Long-term neurophysiologic outcome after neonatal extracorporeal membrane oxygenation

A Systematic Review of Clinical Outcomes After Carotid Artery Ligation Versus Carotid Artery Reconstruction Following Venoarterial Extracorporeal Membrane Oxygenation in Infants and Children

INTRODUCTION

In pediatric and neonatal populations, the carotid artery is commonly cannulated for venoarterial (VA) extracorporeal membrane oxygenation (ECMO). The decision to ligate (carotid artery ligation [CAL]) versus reconstruct (carotid artery reconstruction [CAR]) the artery at decannulation remains controversial as long-term neurologic outcomes remain unknown. The objective of this study was to summarize current literature on clinical outcomes following CAL and CAR after Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO).

METHODS

PubMed (MEDLINE), Embase, Web of Science, and Cochrane databases were searched using keywords from January 1950 to October 2020. Studies examining clinical outcomes following CAL and CAR for VA-ECMO in patients <18 y of age were included. Prospective and retrospective cohort studies, case series, case-control studies, and case reports were included. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were performed independently by two reviewers. Assessment of risk of bias was performed.

RESULTS

Eighty studies were included and classified into four categories: noncomparative clinical outcomes after CAL (n = 23, 28.8%), noncomparative clinical outcomes after CAR (n = 12, 15.0%), comparative clinical outcomes after CAL and/or CAR (n = 28, 35.0%), and case reports of clinical outcomes after CAL and/or CAR (n = 17, 21.3%). Follow-up ranged from 0 to 11 y. CAR patency rates ranged from 44 to 100%. There was no substantial evidence supporting an association between CAL versus CAR and short-term neurologic outcomes.

CONCLUSIONS

Studies evaluating outcomes after CAL versus CAR for VA-ECMO are heterogeneous with limited generalizability. Further studies are needed to evaluate long-term consequences of CAL versus CAR, especially as the first survivors of pediatric/neonatal ECMO approach an age of increased risk of carotid stenosis and stroke.

Characteristics of Neonates with Cardiopulmonary Disease Who Experience Seizures: A Multicenter Study

OBJECTIVE

To compare key seizure and outcome characteristics between neonates with and without cardiopulmonary disease.

STUDY DESIGN

The Neonatal Seizure Registry is a multicenter, prospectively acquired cohort of neonates with clinical or electroencephalographic (EEG)-confirmed seizures. Cardiopulmonary disease was defined as congenital heart disease, congenital diaphragmatic hernia, and exposure to extracorporeal membrane oxygenation. We assessed continuous EEG monitoring strategy, seizure characteristics, seizure management, and outcomes for neonates with and without cardiopulmonary disease.

RESULTS

We evaluated 83 neonates with cardiopulmonary disease and 271 neonates without cardiopulmonary disease. Neonates with cardiopulmonary disease were more likely to have EEG-only seizures (40% vs 21%, P < .001) and experience their first seizure later than those without cardiopulmonary disease (174 vs 21 hours of age, P < .001), but they had similar seizure exposure (many-recurrent electrographic seizures 39% vs 43%, P = .27). Phenobarbital was the primary initial antiseizure medication for both groups (90%), and both groups had similarly high rates of incomplete response to initial antiseizure medication administration (66% vs 68%, P = .75). Neonates with cardiopulmonary disease were discharged from the hospital later (hazard ratio 0.34, 95% CI 0.25-0.45, P < .001), although rates of in-hospital mortality were similar between the groups (hazard ratio 1.13, 95% CI 0.66-1.94, P = .64).

CONCLUSION

Neonates with and without cardiopulmonary disease had a similarly high seizure exposure, but neonates with cardiopulmonary disease were more likely to experience EEG-only seizures and had seizure onset later in the clinical course. Phenobarbital was the most common seizure treatment, but seizures were often refractory to initial antiseizure medication. These data support guidelines recommending continuous EEG in neonates with cardiopulmonary disease and indicate a need for optimized therapeutic strategies.

ECMO in neonates: The association between cerebral hemodynamics with neurological function

Extracorporeal membrane oxygenation (ECMO) is a superior life support technology, commonly employed in critical patients with severe respiratory or hemodynamic failure to provide effective respiratory and circulatory support, which is especially recommended for the treatment of critical neonates. However, the vascular management of neonates with veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is still under controversy. Reconstruction or ligation for the right common carotid artery (RCCA) after ECMO is inconclusive. This review summarized the existed studies on hemodynamics and neurological function after vascular ligation or reconstruction hoping to provide better strategies for vessel management in newborns after ECMO. After reconstruction, the right cerebral blood flow can increase immediately, and the normal blood supply can be restored rapidly. But the reconstructed vessel may be occluded and stenotic in long-term follow-ups. Ligation may cause lateralization damage, but there could be no significant effect owing to the establishment of collateral circulation. The completion of the circle of Willis, the congenital anomalies of cerebral or cervical vasculature, the duration of ECMO, and the vascular condition at the site of arterial catheterization should be assessed carefully before making the decision. It is also necessary to follow up on the reconstructed vessel sustainability, and the association between cerebral hemodynamics and neurological function requires further large-scale multi-center studies.

