Cause and Prevention of Central Nervous System Injury in Neonates Undergoing Cardiac Surgery

Evaluation of end-organ protection in newborns and infants after surgery of aortic arch hypoplasia: A prospective randomized study

IntroductionSurgical repair of aortic arch hypoplasia in children requires a "dry" surgical field with reliable end-organ protection. Perfusion strategies commonly involve deep hypothermic circulatory arrest (DHCA) and variations of the continuous perfusion techniques, such as selective antegrade cerebral perfusion (SACP) and full-flow perfusion with double aortic cannulation (DAC). We aimed to evaluate the end-organ protection in the surgery of aortic arch hypoplasia in newborns and infants using DHCA and DAC.Materials and methods66 newborns and infants with aortic arch hypoplasia and biventricular anatomy were enrolled in this prospective study. Patients were randomly assigned into two groups according to the perfusion strategy - DHCA (n = 33); and DAC (n = 33). Primary endpoint: acute kidney injury (AKI), graded according to the KDIGO score. Secondary endpoints: neurological sequelae (pre- and postoperative MRI), in-hospital mortality.ResultsThe lowest temperature was 32 (28; 34)°С in the DAC group and 23 (20; 25)°С in the DHCA group. The patients with DAC had lower incidence of AKI (6 patients (18.2%) versus 19 patients (57.6%); p = .017). In the multivariate analysis, the inotropic index at 48 h was identified as a risk factor, increasing the risk of AKI by 4%. The DHCA group was associated with a 3.8-fold increase in the risk of AKI. There was no difference in hospital mortality between the DAC and DHCA groups (1 patient (3%) versus 3 patients (9.1%); p = .61). Neurological sequelae by MRI scan were observed in 18 patients (54.5%) in the DHCA group compared to 5 patients (15.15%) in the DAC group (p = .026). The only risk factor identified in the multivariate analysis for neurological lesions on MRI scan was the DHCA group, which increased the risk by 8.8 times.ConclusionsSurgical reconstruction of the aortic arch hypoplasia using the method of full-body perfusion reduces the incidence of neurological lesions and renal complications requiring renal replacement therapy compared with the deep hypothermic circulatory arrest in neonates and infants.

Cerebral Autoregulation Status in Relation to Brain Injury on Electroencephalogram and Magnetic Resonance Imaging in Children Following Cardiac Surgery

Background Disturbed cerebral autoregulation has been reported in children with congenital heart disease before and during cardiopulmonary bypass surgery, but not after. We sought to characterize the cerebral autoregulation status in the early postoperative period in relation to perioperative variables and brain injuries. Methods and Results A prospective and observational study was conducted in 80 patients in the first 48 hours following cardiac surgery. Cerebral oximetry/pressure index (COPI) was retrospectively calculated as a moving linear correlation coefficient between mean arterial blood pressure and cerebral oxygen saturation. Disturbed autoregulation was defined as COPI >0.3. Correlations of COPI with demographic and perioperative variables as well as brain injuries on electroencephalogram and magnetic resonance imaging and early outcomes were analyzed. Thirty-six (45%) patients had periods of abnormal COPI for 7.81 hours (3.38 hours) either at hypotension (median <45 mm Hg) or hypertension (median >90 mm Hg) or both. Overall, COPI became significantly lower over time, suggesting improved autoregulatory status during the 48 postoperative hours. All of the demographic and perioperative variables were significantly associated with COPI, which in turn was associated with the degree of brain injuries and early outcomes. Conclusions Children with congenital heart disease following cardiac surgery often have disturbed autoregulation. Cerebral autoregulation is at least partly the underlying mechanism of brain injury in those children. Careful clinical management to manipulate the related and modifiable factors, particularly arterial blood pressure, may help to maintain adequate cerebral perfusion and reduce brain injury early after cardiopulmonary bypass surgery. Further studies are warranted to determine the significance of impaired cerebral autoregulation in relation to long-term neurodevelopment outcomes.

