Utility of serial EEGs in neonates during extracorporeal membrane oxygenation

Neonatal seizures during extra corporeal membrane oxygenation support

To evaluate EEG monitoring during neonatal ECMO and to identify any correlations between seizure detection to abnormal neuroimaging. Eight-year, service evaluation of neonates who received at least one continuous EEG (cEEG) whilst on ECMO at Great Ormond Street Hospital. Pearson's chi-square test and multivariate logistic regression analysis were used to assess clinical and EEG variables association with seizures and neuroimaging findings. Fifty-seven neonates were studied; 57 cEEG recordings were reviewed. The incidence of seizures was 33% (19/57); of these 74% (14/19) were electrographic-only. The incidence of status epilepticus was 42%, (8/19 with 6 neonates having electrographic-only status and 2 electro-clinical status. Seizures were detected within an hour of recording in 84%, (16/19). The overall mortality rate was 39% (22/57). Seizure detection was strongly associated with female gender (OR 4.8, 95% CI: 1.1-20.4, p = 0.03), abnormal EEG background activity (OR 2.8, 95% CI: 1.1-7.4, p = 0.03) and abnormal EEG focal features (OR 23.6, 95% CI: 5.4-103.9, p = 0.001). There was a strong association between the presence of seizures and abnormal neuroimaging findings (OR 10.9, 95% CI: 2.8-41.9, p = 0.001). Neonates were highly likely to have abnormal neuroimaging findings in the presence of severely abnormal background EEG (OR 9.5, 95% CI 1.7-52.02, p = 0.01) and focal EEG abnormalities (OR 6.35, 95% CI 1.97-20.5, p = 0.002)Conclusion: The study highlights the importance of cEEG in neonates undergoing ECMO. An association between seizure detection and abnormal neuroimaging findings was described. What is Known: • Patients on ECMO are at a higher risk of seiures. • Continuous EEG monitoring is recommended by the ACNS for high risk and ECMO patients. What is New: • In this cohort, neonates with sezirues were 11 times more likely of having abnromal neuroimaging findings. • Neonates with burst suppressed or suppressed EEG background were 9.5 times more likely to have abnormal neuroimaging findings. What does this study add? • This study reports a 33% incidence of neonatal seizures during ECMO. • Neonates with seizures were 11 times more likely to have an abnormal brain scan. • The study captures the real-time approach of EEG monitoring. • Recommended cEEG monitoring should last at least 24 h for ECMO patients. • This is the first study to assess this in neonates only.

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.

Continuous Amplitude-Integrated Electroencephalography During Neonatal and Pediatric Extracorporeal Membrane Oxygenation

PURPOSE

Early prognostication of neurologic outcome in neonates and children supported with extra-corporeal membrane oxygenation (ECMO) is challenging. Amplitude-integrated EEG (aEEG) offers the advantages of continuous monitoring and 24-hours availability at the bedside for intensive care unit providers. The objective of this study was to describe the early electrophysiological background patterns of neonates and children undergoing ECMO and their association with neurologic outcomes.

METHODS

This was a retrospective review of neonates and children undergoing ECMO and monitored with aEEG. Amplitude-integrated EEG was summarized as an aEEG background score determined within the first 24 hours of ECMO and divided in 3-hour periods. Screening for electrical seizures was performed throughout the full ECMO duration. Neurologic outcome was defined by the Pediatric Cerebral Performance Category score at hospital discharge.

RESULTS

Seventy-three patients (median age 79 days [8-660], median weight 4.78 kg [3.24-10.02]) were included in the analysis. Thirty-two patients had a favorable neurologic outcome and 41 had an unfavorable neurologic outcome group at hospital discharge. A 24-hour aEEG background score >17 was associated with an unfavorable outcome with a sensitivity of 44%, a specificity of 97%, a positive predictive value of 95%, and a negative predictive value of 57%. In multivariate analysis, 24-hour aEEG background score was associated with unfavorable outcome (hazard ratio, 6.1; p = 0.001; 95% confidence interval, 2.31-16.24). The presence of seizures was not associated with neurologic outcome at hospital discharge.