ECMO in neonates: neuroimaging findings and outcome

Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for newborns with severe but reversible respiratory failure. Although ECMO has significantly improved survival, it is associated with substantial complications, of which intracranial injuries are the most important. These injuries consist of hemorrhagic and non-hemorrhagic, ischemic lesions. Different from the classical presentation of hemorrhages in preterm infants, hemorrhages in ECMO-treated newborns are mainly parenchymal and with a high percentage in the posterior fossa area. There are conflicting data on the predominant occurrence of cerebral lesions in the right hemisphere. The existence of intracerebral injuries and the classification of its severity are the major predictors of neurodevelopmental outcome. This section will discuss the known data on intracranial injury in the ECMO population and the effect of ECMO on the brain.

Neurodevelopmental and neurofunctional outcomes in children with congenital diaphragmatic hernia

The objective of this review was to provide a critical overview of our current understanding on the neurocognitive, neuromotor, and neurobehavioral development in congenital diaphragmatic hernia (CDH) patients, focusing on three interrelated clinical issues: (1) comprehensive outcome studies, (2) characterization of important predictors of adverse outcome, and (3) the pathophysiological mechanism contributing to neurodevelopmental disabilities in infants with CDH. Improved survival for CDH has led to an increasing focus on longer-term outcomes. Neurodevelopmental dysfunction has been recognized as the most common and potentially most disabling outcome of CDH and its treatment. While increased neuromotor dysfunction is a common problem during infancy, behavioral problems, hearing impairment and quality of life related issues are frequently found in older children and adolescence. Intelligence appears to be in the low normal range. Patient and disease specific predictors of adverse neurodevelopmental outcome have been defined. Imaging studies have revealed a high incidence of structural brain abnormalities. An improved understanding of the pathophysiological pathways and the neurodevelopmental consequences will allow earlier and possibly more targeted therapeutic interventions. Continuous assessment and follow-up as provided by an interdisciplinary team of medical, surgical and developmental specialists should become standard of care for all CDH children to identify and treat morbidities before additional disabilities evolve and to reduce adverse outcomes.

The long-term follow-up of patients with a congenital diaphragmatic hernia: a broad spectrum of morbidity

Congenital diaphragmatic hernia (CDH) is a life-threatening anomaly with a mortality rate of approximately 40-50%, depending on case selection. It has been suggested that new therapeutic modalities such as nitric oxide (NO), high frequency oxygenation (HFO) and extracorporal membrane oxygenation (ECMO) might decrease mortality associated with pulmonary hypertension and the sequelae of artificial ventilation. When these new therapies indeed prove to be beneficial, a larger number of children with severe forms of CDH might survive, resulting in an increase of CDH-associated complications and/or consequences. In follow-up studies of infants born with CDH, many complications including pulmonary damage, cardiovascular disease, gastro-intestinal disease, failure to thrive, neurocognitive defects and musculoskeletal abnormalities have been described. Long-term pulmonary morbidity in CDH consists of obstructive and restrictive lung function impairments due to altered lung structure and prolonged ventilatory support. CDH has also been associated with persistent pulmonary vascular abnormalities, resulting in pulmonary hypertension in the neonatal period. Long-term consequences of pulmonary hypertension are unknown. Gastro-esophageal reflux disease (GERD) is also an important contributor to overall morbidity, although the underlying mechanism has not been fully understood yet. In adult CDH survivors incidence of esophagitis is high and even Barrett's esophagus may ensue. Yet, in many CDH patients a clinical history compatible with GERD seems to be lacking, which may result in missing patients with pathologic reflux disease. Prolonged unrecognized GERD may eventually result in failure to thrive. This has been found in many young CDH patients, which may also be caused by insufficient intake due to oral aversion and increased caloric requirements due to pulmonary morbidity. Neurological outcome is determined by an increased risk of perinatal and neonatal hypoxemia in the first days of life of CDH patients. In patients treated with ECMO, the incidence of neurological deficits is even higher, probably reflecting more severe hypoxemia and the risk of ECMO associated complications. Many studies have addressed the substantial impact of the health problems described above, on the overall well-being of CDH patients, but most of them concentrate on the first years after repair and only a few studies focus on the health-related quality of life in CDH patients. Considering the scattered data indicating substantial morbidity in long-term survivors of CDH, follow-up studies that systematically assess long-term sequelae are mandatory. Based on such studies a more focused approach for routine follow-up programs may be established.