Risk Factors of Perioperative Brain Injury in Children Under Two Years Undergoing Coarctation Repair

BACKGROUND

To investigate clinical manifestations and factors of perioperative brain injury (PBI) after surgical repair of coarctation of the aorta (CoA) combined with other heart malformations under cardiopulmonary bypass (CPB) in children under two years.

METHODS

The clinical data of 100 children undergoing CoA repair were retrospectively reviewed between January 2010 and September 2021. Univariate and multivariate analyses were performed to identify factors of PBI development. Hierarchical and K-means cluster analyses were conducted to evaluate the association between hemodynamic instability and PBI.

RESULTS

Eight children developed postoperative complications, and all of them had a favorable neurological outcome one year after surgery. Univariate analysis revealed eight risk factors associated with PBI. Multivariate analysis indicated operation duration (P = 0.04, odds ratio [OR], 2.93; 95% confidence interval [CI], 1.04 to 8.28) and pulse pressure (PP) minimum (P = 0.01; OR, 0.22; 95% CI, 0.06 to 0.76) were independently associated with PBI. The following three parameters emerged for cluster analysis: PP minimum, mean arterial pressure (MAP) dispersion, and systemic vascular resistance (SVR) average. Using cluster analysis, PBI mainly occurred in subgroups 1 (12%, three of 26) and 2 (10%, five of 48). The mean value of PP and MAP in subgroup 1 was significantly higher than in subgroup 2. The mean SVR in subgroup 1 was the highest. The lowest PP minimum, MAP, and SVR were observed in subgroup 2.

CONCLUSION

Lower PP minimum and longer operation duration were independent risk factors for developing PBI in children under two years during CoA repair. Unstable hemodynamics should be avoided during CPB.

[Correlation between optic nerve sheath diameter and extracorporeal life support time]

INTRODUCTION

The objective of the study was to analyse the correlation between extracorporeal life support (ECLS) and aortic cross-clamp times and optic nerve sheath diameter (ONSD).

PATIENTS AND METHODS

Study in a cohort of patients aged 0 to 15 years that underwent ECLS for cardiac surgery after obtention of signed informed consent. We calculated a sample size of 23 participants. First, we obtained 3 vertical and 3 horizontal measurements of the ONSD for each eye and calculated the mean of both eyes for each measurement to be used in the analysis. The measurements were made at admission and at 6 and 24hours post surgery. We retrieved the ECLS time and the aortic cross-clamp time were from the operative report.

RESULTS

We analysed data for 23 participants, 52.2% female, with a median age of 14 months. The median ECLS time was 60minutes; the median aortic cross-clamp time was 32minutes. The median baseline ONSD was 3.1mm. ONSD values had increased a median of 0.015mm at 6hours post surgery (P=.03). We found a positive correlation between ECLS time and ONSD values (r=0.476, p<,05). The ONSD values returned to baseline by 24hours post surgery. None of the patients developed signs or symptoms of increased intracranial pressure.

CONCLUSION

Our study found a correlation between ECLS time and ONSD at 24hours post surgery. We found variations in the ONSD even in patients without signs or symptoms of increased increased intracranial pressure. Further research is required to identify the factors related to these variations.

Early morbidities following paediatric cardiac surgery: a mixed-methods study

Background

Over 5000 paediatric cardiac surgeries are performed in the UK each year and early survival has improved to > 98%.

Objectives

We aimed to identify the surgical morbidities that present the greatest burden for patients and health services and to develop and pilot routine monitoring and feedback.

Design and setting

Our multidisciplinary mixed-methods study took place over 52 months across five UK paediatric cardiac surgery centres.

Participants

The participants were children aged < 17 years.

Methods

We reviewed existing literature, ran three focus groups and undertook a family online discussion forum moderated by the Children’s Heart Federation. A multidisciplinary group, with patient and carer involvement, then ranked and selected nine key morbidities informed by clinical views on definitions and feasibility of routine monitoring. We validated a new, nurse-administered early warning tool for assessing preoperative and postoperative child development, called the brief developmental assessment, by testing this among 1200 children. We measured morbidity incidence in 3090 consecutive surgical admissions over 21 months and explored risk factors for morbidity. We measured the impact of morbidities on quality of life, clinical burden and costs to the NHS and families over 6 months in 666 children, 340 (51%) of whom had at least one morbidity. We developed and piloted methods suitable for routine monitoring of morbidity by centres and co-developed new patient information about morbidities with parents and user groups.