CONCLUSIONS

Continuous aEEG provides accurate neurologic prognostication in neonates and children supported with ECMO. Early aEEG monitoring may help intensive care unit providers to guide clinical care and family counseling.

Seizures in children undergoing extracorporeal membrane oxygenation: a systematic review and meta-analysis

OBJECTIVES

To investigate the incidence of seizures and short-term mortality associated with seizures in children undergoing extracorporeal membrane oxygenation (ECMO).

METHODS

PubMed, Embase, and Web of Science were searched from inception to September 2021. Study quality was assessed using the Newcastle-Ottawa Scale. Random effects meta-analysis was conducted.

RESULTS

Fourteen studies met the inclusion criteria for quantitative meta-analysis. The cumulative estimate of seizure incidence was 15% (95% CI: 12-17%). Studies using electroencephalography reported a higher incidence of seizures compared with those using electro-clinical criteria (19% vs. 9%, P = 0.034). Furthermore, 75% of seizures were subclinical. Children receiving extracorporeal cardiopulmonary resuscitation (ECPR) exhibited a higher incidence of seizures compared to children with respiratory and cardiac indications. Seizure incidence was higher in patients undergoing venoarterial (VA) ECMO compared with venovenous (VV) ECMO. The pooled odds ratio of mortality was 2.58 (95% CI: 2.25-2.95) in those developed seizures.

CONCLUSION

The incidence of seizures in children requiring ECMO was 15% and majority of seizures were subclinical. The incidence of seizures was higher in patients receiving ECPR than in those with respiratory and cardiac indications. Seizures were more frequent in patients undergoing VA ECMO than VV ECMO. Seizures were associated with increased short-term mortality.

IMPACT

The incidence of seizures in children undergoing extracorporeal membrane oxygenation (ECMO) was ~15% and majority of the seizures were subclinical. Seizures were associated with increased short-term mortality. Risk factors for seizures were extracorporeal cardiopulmonary resuscitation and venoarterial ECMO. Electroencephalography (EEG) monitoring is recommended in children undergoing ECMO and further studies on the optimal protocol for EEG monitoring are necessary.

Neurological monitoring in ECMO patients: current state of practice, challenges and lessons

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) in critically ill patients serves as a management option for end-stage cardiorespiratory failure in medical and surgical conditions. Patients on ECMO are at a high risk of neurologic adverse events including intracranial hemorrhage (ICH), acute ischemic stroke (AIS), seizures, diffuse cerebral edema, and hypoxic brain injury. Standard approaches to neurological monitoring for patients receiving ECMO support can be challenging for multiple reasons, including the severity of critical illness, deep sedation, and/or paralysis. This narrative literature review provides an overview of the current landscape for neurological monitoring in this population.

METHODS

A literature search using PubMed was used to aid the understanding of the landscape of published literature in the area of neurological monitoring in ECMO patients.

RESULTS

Review articles, cohort studies, case series, and individual reports were identified. A total of 73 varied manuscripts were summarized and included in this review which presents the challenges and strategies for performing neurological monitoring in this population.

CONCLUSION

Neurological monitoring in ECMO is an area of interest to many clinicians, however, the literature is limited, heterogenous, and lacks consensus on the best monitoring practices. The evidence for optimal neurological monitoring that could impact clinical decisions and functional outcomes is lacking. Additional studies are needed to identify effective measures of neurological monitoring while on ECMO.