Systemic hyperthermia induces ischemic brain injury in neonatal mice with ligated carotid artery and jugular vein

Postnatal d 7 (p7) or p12 mice had their right carotid artery (CA) and jugular vein (JV) ligated to mimic veno-arterial (VA) access for extracorporeal membrane oxygenation (ECMO). At p9-11 (early) or p19-21 (late) mice were exposed to hyperthermia or normothermia followed by assessment of neuropathological injury score. In separate cohorts of mice, cerebral and peripheral blood flow (CBF, PBF) and cerebral ATP content was measured. Hyperthermia resulted in ischemic brain injury in 57% and 77% of mice subjected to early or late hyperthermia, respectively. Isolated CA+JV ligation induced minimal injury (score 0.47 +/- 0.34) in 2/8 mice from the late normothermia group. No cerebral injury was detected in mice subjected to early normothermia. In 3/19 shams (2/10 early, 1/9 late) hyperthermia induced a subtle (score, 0.6 +/- 0.27) injury in the ipsilateral to the site of surgery cortex. CBF and PBF increased in response to hyperthermia in all mice. The rise in CBF was significantly attenuated in the "ligated" versus intact hemisphere, which was associated with a profound depletion of ATP content. Systemic hyperthermia induces ischemic brain injury in mice with ligated CA+JV. We speculate that hyperthermia/fever can be a potential risk factor for brain injury in infants treated with VA ECMO.

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.

Quantitative Electroencephalography Values of Neonates During and After Venoarterial Extracorporeal Membrane Oxygenation and Permanent Ligation of Right Common Carotid Artery

Venoarterial extracorporeal membrane oxygenation (ECMO) in neonates commonly needs neck vessel cannulation leading to ligation of right common carotid artery (RCCA) in some cases. Quantitative electroencephalography (EEG) measurements provide reproducible data of cerebral function. The aim of this case-control study was to test whether ligation of the RCCA results in EEG changes after ECMO weaning. Ten mechanically ventilated neonates not treated with ECMO were eligible as control patients. Seven ECMO patients receiving similar sedoanalgesia were investigated during and after ECMO and RCCA ligation. Dominant frequency, absolute alpha, theta, delta, and total powers of right and left frontocentral and temporooccipital derivations were calculated. Dominant frequency did not differ among groups. Power was found to be significantly decreased in all frequency bands during ECMO. After weaning from ECMO, EEG differences between the ECMO and control groups disappeared in spite of permanent RCCA ligation. It is concluded that ligation of the RCCA per se does not result in quantitative EEG changes.

The effect of extracorporeal life support on the brain: a focus on ECMO

Extracorporeal membrane oxygenation (ECMO) therapy has significantly improved outcome in the newborn, pediatric, and adult patient in respiratory and cardiac failure. Despite this therapy providing a life-saving technology, the morbidity in patients treated with ECMO therapy is primarily related to neurologic alterations and not pulmonary findings. For ECMO, this is not unexpected since most patients are being placed on ECMO support because of severe hypoxemia, with ECMO being considered a rescue therapy for respiratory failure in most instances. As use of ECMO becomes common place for infants and children in respiratory failure, our investigations into the outcome of these children must focus not only on survival versus nonsurvival, but on the causes of morbidity in this population. A further understanding of factors associated with morbidity may allow us to alter techniques used in extracorporeal life support (ECLS), hopefully to improve our long-term outcome in this population, while allowing us to expand use of these technologies to other populations such as the premature infant. This article will focus on the effect of ECMO on the brain, with the following chapter by Dr. Richard Jonas outlining the effect of cardiopulmonary bypass on the brain.

Oxygenation and hemodynamics in left and right cerebral hemispheres during induction of veno-arterial extracorporeal membrane oxygenation

OBJECTIVE

Oxygenation and hemodynamics in the left and right cerebral hemispheres were measured during induction of veno-arterial extracorporeal membrane oxygenation (VA-ECMO).

STUDY DESIGN

Using near infrared spectrophotometry, effects of right common carotid artery (RCCA) and right internal jugular vein (RIJV) ligation and start of VA-ECMO on concentrations of oxyhemoglobin, deoxyhemoglobin, and cerebral blood volume (CBV) were evaluated in 10 newborn infants. Mean cerebral blood flow velocity (CBFV) in the major cerebral arteries was compared before and after the start of VA-ECMO (pulsed Doppler ultrasonography).