Results

Families and clinicians prioritised overlapping but also different morbidities, leading to a final list of acute neurological event, unplanned reoperation, feeding problems, renal replacement therapy, major adverse events, extracorporeal life support, necrotising enterocolitis, surgical infection and prolonged pleural effusion. The brief developmental assessment was valid in children aged between 4 months and 5 years, but not in the youngest babies or 5- to 17-year-olds. A total of 2415 (78.2%) procedures had no measured morbidity. There was a higher risk of morbidity in neonates, complex congenital heart disease, increased preoperative severity of illness and with prolonged bypass. Patients with any morbidity had a 6-month survival of 81.5% compared with 99.1% with no morbidity. Patients with any morbidity scored 5.2 points lower on their total quality of life score at 6 weeks, but this difference had narrowed by 6 months. Morbidity led to fewer days at home by 6 months and higher costs. Extracorporeal life support patients had the lowest days at home (median: 43 days out of 183 days) and highest costs (£71,051 higher than no morbidity).

Limitations

Monitoring of morbidity is more complex than mortality, and hence this requires resources and clinician buy-in.

Conclusions

Evaluation of postoperative morbidity provides important information over and above 30-day survival and should become the focus of audit and quality improvement.

Future work

National audit of morbidities has been initiated. Further research is needed to understand the implications of feeding problems and renal failure and to evaluate the brief developmental assessment.

Funding

This project was funded by the NIHR Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 30. See the NIHR Journals Library website for further project information.

Part II. Comparison of Neurodevelopmental Outcomes Between Normothermic and Hypothermic Pediatric Cardiopulmonary Bypass

Objectives: In the previous study we demonstrated that normothermic cardiopulmonary bypass (N-CPB, ≥35°C) provided better early clinical outcomes compared to mild/moderate hypothermic cardiopulmonary bypass (H-CPB, 28-34°C) for congenital heart surgery. In this follow-up study we compare early neurodevelopmental outcomes 2-3 years post-surgery. Methods: In this retrospective, non-randomized observational study, the medical notes of children from our previous cohort were reviewed after 2-3 years. Demographic and neurodevelopmental outcomes were tabulated to enable blinded statistical analysis comparing outcomes between N-CPB and H-CPB surgery for congenital heart defects. Multivariate logistic regression models were developed to identify any differences in outcomes after adjustment for confounders. Results: Ninety-five children who underwent H-CPB (n = 50) or N-CPB (n = 45) were included. The proportions of patients with one or more adverse neurodevelopmental outcomes 2-3 years later were 14/50 (28.0%) in the H-CPB group and 11/45 (24.4%) in N-CPB, which was not significantly different between groups (p = 0.47). The two CPB groups were balanced for demographic and surgical risk factors, with the exception of genetic conditions. A higher incidence of H-CPB patients acquired learning difficulties [23.1% compared to 2.56% for N-CPB (p = 0.014)] and neurological deficits [30.8% compared to 7.69% for N-CPB (p = 0.019)], but these differences were not robust to adjustment for genetic syndromes. Conclusions: Our study did not reveal any significant differences in early neurodevelopmental outcomes between H-CPB or N-CPB surgery for congenital heart defects. The most important factor in predicting outcomes was, as expected, the presence of a genetic syndrome. We found no evidence that CPB temperature affects early neurodevelopmental outcomes.