Brain Injury in Extracorporeal Membrane Oxygenation: A Multidisciplinary Approach

Extracorporeal membrane oxygenation (ECMO) represents an established technique to provide temporary cardiac and/or pulmonary support. ECMO, in veno-venous, veno-arterial or in extracorporeal carbon dioxide removal modality, is associated with a high rate of brain injuries. These complications have been reported in 7 to 15% of adults and 20% of neonates, and are associated with poor survival. Thromboembolic events, loss of cerebral autoregulation, alteration of the blood-brain barrier, and hemorrhage related to anticoagulation represent the main causes of severe brain injury during ECMO. The most frequent forms of acute neurological injuries in ECMO patients are intracranial hemorrhage (2-21%), ischemic stroke (2-10%), seizures (2-6%), and hypoxic-ischemic brain injury; brain death may also occur in this population. Other frequent complications are infarction (1-8%) and cerebral edema (2-10%), as well as neuropsychological and psychiatric sequelae, including posttraumatic stress disorder.

Prevalence of Seizures and Risk Factors for Mortality in a Continuous Cohort of Pediatric Extracorporeal Membrane Oxygenation Patients

OBJECTIVES

To evaluate the risk factors for mortality in pediatric extracorporeal membrane oxygenation patients.

DESIGN

Retrospective, single-center study.

SETTING

PICU and Pediatric cardiothoracic ICU in an urban, quaternary care center.

PATIENTS

All neonatal and pediatric patients requiring extracorporeal membrane oxygenation at our institution between January 2014 and December 2018, who underwent a standardized continuous electroencephalogram neuromonitoring protocol during most of the duration of extracorporeal membrane oxygenation support. We excluded patients who had extracorporeal membrane oxygenation initiated at another institution.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Sixty-six children required extracorporeal membrane oxygenation support during this period. Four patients were excluded, three due to lack of electroencephalogram data, one with extracorporeal membrane oxygenation initiated at other institution. In the remaining 62, 11 patients (17%) had seizures, of which 5 (45%) had status epilepticus. Eight of 11 patients (72%) had exclusively electrographic seizures. A total of 33 patients (53.2%) died, of which 22 died during extracorporeal membrane oxygenation course, and one died 3 years after hospital discharge. Mean survival from extracorporeal membrane oxygenation initiation was 766.9 days (standard deviation, 691.7; median, 546.5; interquartile range 1-3, 97.7-1255.0). In multivariate analysis, increased risk of mortality was associated with the use of extracorporeal cardiopulmonary resuscitation (hazard ratio, 4.33; 95% CI, 1.75-10.72; p = 0.002), imaging findings of cerebral edema (hazard ratio, 14.31; 95% CI, 5.18-39.54; p < 0.001), high lactate level (> 100 mg/dL within 2 hr preextracorporeal membrane oxygenation) (hazard ratio, 1.22; 95% CI, 1.03-1.44; p = 0.022), and prolonged deep hypothermic circulatory arrest (hazard ratio, 3.43; 95% CI, 1.65-7.13; p < 0.001). Presence of seizures was associated with imaging findings of cerebral edema (hazard ratio, 4.16; 95% CI, 1.04-16.58; p = 0.04).

CONCLUSIONS

Seizures are common in children requiring extracorporeal membrane oxygenation support, with a high rate of electrographic seizures and status epilepticus, as in prior studies. Presence of cerebral edema is both risk factor for mortality and seizures. Other risk factors for mortality include extracorporeal cardiopulmonary resuscitation, high lactate levels, and prolonged deep hypothermic circulatory arrest.

Neurological Monitoring and Complications of Pediatric Extracorporeal Membrane Oxygenation Support

Extracorporeal membrane oxygenation is extracorporeal life support for life-threatening cardiopulmonary failure. Since its introduction, the use of extracorporeal membrane oxygenation has expanded to patients with more complex comorbidities without change in patient mortality rates. Although many patients survive, significant neurological complications like seizures, ischemic strokes, and intracranial hemorrhage can occur during extracorporeal membrane oxygenation care. The risks of these complications often add to the complexity of decision-making surrounding extracorporeal membrane oxygenation support. In this review, we discuss the pathophysiology and incidence of neurological complications in children supported on extracorporeal membrane oxygenation, factors influencing the incidence of these complications, commonly used neurological monitoring modalities, and outcomes for this complex patient population. We discuss the current literature on the use of electroencephalography for both seizure detection and monitoring of background electroencephalographic changes, in addition to the use of less commonly used imaging modalities like transcranial Doppler. We summarize the knowledge gaps and the lack of clinical consensus guidelines for managing these potentially life-changing neurological complications. Finally, we discuss future work to further understand the pathophysiology of extracorporeal membrane oxygenation-related neurological complications.