RESULTS

RCCA ligation caused a decrease in oxyhemoglobin concentration and an increase in deoxyhemoglobin concentration. RIJV ligation caused no changes. Sixty minutes after the start of VA-ECMO, oxyhemoglobin concentration and CBV had increased, and deoxyhemoglobin concentration had decreased. There were no differences between the hemispheres. Mean CBFV had increased in the left internal carotid artery, and it increased equally in both middle cerebral arteries. Flow direction was reversed in the right internal carotid artery. Three patients had asymmetric cerebral lesions, not related to differences in the measurements between the cerebral hemispheres.

CONCLUSION

The initiation of VA-ECMO causes changes in cerebral oxygenation and hemodynamics but without a difference in effect on left and right cerebral hemispheres.

Persistent pulmonary hypertension of the newborn. Rational therapy based on pathophysiology

Persistent pulmonary hypertension of the newborn is a common disorder among near-term gestation newborns. Persistent pulmonary hypertension of the newborn is characterized by hypoxemia that is frequently refractory to conventional management. This article describes the pathophysiologic basis of the disorder and the current therapy that is based on this knowledge.

Extracorporeal membrane oxygenation 2001. The odyssey continues

Extracorporeal membrane oxygenation was established as a standard of care by demonstrating its ability to save lives in moribund infants. The designs of early studies provided no living cohorts of similarly ill patients by which to measure accurately other (and perhaps to many more important) outcomes of interest: long-term neurodevelopmental outcomes or cost. Prospective cohort studies of neurodevelopmental outcomes post-ECMO demonstrate: (1) because ECMO, as used, saves lives, there will be an increase in the absolute number of handicapped children surviving; (2) there is little evidence that ECMO creates a relative increase in the percent of handicapped children surviving severe respiratory failure. The high direct costs of an ECMO program are measured and well publicized. When such costs are compared with similar therapies in other fields (in such terms as cost per survivor), the cost of ECMO does not seem to be an outlier. Trials of newer therapies, such as iNO, show the capacity to decrease the use of ECMO but have failed to demonstrate either cost-effectiveness or better long-term outcomes. It has not been shown that either society or individual patients have benefited from the decreased need for ECMO.

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.

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.

Balloon aortic valvuloplasty in a 1,600-gram infant

We present a 1,600 g infant who underwent successful balloon aortic valvuloplasty from the right carotid artery approach. A simple technique to facilitate access to the left ventricle and expedite the procedure is described. Issues unique to performing balloon aortic valvuloplasty on such a small child are discussed.

Five-year follow-up of neonates with reconstructed right common carotid arteries after extracorporeal membrane oxygenation

OBJECTIVE

Serial Doppler ultrasonography and long-term neurodevelopmental follow-up outcomes were evaluated prospectively in neonates whose right common carotid artery (RCCA) was reconstructed after extracorporeal membrane oxygenation (ECMO).

METHODS

Children with RCCA reconstruction (n = 34) were monitored for 3.5 to 4.5 years by Doppler ultrasonography for arterial patency, and 28 had IQ testing by 5 years. A comparison group consisted of 35 infants who had RCCA ligation after ECMO. Neonatal electroencephalograms and computed tomography/magnetic resonance imaging scans were also compared.

RESULTS

Reconstructions were successful (<50% RCCA stenosis by Doppler ultrasonography) in 26 (76%) of 34 children, 3 (9%) had >/=50% stenosis, and 5 (15%) had occlusion. No significant differences were seen between reconstructed and ligated groups in neonatal complications or ECMO courses. Occurrence of marked neonatal electroencephalographic abnormalities did not differ between groups. Abnormalities on computed tomography/magnetic resonance imaging scans (4 of 31 vs 11 of 29, P =.025) and cerebral palsy (0 of 34 vs 5 of 35, P =.054) were more common in infants with RCCA ligation. No differences were seen in developmental or IQ scores between the 2 groups, and 4 in each group had cognitive handicaps (at least 1 IQ score <70).

CONCLUSIONS

Most RCCA reconstructions remained patent, with 24% showing significant stenosis or occlusion. Compared with a historical control group, patients with RCCA reconstruction had fewer brain scan abnormalities and tended to be less likely to have cerebral palsy. RCCA reconstruction after venoarterial ECMO may improve outcome.

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.

Extracorporeal membrane oxygenation causing asymmetric vasculopathy in neonatal infants

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a form of cardiopulmonary bypass therapy used in term or near-term infants with severe cardiorespiratory disorders not responsive to conventional intensive care interventions. An ECMO-associated retinal vasculopathy has been described with little reference to the specific condition of the patient. We examined the eyes of 91 infants who underwent ECMO treatment. An assessment was made of the following: (1) when retinal changes occurred, (2) whether there was a particular systemic disorder or ECMO approach associated with these retinal findings, and (3) whether there may be ocular sequelae from this development.