Bedside clinical neurologic assessment utilisation in paediatric cardiac intensive care units

IntroductionNeurodevelopmental disabilities in children with CHD can result from neurologic injury sustained in the cardiac ICU when children are at high risk of acute neurologic injury. Physicians typically order and specify frequency for serial bedside nursing clinical neurologic assessments to evaluate patients' neurologic status.Materials and methodsWe surveyed cardiac ICU physicians to understand how these assessments are performed, and the attitudes of physicians on the utility of these assessments. The survey contained questions regarding assessment elements, assessment frequency, communication of neurologic status changes, and optimisation of assessments. RESULTS: Surveys were received from 50 institutions, with a response rate of 86%. Routine clinical neurologic assessments were reported to be performed in 94% of institutions and standardised in 56%. Pupillary reflex was the most commonly reported assessment. In all, 77% of institutions used a coma scale, with Glasgow Coma Scale being most common. For patients with acute brain injury, 82% of institutions reported performing assessments hourly, whereas assessment frequency was more variable for low-risk and high-risk patients without overt brain injury. In all, 84% of respondents thought their current practice for assessing and monitoring neurologic status was suboptimal. Only 41% felt that the Glasgow Coma Scale was a valuable tool for assessing neurologic function in the cardiac ICU, and 91% felt that a standardised approach to assessing pre-illness neurologic function would be valuable. CONCLUSIONS: Routine nursing neurologic assessments are conducted in most surveyed paediatric cardiac ICUs, although assessment characteristics vary greatly between institutions. Most clinicians rated current neurologic assessment practices as suboptimal.

Long-term early development research in congenital heart disease (LEADER-CHD): a study protocol for a prospective cohort observational study investigating the development of children after surgical correction for congenital heart defects during the first 3 years of life

INTRODUCTION

Congenital heart disease (CHD) is the most common birth defect. Studies on the development of children with CHD point towards deficits in motoric, cognitive and language development. However, most studies are cross-sectional and there is a gap in the knowledge concerning developmental trajectories, risk and protective factors and a lack of research concerning environmental predictors. Specifically, no studies have so far considered the importance of early caregiving experiences and child temperament for the development of children with CHD.

METHODS

In a single-centre prospective cohort study, cognitive, motoric and language development of 180 children after corrective surgery for a simple transposition of the great arteries (TGA), tetralogy of Fallot (TOF) or ventricular septal defect (VSD) will be assessed at ages 12, 24 and 36 months with the Bayley Scales of Infant Development 3rd Edition (BSID-III). At age 12 months, a free-play video observation will be conducted to investigate the relationship between primary caregiver and child, and child temperament will be assessed with the Infant Behavior Questionnaire-Revised Short Version. Medical information will be obtained from patient records and demographic information via questionnaires.

ANALYSIS

Frequency and severity of developmental delays will be reported descriptively. Differences between groups (TGA, TOF, VSD) will be subjected to repeated-measures analysis across time points. Multiple regressions will be applied for the analysis of predictors at each time point. For the analysis of differential developmental trajectories, mixed-model analysis will be applied.

ETHICS AND DISSEMINATION

The study has been approved by the local medical ethics committee. Written informed consent will be obtained from all participants. Parents have the option to be debriefed about BSID-III results after each assessment and about the study results after project completion. Results will be disseminated in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

DRKS00011006; Pre-results.

Neuroprotective Anesthesia Regimen and Intensive Management for Pediatric Cardiac Surgery with Cardiopulmonary Bypass: a Review and Initial Experience

This article describes our proposal for routine anesthesia, intraoperative medical management, cerebral and physiological monitoring during pediatric cardiac surgery with cardiopulmonary bypass that intend to provide appropriate anesthesia (analgesia, hypnosis), neuroprotection, adequate cerebral and systemic oxygen supply, and preventing against drugs neurotoxicity. A concise retrospective data is presented.

Validity of the Montreal Cognitive Assessment Screener in Adolescents and Young Adults With and Without Congenital Heart Disease

BACKGROUND

Cognitive deficits are common, long-term sequelae in children and adolescents with congenital heart disease (CHD) who have undergone surgical palliation. However, there is a lack of a validated brief cognitive screening tool appropriate for the outpatient setting for adolescents with CHD. One candidate instrument is the Montreal Cognitive Assessment (MoCA) questionnaire.