The Influence of Therapeutics on Prognostication After Cardiac Arrest

PURPOSE OF REVIEW

The goal of this review is to highlight the influence of therapeutic maneuvers on neuro-prognostication measures administered to comatose survivors of cardiac arrest. We focus on the effect of sedation regimens in the setting of targeted temperature management (TTM), one of the principle interventions known to improve neurological recovery after cardiac arrest. Further, we discuss the critical need for novel markers, as well as refinement of existing markers, among patients receiving extracorporeal membrane oxygenation (ECMO) in the setting of failed conventional resuscitation, known as extracorporeal cardiopulmonary resuscitation (ECPR).

RECENT FINDINGS

Automated pupillometry may have some advantage over standard pupillary examination for prognostication following TTM, sedation, or the use of ECMO after cardiac arrest. New serum biomarkers such as Neurofilament light chain have shown good predictive abilities and need further validation in these populations. There is a high-level uncertainty in brain death declaration protocols particularly related to apnea testing and appropriate ancillary tests in patients receiving ECMO. Both sedation and TTM alone and in combination have been shown to affect prognostic markers to varying degrees. The optimal approach to analog-sedation is unknown, and requires further study. Moreover, validation of known prognostic markers, as well as brain death declaration processes in patients receiving ECMO is warranted. Data on the effects of TTM, sedation, and ECMO on biomarkers (e.g., neuron-specific enolase) and electrophysiology measures (e.g., somatosensory-evoked potentials) is sparse. The best approach may be one customized to the individual patient, a precision-medicine approach.

Early Electroencephalography Findings in Cardiogenic Shock Patients Treated by Venoarterial Extracorporeal Membrane Oxygenation

OBJECTIVES

We aimed to assess early electroencephalography findings in patients treated by venoarterial extracorporeal membrane oxygenation and their association with neurologic outcome.

DESIGN

Single-center observational study.

SETTING

Medical ICU of a university hospital.

PATIENTS

An early standardized electroencephalography assessment, that is, standard electroencephalography followed by continuous electroencephalography, was performed in consecutive cardiogenic shock patients requiring venoarterial extracorporeal membrane oxygenation. Associations between electroencephalography findings and outcome, defined as a composite of acute brain injury or death at 14 days, were investigated.

MEASUREMENTS AND MAIN RESULTS

Twenty-two patients with a median Full Outline of Unresponsiveness score of 4 (interquartile range, 3-6) were studied. Pupillary light reflex, corneal reflex, and cough reflex were preserved in 20 (90%), 17 (77%), and 17 (77%) patients, respectively. Overall, standard electroencephalography findings consisted of diffuse slowing in 21 patients (95%) and severe background abnormalities in 13 patients (59%) (i.e., a discontinuous [n = 5; 23%] and/or an unreactive background [n = 9; 41%]). Severe background abnormalities on standard electroencephalography (poor outcome rate: 69% vs 22%; p = 0.03) and absence of sleep transients on continuous electroencephalography (poor outcome rate: 67% vs 14%; p = 0.02) were associated with a poor outcome, whereas neurologic findings and doses of sedation were not. Patients without sleep transients on continuous electroencephalography tended to have lower Full Outline of Unresponsiveness scores than patients with preserved sleep transients-appearing patterns.

CONCLUSIONS

In patients treated by venoarterial extracorporeal membrane oxygenation, early severe background abnormalities on standard electroencephalography provide important information on neurologic outcome. The lack of sleep transients on continuous electroencephalography reflects the severity of brain dysfunction and might represent an additional prognostic marker.