METHODS

Ninety-one neonates were treated with ECMO for meconium aspiration syndrome (MAS), primary persistent pulmonary hypertension of the newborn, sepsis, congenital diaphragmatic hernia (CDH), respiratory distress syndrome (RDS), and blood aspiration. Venoarterial bypass was performed in 73 patients. The remaining 18 patients underwent venovenous bypass. Ophthalmologic examinations were performed during bypass in 6 infants and within 3 weeks of ECMO in the remainder.

RESULTS

Asymmetric retinopathy (left eye > right eye) was discovered in six infants with CDH and in one infant with RDS within a 2-week period after bypass, demonstrating venous tortuosity with or without intraretinal hemorrhages. One infant treated for MAS had a left eye intraretinal hemorrhage only. All patients with the noted retinal changes underwent venoarterial cannulation. Six of 9 patients with CDH had retinal findings noted compared with 1 of 10 patients with RDS and 1 of 35 patients with MAS.

CONCLUSION

Because we were able to examine infants while they were receiving ECMO or shortly after termination of bypass, asymmetric vasculopathy was found in a greater percentage of our patients compared with a similar large case series. ECMO-associated retinal vasculopathy appeared to disproportionately occur in those patients with CDH who underwent venoarterial bypass. Further study of retinal vascular changes in patients with CDH should be performed to assess long-term effects.

Hearing loss associated with neonatal ECMO: a clinical investigation

To answer the question as to the prevalence of sensori-neural hearing loss (SNHL) among neonates receiving ECMO, a retrospective chart review was conducted on 198 infants having surgery between November 1987 and January 1995. One hundred fifty-seven (79.7%) survived. One hundred thirty infants met our criteria of having a pre-discharge auditory brainstem evoked response (ABR) test and at least one follow-up behavioral audiologic examination. Strict criteria were set for normal hearing on both the ABR and follow-up examinations. Only follow-up results are reported. At the time of the most recent follow-up examination, two children could not be adequately studied, 106 exhibited normal hearing, 21 (16%) exhibited either unilateral or bilateral conductive hearing loss and three (2.3%) exhibited unilateral or bilateral SNHL. Only one child is using amplification. With the largest sample size to date, we found a lower prevalence of SNHL after ECMO than has been previously noted in the literature. Although the prevalence of hearing loss is low, the post-ECMO group of infants must be considered at risk for hearing loss. The prevalence of hearing loss cannot be based solely on a pre-discharge ABR, i.e. ongoing follow-up testing is necessary.

Purine metabolism and inhibition of xanthine oxidase in severely hypoxic neonates going onto extracorporeal membrane oxygenation

The effect of allopurinol to inhibit purine metabolism via the xanthine oxidase pathway in neonates with severe, progressive hypoxemia during rescue and reperfusion with extracorporeal membrane oxygenation (ECMO) was examined. Twenty-five term infants meeting ECMO criteria were randomized in a double-blinded, placebo-controlled trial. Fourteen did not receive allopurinol, whereas 11 were treated with 10 mg/kg after meeting criteria and before cannulation, in addition to a 20-mg/kg priming dose to the ECMO circuit. Infant plasma samples before cannulation, and at 15, 30, 60, and 90 min, and 3, 6, 9, and 12 h on bypass were analyzed (HPLC) for allopurinol, oxypurinol, hypoxanthine, xanthine, and uric acid concentrations. Urine samples were similarly evaluated for purine excretion. Hypoxanthine concentrations in isolated blood-primed ECMO circuits were separately measured. Hypoxanthine, xanthine, and uric acid levels were similar in both groups before ECMO. Hypoxanthine was higher in allopurinol-treated infants during the time of bypass studied (p = 0.022). Xanthine was also elevated (p < 0.001), and uric acid was decreased (p = 0.005) in infants receiving allopurinol. Similarly, urinary elimination of xanthine increased (p < 0.001), and of uric acid decreased (p = 0.04) in treated infants. No allopurinol toxicity was observed. Hypoxanthine concentrations were significantly higher in isolated ECMO circuits and increased over time during bypass (p < 0.001). This study demonstrates that allopurinol given before cannulation for and during ECMO significantly inhibits purine degradation and uric acid production, and may reduce the production of oxygen free radicals during reoxygenation and reperfusion of hypoxic neonates recovered on bypass.