OBJECTIVE

The purpose of the research was to validate scores from the MoCA against the General Memory Index (GMI) of the Wide Range Assessment of Memory and Learning, 2nd Edition (WRAML2), a widely accepted measure of cognition/memory, in adolescents and young adults with CHD.

METHODS

We administered the MoCA and the WRAML2 to 156 adolescents and young adults ages 14-21 (80 youth with CHD and 76 healthy controls who were gender and age matched). Spearman's rank order correlations were used to assess concurrent validity. To assess construct validity, the Mann-Whitney U test was used to compare differences in scores in youth with CHD and the healthy control group. Receiver operating characteristic curves were created and area under the curve, sensitivity, specificity, positive predictive value, and negative predictive value were also calculated.

RESULTS

The MoCA median scores in the CHD versus healthy controls were (23, range 15-29 vs. 28, range 22-30; p < .001), respectively. With the screening cutoff scores at <26 points for the MoCA and 85 for GMI (<1 SD, M = 100, SD = 15), the CHD versus healthy control groups showed sensitivity of .96 and specificity of .67 versus sensitivity of .75 and specificity of .90, respectively, in the detection of cognitive deficits. A cutoff score of 26 on the MoCA was optimal in the CHD group; a cutoff of 25 had similar properties except for a lower negative predictive value. The area under the receiver operating characteristic curve (95% CI) for the MoCA was 0.84 (95% CI [0.75, 0.93], p < .001) and 0.84 (95% CI [0.62, 1.00], p = .02) for the CHD and controls, respectively.

DISCUSSION

Scores on the MoCA were valid for screening to detect cognitive deficits in adolescents and young adults aged 14-21 with CHD when a cutoff score of 26 is used to differentiate youth with and without significant cognitive impairment. Future studies are needed in other adolescent disease groups with known cognitive deficits and healthy populations to explore the generalizability of validity of MoCA scores in adolescents and young adults.

Definition of important early morbidities related to paediatric cardiac surgery

BACKGROUND

Morbidity is defined as a state of being unhealthy or of experiencing an aspect of health that is "generally bad for you", and postoperative morbidity linked to paediatric cardiac surgery encompasses a range of conditions that may impact the patient and are potential targets for quality assurance.

METHODS

As part of a wider study, a multi-disciplinary group of professionals aimed to define a list of morbidities linked to paediatric cardiac surgery that was prioritised by a panel reflecting the views of both professionals from a range of disciplines and settings as well as parents and patients.

RESULTS

We present a set of definitions of morbidity for use in routine audit after paediatric cardiac surgery. These morbidities are ranked in priority order as acute neurological event, unplanned re-operation, feeding problems, the need for renal support, major adverse cardiac events or never events, extracorporeal life support, necrotising enterocolitis, surgical site of blood stream infection, and prolonged pleural effusion or chylothorax. It is recognised that more than one such morbidity may arise in the same patient and these are referred to as multiple morbidities, except in the case of extracorporeal life support, which is a stand-alone constellation of morbidity.

CONCLUSIONS

It is feasible to define a range of paediatric cardiac surgical morbidities for use in routine audit that reflects the priorities of both professionals and parents. The impact of these morbidities on the patient and family will be explored prospectively as part of a wider ongoing, multi-centre study.

Neurological Complications of Cardiac Disease

This article focuses on the complex interactions between the cardiovascular and neurologic systems. Initially, we focus on neurological complications in children with congenital heart disease both secondary to the underlying cardiac disease and complications of interventions. We later discuss diagnosis and management of common syncope syndromes with emphasis on vasovagal syncope. We also review the diagnosis, classification, and management of children and adolescents with postural orthostatic tachycardia syndrome. Lastly, we discuss long QT syndrome and sudden unexpected death in epilepsy (SUDEP), reviewing advances in genetics and current knowledge of pathophysiology of these conditions. This article attempts to provide an overview of these disorders with focus on pathophysiology, advances in molecular genetics, and current medical interventions.

Improving Neurodevelopmental Surveillance and Follow-up in Infants with Congenital Heart Disease

OBJECTIVE

We hypothesize that neurodevelopmental surveillance of targeted patients with congenital heart disease during the admission for their cardiac surgery would improve neurodevelopmental assessment and outpatient follow-up rates.