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

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

Neuromonitoring in the neonatal ECMO patient

Utilization of extraocorporeal membrane oxygenation (ECMO) has become increasingly widespread as a bridging therapy for neonates with severe, reversible respiratory or cardiac diseases. While significant risks remain, due to advances in medical and surgical management, overall mortality has decreased. However, short and long-term neurological morbidity has remained high. Therefore, increasing attention has been focused on multimodal neuromonitoring to track and optimally, minimize or prevent intracranial injury. This review will explore the the indications, advantages, disadvantages, timing, frequency, duration, and any known correlation with neurodevelopmental outcomes of common types of neuromonitoring in the neonatal ECMO population. Investigational monitoring techniques such as NIRS will be briefly reviewed.

Electrographic Seizures in Children and Neonates Undergoing Extracorporeal Membrane Oxygenation

OBJECTIVE

We aimed to determine the prevalence and risk factors for electrographic seizures in neonates and children requiring extracorporeal membrane oxygenation support.

DESIGN

Prospective quality improvement project.

SETTING

Quaternary care pediatric institution.

PATIENTS

Consistent with American Clinical Neurophysiology Society electroencephalographic monitoring recommendations, neonates and children requiring extracorporeal membrane oxygenation support underwent clinically indicated electroencephalographic monitoring.

INTERVENTIONS

We performed a 2-year quality improvement study from July 2013 to June 2015 evaluating electrographic seizure prevalence and risk factors.

MAIN RESULTS

Ninety-nine of 112 patients (88%) requiring extracorporeal membrane oxygenation support underwent electroencephalographic monitoring. Electrographic seizures occurred in 18 patients (18%), of whom 11 patients (61%) had electrographic status epilepticus and 15 patients (83%) had exclusively electrographic-only seizures. Electrographic seizures were more common in patients with low cardiac output syndrome (p = 0.03). Patients with electrographic seizures were more likely to die prior to discharge (72% vs 30%; p = 0.01) and have unfavorable outcomes (54% vs 17%; p = 0.004) than those without electrographic seizures.

CONCLUSIONS

Electrographic seizures occurred in 18% of neonates and children requiring extracorporeal membrane oxygenation support, often constituted electrographic status epilepticus, and were often electrographic-only thereby requiring electroencephalographic monitoring for identification. Low cardiac output syndrome was associated with an increased risk for electrographic seizures. Electrographic seizures were associated with higher mortality and unfavorable outcomes. Further investigation is needed to determine whether electrographic seizures identification and management improves outcomes.

Extracorporeal membrane oxygenation: a breakthrough for respiratory failure

Extracorporeal membrane oxygenation (ECMO) is a method for providing long-term treatment of a patient in a modified heart-lung machine. Desaturated blood is drained from the patient, oxygenated and pumped back to a major vein or artery. ECMO supports heart and lung function and may be used in severe heart and/or lung failure when conventional intensive care fails. The Stockholm programme started in 1987 with treatment of neonates. In 1995, the first adult patient was accepted onto the programme. Interhospital transportation during ECMO was started in 1996, which enabled retrieval of extremely unstable patients during ECMO. Today, the programme has an annual volume of about 80 patients. It has been characterized by, amongst other things, minimal patient sedation. By 31 December 2014, over 900 patients had been treated, the vast majority for respiratory failure, and over 650 patients had been transported during ECMO. The median ECMO duration was 5.3, 5.7 and 7.1 days for neonatal, paediatric and adult patients, respectively. The survival to hospital discharge rate for respiratory ECMO was 81%, 70% and 63% in the different age groups, respectively, which is significantly higher than the overall international experience as reported to the Extracorporeal Life Support Organization (ELSO) Registry (74%, 57% and 57%, respectively). The survival rate was significantly higher in the Stockholm programme compared to ELSO for meconium aspiration syndrome, congenital diaphragmatic hernia in neonates and pneumocystis pneumonia in paediatric patients.

