosed (42% vs. 32%; p = .03), were cannulated at a younger age (31 +/- 54 vs. 40 +/- 50 hrs; p = .01), and had more severe respiratory compromise (higher peak pressures and PaCO2, lower PaO2 values). Multivariate analysis showed that arterial pH and PaO2 just before ECMO, and birth weight, had the highest discriminant coefficients. By using these variables in a discriminant function (D[fx] = 0.68 x pH + 0.62 x birth weight + 0.29 x PaO2; using standardized coefficients and variables), we could identify neonates who died with a sensitivity of 62%, a specificity of 63%, a positive-predictive value of 50%, and a negative-predictive value of 74%. No single variable or combination of variables yielded better results.

CONCLUSIONS

Although a number of factors identify neonates with diaphragmatic hernia as being at higher risk of dying despite ECMO support, data currently collected by the neonatal Extracorporeal Life Support Organization Registry do not allow clinicians to effectively discriminate nonsurvivors from survivors.