DESIGN

All patients under 12 months of age who were operated on between October 2013 and October 2014 and were considered at risk for neurodevelopmental delay in accordance with the 2012 American Heart Association Scientific Statement were included. A protocol was implemented to increase surveillance of targeted patients during the hospitalization for their cardiac surgery. A historical control cohort was used from a 6-month period that preceded initiation of the program from July 2012 to December 2012. Univariate analysis assessed the effects of patient demographics, anatomy, postoperative course, and distance from clinic on inpatient screening and follow-up to evaluate areas for future improvement.

RESULTS

Neurodevelopmental surveillance in the post-protocol period increased from 21% to 82% (P < .001) as did compliance rates for outpatient follow-up from 38% to 52% (P < .001). Patients receiving consultation were younger (median 1.2 months range 0.3-3.1 vs. 4.0 range 1.2-5.5, P = .002), had a longer intensive care unit duration (median 8 days range 4-13 vs. 4 range 3-8, P = .044), and a longer total hospital duration (median 14 days range 8-25 vs. 8 range 6-16, P = .023). The presence of single ventricle anatomy was associated with a lower follow-up rate at 29% than those with biventricular hearts at 64% (P = .009). Distance from the clinic did not have an effect on follow-up (P = .39).

CONCLUSION

The protocol described increased neurodevelopmental surveillance of high risk patients. Individuals that were younger and in the hospital longer were more likely to be successfully seen and comply with outpatient follow-up than those not receiving inpatient risk assessment. Patients with single ventricle anatomy may benefit from a modified follow-up schedule to improve compliance rates. Travel distance has no effect on likelihood of outpatient cardiac neurodevelopmental follow-up.

Epidemiology of Stroke in Pediatric Cardiac Surgical Patients Supported With Extracorporeal Membrane Oxygenation

BACKGROUND

Stroke is a common complication of extracorporeal membrane oxygenation (ECMO), and pediatric cardiac surgical patients may be at higher risk. Epidemiology and risk factors for stroke in these patients are not well characterized.

METHODS

We analyzed pediatric (<18 years) cardiac ECMO cases in the Extracorporeal Life Support Organization Registry from 2002 to 2013. Cardiac surgical patients were identified, and procedures were stratified according to The Society of Thoracic Surgeons morbidity categories. The primary outcome was any stroke (hemorrhagic or infarction) identified by neuroimaging. Risk factors were identified through multivariable logistic regression.

RESULTS

We analyzed 3,517 cardiac surgical patients; 81% with cyanotic disease, and 57% in high-risk categories from The Society of Thoracic Surgeons (categories 4 and 5). Overall, 12% experienced stroke while receiving ECMO, and those with stroke had greater in-hospital mortality (72% versus 51%; p < 0.0001). In multivariable analysis, neonatal status (adjusted odds ratio, 1.8; 95% confidence interval, 1.3 to 2.4), lower weight-for-age z score (adjusted odds ratio, 1.1 for each 1-point decrease; 95% confidence interval, 1.04 to 1.25), and longer ECMO duration (upper quartile [≥ 167 hours] adjusted odds ratio, 1.4; 95% confidence interval, 1.1 to 1.8) were independently associated with increased stroke risk, whereas cyanotic disease, The Society of Thoracic Surgeons category, and bypass time were not.

CONCLUSIONS

This multicenter analysis demonstrates that pediatric cardiac surgical patients on ECMO are at high risk of stroke; younger or underweight patients and those with longer ECMO duration are at greatest risk, independent of procedural complexity. Future study is necessary to determine how anticoagulation or other clinical practices can be modified to reduce stroke incidence.