Subclinical seizures identified by postoperative electroencephalographic monitoring are common after neonatal cardiac surgery

OBJECTIVES

The American Clinical Neurophysiology Society recommends continuous electroencephalographic monitoring after neonatal cardiac surgery because seizures are common, often subclinical, and associated with worse neurocognitive outcomes. We performed a quality improvement project to monitor for postoperative seizures in neonates with congenital heart disease after surgery with cardiopulmonary bypass.

METHODS

We implemented routine continuous electroencephalographic monitoring and reviewed the results for an 18-month period. Clinical data were collected by chart review, and continuous electroencephalographic tracings were interpreted using standardized American Clinical Neurophysiology Society terminology. Electrographic seizures were classified as electroencephalogram-only or electroclinical seizures. Multiple logistic regression was used to assess associations between seizures and potential clinical and electroencephalogram predictors.

RESULTS

A total of 161 of 172 eligible neonates (94%) underwent continuous electroencephalographic monitoring. Electrographic seizures occurred in 13 neonates (8%) beginning at a median of 20 hours after return to the intensive care unit after surgery. Neonates with all types of congenital heart disease had seizures. Seizures were electroencephalogram only in 11 neonates (85%). Status epilepticus occurred in 8 neonates (62%). In separate multivariate models, delayed sternal closure or longer deep hypothermic circulatory arrest duration was associated with an increased risk for seizures. Mortality was higher among neonates with than without seizures (38% vs 3%, P < .001).

CONCLUSIONS

Continuous electroencephalographic monitoring identified seizures in 8% of neonates after cardiac surgery with cardiopulmonary bypass. The majority of seizures had no clinical correlate and would not have been otherwise identified. Seizure occurrence is a marker of greater illness severity and increased mortality. Further study is needed to determine whether seizure identification and management lead to improved outcomes.

Electrographic seizures and status epilepticus in critically ill children and neonates with encephalopathy

Electrographic seizures are seizures that are evident on EEG monitoring. They are common in critically ill children and neonates with acute encephalopathy. Most electrographic seizures have no associated clinical changes, and continuous EEG monitoring is necessary for identification. The effect of electrographic seizures on outcome is the focus of active investigation. Studies have shown that a high burden of electrographic seizures is associated with worsened clinical outcome after adjustment for cause and severity of brain injury, suggesting that a high burden of such seizures might independently contribute to secondary brain injury. Further research is needed to determine whether identification and management of electrographic seizures reduces secondary brain injury and improves outcome in critically ill children and neonates.

A review of long-term EEG monitoring in critically ill children with hypoxic-ischemic encephalopathy, congenital heart disease, ECMO, and stroke

Continuous EEG monitoring is being used with increasing frequency in critically ill children with hypoxic ischemic encephalopathy, congenital heart disease, stroke, and extracorporeal membrane oxygenation (ECMO). The primary indication for EEG monitoring is to identify electrographic seizures and electrographic status epilepticus, which have been associated with worse outcome in some populations. A secondary indication is to provide prognostic information. This review summarizes the available data regarding continuous EEG monitoring in critically ill children with special attention to hypoxic ischemic encephalopathy, congenital heart disease, stroke, and children undergoing ECMO.

Nonconvulsive seizures are common in children treated with extracorporeal cardiac life support

OBJECTIVES

The prevalence of electrographic seizures or nonconvulsive status epilepticus and the effect of such seizures in children treated with extracorporeal cardiac life support are not known. We investigated the occurrence of electrographic abnormalities, including asymmetries in amplitude or frequency of the background rhythm and interictal activity in children undergoing extracorporeal cardiac life support and their association with seizures. We compared mortality and radiologic evidence of neurologic injury between patients with seizures and those without seizures.

DESIGN

Retrospective review of medical records and the Extracorporeal Life Support Organization database.

SETTING

PICU at a single institution.