Adaptation of an ECMO team in the era of successful alternative therapies for neonatal pulmonary failure

Neonates with persistent pulmonary hypertension show severe hypoxemia that requires a variety of therapeutic modalities. When patients do not respond to conventional medical management that includes hyperventilation, inotropic support, and vasodilating agents, treatment with extracorporeal membrane oxygenation (ECMO) may be used. More recently, high-frequency oscillatory ventilation and nitric oxide inhalation have been used in these infants and have impacted the need for ECMO. In light of these changes in therapy, the authors reviewed the 6-year clinical experience of an ECMO team to assess trends in patient population and outcome and document adaptation of the medical professionals to a new treatment era. Between 1988 and 1993, 88 neonates who met the institutional criteria were placed on venoarterial ECMO. Oscillatory ventilation was locally introduced in 1991 and nitric oxide treatment in 1992. Patient outcomes for the 1988 to 1990 period were compared with those for 1991 to 1993. Analyses included indication for ECMO therapy, length and complexity of the run, length of hospital stay, and cost of patient care. During the first 3 years, 65 patients were placed on ECMO, compared with 23 patients during the 3 years after introduction of oscillatory ventilation and nitric oxide therapy (P < .001). The length of ECMO therapy increased from a mean of 128 hours to 190 hours (P = .005), and the average hospital stay, likewise, increased from 27 days to 42 days. The total cost of care increased by approximately $40,000 per patient.(ABSTRACT TRUNCATED AT 250 WORDS)

MRI, MRA, and neurodevelopmental outcome following neonatal ECMO

Cranial magnetic resonance imaging (MRI) of 31 newborn infants treated with venoarterial cardiopulmonary bypass for severe but reversible respiratory failure, revealed major focal parenchymal lesions in 7 of 31 infants (23%) and demonstrated abnormal enlargement of extra-axial and ventricular cerebrospinal fluid spaces in 16 of 31 (51%). No preferential left versus right lateralization of focal injury was observed in conjunction with right common carotid artery and jugular vein ligation. No statistically significant relationships were found between major brain lesions on MRI scans and the clinical characteristics of the pre-extracorporeal membrane oxygenation (ECMO), ECMO, and post-ECMO course. Major focal brain lesions were significantly associated with an asymmetric cerebrovascular response to carotid ligation of the right versus left middle cerebral arteries as detected by magnetic resonance angiography (P < .05). Enlarged cerebrospinal fluid spaces were not significantly related to the presence of parenchymal MRI lesions, but were associated with lower Bayley neurodevelopmental scores for mental (MDI) and psychomotor evaluations (PDI) at 6 and 12 months (P < .05). It is concluded that asymmetries of cerebral vascular adaptation detected by magnetic resonance angiography after ECMO may be associated with major brain lesions revealed by MRI. Thereafter, the presence of enlarged cerebrospinal fluid spaces on MRI is associated with a poor shortterm developmental outcome.

Median nerve somatosensory evoked potentials in children receiving ECMO

Somatosensory evoked potentials (SEPs) were recorded from 11 patients receiving venoarterial extracorporeal membrane oxygenation (ECMO). Cortical responses recorded from the right and left hemispheres were compared to those from 2 other groups of children who were not receiving ECMO. One group consisted of 99 brain-injured patients, while the other consisted of a group of 17 neurologically normal controls. SEP responses from each hemisphere were categorized into 3 grades based on the N20 component--normal latency, abnormal (latency increased > 3 S.D.), or absent. For ECMO patients, 15% of tests disclosed a disagreement between the right and left hemispheres, while 27% of tests from the control group revealed a disagreement between the right and left hemispheres. SEPs were normal over the right hemisphere in 9 patients. Central conduction times obtained from the right and left hemispheres were similar in ECMO patients and were not different from those recorded from a group of patients suffering hypoxic-ischemic injuries and a group of normal controls who did not receive ECMO. The results of this pilot study suggest that SEPs may be employed to evaluate ECMO patients as they are in other brain-injured patients.

Predictive value of neonatal electroencephalograms before and during extracorporeal membrane oxygenation

We studied the prognostic significance of electroencephalograms recorded serially at 2- to 4-day intervals during the acute neonatal course of 119 near-term infants with severe respiratory failure treated by venoarterial extracorporeal membrane oxygenation (ECMO). A poor prognosis was defined as early death (n = 27), an abnormally low developmental assessment score (n = 14), or cerebral palsy (n = 14) at 12 to 45 months of age. The only electroencephalographic abnormalities that were significantly related to a poor prognosis were burst suppression (B-S) and electrographic seizure (ES). The 30 infants with two or more recordings of B-S or ES, when compared with the 58 neonates without such electroencephalographic abnormalities, had an odds ratio for a poor prognosis of 6.6 (95% confidence limits, 2.2 to 20.2). The 31 infants with a single ES or B-S recording did not have a significantly increased risk for a poor prognosis. Cardiopulmonary resuscitation immediately before ECMO (n = 8) and the lowest systolic blood pressure before or during ECMO were significantly related to the occurrence of ES or B-S recordings. There was no significant predilection of ES for either cerebral hemisphere. We conclude that in near-term neonates with respiratory failure, serial electroencephalographic recordings are of predictive value, and may facilitate clinical care including the decision to initiate or to continue ECMO.