PATIENTS

All pediatric patients up to 18 years old, who had extracorporeal cardiac life support and continuous electroencephalography monitoring between the years 2006 and 2011.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Nineteen patients treated with extracorporeal cardiac life support underwent continuous electroencephalography monitoring. Seizures occurred in four patients (21%) and were exclusively nonconvulsive in three patients. Two of these four patients had nonconvulsive status epilepticus. Interictal discharges on electroencephalography were associated with seizures (odds ratio, 19.5 [95% CI, 1.29-292.75]; p = 0.03). Only 50% of the seizures were detected in the first hour of monitoring, whereas all seizures were detected within 24 hours. All patients with seizures had structural abnormalities seen on neuroimaging. Seizures were not significantly associated with increased mortality. To evaluate for ascertainment bias, we compared outcomes between patients who underwent extracorporeal cardiac life support and received continuous electroencephalography monitoring and those patients who underwent extracorporeal cardiac life support during the study period but did not receive electroencephalography (n = 30).

CONCLUSIONS

Seizures are common in children during extracorporeal cardiac life support, and most seizures are nonconvulsive. In patients undergoing extracorporeal cardiac life support, clinical features are unreliable indicators of the presence of seizures. The presence of seizures is suggestive of CNS injury. This study is limited by the exclusion of neonates, a feature of the clinical use of electroencephalography at our institution. Although seizures were not associated with increased mortality, further prospective studies in larger populations are needed to assess the long-term morbidity associated with seizures during extracorporeal cardiac life support.

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.

When combined, early bedside head ultrasound and electroencephalography predict abnormal computerized tomography or magnetic resonance brain images obtained after extracorporeal membrane oxygenation treatment

Definitive neuroimaging of the brain using computerized tomography (CT) or magnetic resonance imaging (MRI) in extracorporeal membrane oxygenation (ECMO)-treated infants must be delayed until after this therapy is completed. Bedside head ultrasound (HUS) and electroencephalography (EEG) studies during ECMO, if highly correlated with later definitive neuroimaging, might be used to affect the acute clinical care and early parental counseling of infants with severe cardiorespiratory failure. One hundred and sixty ECMO-treated patients had both bedside EEG and HUS studies performed during ECMO, as well as a later CT or MRI study prior to hospital discharge. There was a significant difference in CT or MRI findings among patients having normal studies on both the HUS and EEG, compared to those having an abnormality on either the HUS or the EEG, and compared to those having abnormalities on both studies. In ECMO-treated infants, the combination of a normal bedside HUS and an EEG without marked abnormalities is highly predictive of normal post-ECMO CT and MRI neuroimaging studies.

Neonatal electroencephalogram does not predict cognitive and academic achievement scores at early school age in survivors of neonatal extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation is an effective rescue treatment for severe cardiorespiratory failure in term or near-term neonates, although a wide range of neurologic sequelae have been noted in a substantial minority of survivors. The objective of the present study was to determine the value of the neonatal electroencephalogram (EEG) for predicting Wechler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), Wide Range Achievement Test, and Wide Range Assessment of Memory and Language scores at early school age in 66 testable survivors of extracorporeal membrane oxygenation who were not severely brain damaged. Technically satisfactory EEG recordings were obtained at least twice following admission to our nursery and prior to discharge. The EEGs were classified and graded according to standard criteria. The developmental test results of those who had only normal or mildly abnormal neonatal EEGs (group 1, n = 9) were compared with those who had at least one moderately or markedly abnormal recording (group 2, n = 57). School-age test and subtest scores were not statistically significantly worse in group 2 versus group 1 infants. No child in group 1 and five children in group 2 had WPPSI-R Full-Scale IQ scores of less than 70. Of the nine children in group 2 who had at least one markedly abnormal neonatal EEG recording (graded as burst suppression or as electrographic seizure), only two had abnormally low WPPSI-R Full-Scale IQ scores. We conclude that EEG recordings obtained during the neonatal course of neonates treated with extracorporeal membrane oxygenation do not predict cognitive and academic achievement test results in survivors at early school age who were testable and not severely brain damaged.

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.

Clinical antecedents of neurologic and audiologic abnormalities in survivors of neonatal extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation is an effective rescue treatment for severe cardiorespiratory failure in term or near term neonates, although cerebral palsy, mental retardation, and sensorineural hearing loss are observed in 10 to 20% of survivors. The objective of the present study was to identify potential risk factors that may explain the neurologic and audiologic sequelae noted in 19% of 181 survivors of neonatal extracorporeal membrane oxygenation from our hospital. Our results suggest the following findings in survivors of severe cardiorespiratory failure treated with neonatal extracorporeal membrane oxygenation: (1) hypotension or the need for cardiopulmonary resuscitation before extracorporeal membrane oxygenation significantly increases the risk of spastic cerebral palsy, (2) profound hypocarbia before extracorporeal membrane oxygenation is associated with a significantly increased risk of hearing loss, (3) mental retardation in the absence of spastic cerebral palsy is unexplained except when due to abnormal fetal brain development, and (4) hypoxemia in the absence of hypotension does not increase the risk of neurologic or audiologic sequelae.

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.

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.

Complications of neonatal extracorporeal membrane oxygenation

From 1973-1985 to 1988 the average patient complications per case were 1.44 per case and significantly increased during 1990 to 1992 to 2.10 per case (Figure 3). During the same periods patient survival significantly decreased from 84% (1973-1985 to 1988, n = 2463) to 80% (1990 to 1992, n = 4005) (Figure 4). The association between total complication rates and survival rate was examined by regression analysis (Table 5). The correlation of patient complication rate and total complication rate with survival is highly significant; however, causality cannot be established. When comparing different entry criteria (Table 2) for incidence of mechanical and patient complications, no significant differences are apparent. This is not surprising since each of the entry criteria were designed to identify the same patient population. When premature neonates (> 35 weeks) were placed on ECMO, 36% of them had intracranial haemorrhage (ICH) with 62% mortality while only 12% of the neonates < 35 weeks had ICH and a 49% mortality. Similar findings were noted with low birthweight neonates (< 2.2 kg), 28% had ICH with 64% mortality while only 12% of the neonates > 2.2 kg had ICH with a 50% mortality. Selection criteria remain problematic for a variety of reasons. They cannot be viewed as absolute because of variability between centres. What represents likely 80% mortality in one centre may not apply to another. Historical controls are misleading because changing respiratory therapy strategies make historical populations difficult to compare. Also, once an ECMO centre becomes established, a more challenging group of patients will be attracted than previously was the case. Further, a single entry criterion cannot be generalized for all entry diagnoses. Criteria for an 80% predicted mortality is probably not the same for MAS, CHN, PPHN, and sepsis. Subsequent patients registered in the Neonatal ECMO Registry of the Extracorporeal Life Support Organization will address these issues more thoroughly, as specific details of the pre-ECMO condition and therapeutic strategies are collected. This collective review should help to identify trends which require reassessment of technique or patient management.

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.

Cerebrovascular lesions in infants and children dying after extracorporeal membrane oxygenation

The neuropathologic autopsy findings of a group of infants and children at Children's Hospital of Pittsburgh who died after treatment with extracorporeal membrane oxygenation (ECMO) were reviewed and tabulated. The study surveyed an 11-year period (February, 1980 to May, 1991); of 268 children receiving ECMO therapy for severe cardiopulmonary failure, 94 patients died, 70 of whom were autopsied and permission for brain examination was granted in only 44. The frequency of ischemic neuronal necrosis (50%), focal cerebral infarcts (50%), intracerebral hemorrhages (52%), and periventricular leukomalacia (41%) was higher in this group of ECMO-treated patients than that observed in the general autopsy population from which the study patients were selected. The frequency of ischemic and hemorrhagic brain lesions was similar among neonates and older infants and children. This documentation of cerebrovascular lesions in children dying after ECMO may provide a better understanding of potential brain damage in the larger population of infants and children who survive this invasive procedure.