Right common carotid artery reconstruction after extracorporeal membrane oxygenation: vascular imaging, cerebral circulation, electroencephalographic, and neurodevelopmental correlates to recovery

OBJECTIVE

Right common carotid artery (RCCA) ligation after extracorporeal membrane oxygenation by venoarterial bypass may contribute to lateralized cerebral injury. Reconstruction of this artery after extracorporeal membrane oxygenation has proved feasible but has not been evaluated for neurologic outcome in any substantial series of infants.

METHODS

We evaluated RCCA reconstruction in 47 infants treated with ECMO and compared their cerebrovascular and neuroanatomic imaging findings, electroencephalograms, and developmental outcomes with those of 93 infants who had no reconstruction. SUMMARY RESULTS: Color Doppler blood flow imaging revealed that carotid artery patency was usually obtained after RCCA reconstruction. Right internal carotid and bilateral anterior and middle cerebral arterial blood flow velocities were generally higher, and were more symmetrically distributed in infants with reconstructed RCCA. Electroencephalography did not disclose an increased risk of deterioration or marked abnormalities in infants after reconstruction, nor were neuroimaging findings consistent with an increased number of either focal or generalized abnormalities. Neurodevelopmental follow-up revealed no differences in the incidence of delays between those with a reconstructed RCCA and those with a ligated RCCA during the first year of life.

CONCLUSIONS

Reconstruction of the RCCA after extracorporeal membrane oxygenation may facilitate normal distribution of cerebral blood flow through the circle of Willis, and may augment both left and right middle cerebral artery blood flow immediately after decannulation. The long-term consequences of either ligation or reconstruction of the RCCA will require careful scrutiny, however, before either course is recommended routinely.

Developmental outcome of infants treated with extracorporeal membrane oxygenation (ECMO) in the neonatal period: is the evidence all in?

The North American literature was reviewed regarding the developmental outcome of infants treated with ECMO therapy versus those infants who received conventional medical therapy for treatment of persistent pulmonary hypertension of the newborn. The literature reviewed included all ECMO follow-up investigations published in medical journals cited in CD-ROM between January 1980 and July 1992, as well as abstracts presented at the Society for Pediatric Research 1990-1992. The literature was examined with respect to the incidence, prevalence and nature of morbidity, with particular attention paid to the neuroevelopmental domains assessed, test measures used, age at assessment and criteria for normal and abnormal outcome. Rough comparison of the published outcome statistics for the cohorts of infants who received neonatal ECMO therapy or conventional medical therapy (CMT) suggest equivalent amounts of morbidity within the first few years of life. Without appropriate systematic comparison at the same ages on the same measures and in infants with equivalent severity of illness, the current observations remain tentative at best. Longitudinal investigations are needed in order to identify specific medical and developmental markers in infancy of good and poor long-term outcome in this population, together with comparisons of outcome in the group treated with ECMO versus the group treated with CMT. Fine-grained, sensitive measures must be employed that record transient or permanent delays and/or qualitative deficits in specific skills.

Extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation has now evolved into standard therapy for patients unresponsive to conventional ventilatory and pharmacological support. This article presents a clinical review of extracorporeal life support and its application to neonatal and pediatric patients as well as children requiring circulatory support after open heart surgery.

Electroencephalographic, neuroradiologic, and neurodevelopmental studies in infants with subclavian steal during ECMO

Color Doppler imaging revealed a subclavian steal--retrograde flow in the right vertebral artery which shunted blood from the brain's posterior circulation to the right arm via the subclavian artery--in 17 of 54 infants (31%) during extracorporeal membrane oxygenation (ECMO); right vertebral artery flow returned to antegrade after ECMO and removal of the right common carotid arterial cannula. When subjects with and without a subclavian steal were compared, there were no statistically significant differences in mortality; in the results of neonatal electroencephalograms, cranial ultrasound studies, or computed tomography studies; or in early neurological development. Blood flow patterns and peak systolic velocities in the circle of Willis, middle cerebral arteries, internal carotid arteries, and basilar artery were similar in both groups during ECMO; blood flow velocity in the middle cerebral arteries was slightly but significantly lower on the right than the left in both groups. Our results indicate that increased flow in the left vertebral artery adequately compensated for the effect of a subclavian steal on the basilar and cerebral circulation. The moderate to marked neonatal electroencephalographic abnormalities commonly occurring during ECMO and the approximately 20% incidence of neurodevelopmental deficits among ECMO survivors remain largely unexplained.

Utility of serial EEGs in neonates during extracorporeal membrane oxygenation

We found electroencephalographic (EEG) studies to be useful for monitoring cerebral function, for confirming seizure activity, and for limited prediction of short-term outcome in 145 neonates who required extra-corporeal membrane oxygenation (ECMO) of reversible respiratory failure. The EEG tracings were classified as normal or as mildly, moderately, or markedly abnormal; abnormal recordings were further classified as focal, diffuse, or predominantly lateralized. A significant decrease in frequency and degree of EEG abnormalities was observed in recordings obtained after ECMO compared to those obtained prior to (P = .001) or during ECMO (P = .001). There was no significant increase in marked EEG abnormalities when recordings obtained before and during ECMO were compared (P = 0.41). Of 11 infants with electrographic seizures during ECMO, 7 (64%) either died during their nursery courses or were developmentally handicapped at age 1 year which is a significantly greater adverse outcome than that observed in infants without EEG seizure activity (P less than .003). No consistently lateralized EEG abnormalities were observed during or after ECMO when compared to tracings obtained before cannulation of the right common carotid artery. There was no acute change in EEG rhythm or amplitude over the right cerebral hemisphere during right common carotid artery cannulation. Our observations support the value of serial EEG in the assessment of cerebral function in critically ill infants undergoing ECMO. They further suggest that, in this patient population, cannulation of the right common carotid artery is a safe procedure that does not result in lateralized abnormalities of cerebral electrical activity.

Significance of seizures associated with extracorporeal membrane oxygenation

We previously reported a predominance of left focal motor seizures in infants receiving extracorporeal membrane oxygenation (ECMO), raising concerns about possible ischemia resulting from the right common carotid artery ligation. We therefore evaluated the neurologic and psychologic outcome at 2 years of age of all infants with ECMO-related seizures. Although 8 of 12 infants had left focal seizures in infancy, there was no lateralization of motor findings at 2 years of age; left hemiparesis was present in three of the infants and right hemiparesis in three. The developmental quotient was normal in 6 of 12 infants, low-average in three, borderline in two, and in the mentally handicapped range in one. We conclude that any ischemia resulting from carotid ligation is not great enough to produce long-term lateralizing findings but that seizures during ECMO are a risk factor for later cerebral palsy or developmental delay.

Carotid artery reconstruction following neonatal extracorporeal membrane oxygenation

Although reconstruction of the right common carotid artery (RCCA) in neonatal extracorporeal membrane oxygenation (ECMO) patients is intuitively attractive, there is little known about prolonged arterial cannulation and how it may affect subsequent vascular repair. A histological study of RCCA segments from neonatal ECMO patients was performed, so that cannulation technique and catheter design could be optimized before proceeding with arterial reconstruction. Circumferential transmural necrosis (CTN) was found in 25 of 31 (80%) arteriotomy specimens in comparison with 2 of 9 (20%) more proximal carotid specimens; the remaining specimens in each group demonstrated either focal subintimal or focal transmural necrosis. CTN was more common in patients with longer ECMO runs (96 +/- 5.9 versus 75 +/- 5.6 hours, P = .009; arteriotomy site), but was independent of cannula size, birthweight, and gestational age. Eleven patients have undergone RCCA reconstruction. Doppler flow studies at 4 to 7 months of follow-up in five patients demonstrated slightly higher right-sided versus left-sided peak systolic, end-diastolic, and mean flow velocities. No neurological or developmental problems could be attributed to vascular reconstruction. In conclusion, RCCA reconstruction is technically feasible, but due to the high prevalence of CTN at the arteriotomy site, excision of this segment is recommended at the time of arterial repair.

Carotid reconstruction in the neonate following ECMO

Permanent ligation of the carotid artery remains a major objection to the use of extra corporeal membrane oxygenation (ECMO) in infants with severe cardiorespiratory disorders. Because reconstruction of the carotid artery is highly desirable, we began a study to evaluate the feasibility and risks of carotid artery repair following decannulation. All infants placed on ECMO from December 1988 to January 1990 were evaluated for carotid artery reconstruction. During this period 18 infants underwent carotid reconstruction and 8 infants were deemed unsuitable candidates. Patency of the right common carotid artery was demonstrated in 14 of the 18 infants with good bilateral anterior and middle cerebral artery flow. Seven infants have had MRA evaluation at 6 months and have demonstrated no significant change from their discharge study. These preliminary findings suggest that carotid reconstruction can be performed safely with no apparent morbidity in the majority of infants placed on ECMO, but long-term follow-up data concerning patency rate and neurological status must be obtained before this technique is applied to all infants with this problem.