Infantile postoperative encephalopathy: perioperative factors as a cause for concern

We report on 6 infants who underwent elective surgery and developed postoperative encephalopathy, which had features most consistent with intraoperative cerebral hypoperfusion. All infants were <48 weeks' postmenstrual age and underwent procedures lasting 120 to 185 minutes. Intraoperative records revealed that most of the measured systolic blood pressure (SBP) values were <60 mm Hg (the threshold for hypotension in awake infants according to the Pediatric Advanced Life Support guidelines) but that only 11% of the measured SBP values were <1 SD of the mean definition of hypotension (<45 mm Hg) as reported in a survey of members of the Society for Pediatric Anesthesia in 2009. Four infants also exhibited prolonged periods of mild hypocapnia (<35 mm Hg). One infant did not receive intraoperative dextrose. All infants developed new-onset seizures within 25 hours of administration of the anesthetic, with a predominant cerebral pathology of supratentorial watershed infarction in the border zone between the anterior, middle, and posterior cerebral arteries. Follow-up of these infants found that 1 died, 1 had profound developmental delays, 1 had minor motor delays, 2 were normal, and 1 was lost to follow-up. Although the precise cause of encephalopathy cannot be determined, it is important to consider the role that SBP hypotension (as well as hypoglycemia, hyperthermia, hyperoxia, and hypocapnia) plays during general anesthesia in young infants in the development of infantile postoperative encephalopathy. Our observations highlight the lack of evidence-based recommendations for the lower limits of adequate SBP and end-tidal carbon dioxide in anesthetized infants.

Effect of propofol on hypoxia re-oxygenation induced neuronal cell damage in vitro*

Propofol may protect neuronal cells from hypoxia re-oxygenation injury, possibly via an antioxidant actions under hypoxic conditions. This study investigated the molecular effects of propofol on hypoxia-induced cell damage using a neuronal cell line. Cultured human IMR-32 cells were exposed to propofol (30 μm) and biochemical and molecular approaches were used to assess cellular effects. Propofol significantly reduced hypoxia-mediated increases in lactate dehydrogenase, a marker of cell damage (mean (SD) for normoxia: 0.39 (0.07) a.u.; hypoxia: 0.78 (0.21) a.u.; hypoxia+propofol: 0.44 (0.17) a.u.; normoxia vs hypoxia, p<0.05; hypoxia vs hypoxia+propofol, p<0.05), reactive oxygen species and hydrogen peroxide. Propofol also diminished the morphological signs of cell damage. Increased amounts of catalase, which degrades hydrogen peroxide, were detected under hypoxic conditions. Propofol decreased the amount of catalase produced, but increased its enzymatic activity. Propofol protects neuronal cells from hypoxia re-oxygenation injury, possibly via a combined direct antioxidant effect along with induced cellular antioxidant mechanisms.

Ketamine as a neuroprotective and anti-inflammatory agent in children undergoing surgery on cardiopulmonary bypass: a pilot randomized, double-blind, placebo-controlled trial

OBJECTIVE

Infants are potentially more susceptible to cell death mediated via glutamate excitotoxicity attributed to cardiopulmonary bypass. We hypothesized that ketamine, via N-methyl D-aspartate receptor blockade and anti-inflammatory effects, would reduce central nervous system injury during cardiopulmonary bypass.

METHODS

We randomized 24 infants, without chromosomal abnormalities, to receive ketamine (2 mg/kg, n = 13) or placebo (saline, n = 11) before cardiopulmonary bypass for repair of ventricular septal defects. Plasma markers of inflammation and central nervous system injury were compared at the end of surgery, and 6, 24, and 48 hrs after surgery. Magnetic resonance imaging and spectroscopy before cardiopulmonary bypass and at the time of hospital discharge were performed in a subset of cases and controls (n = 5 in each group). Cerebral hemodynamics were monitored postoperatively using near-infrared spectroscopy, and neurodevelopmental outcomes were assessed using Bayley Scales of Infant Development-II before and 2-3 wks after surgery.

RESULTS

Statistically significant differences were noted in preoperative inspired oxygen levels, intraoperative cooling and postoperative temperature, respiratory rate, platelet count, and bicarbonate levels. The peak concentration of C-reactive protein was lower in cases compared to controls at 24 hrs (p = .048) and 48 hrs (p = .001). No significant differences were noted in the expression of various cytokines, chemokines, S100, and neuron-specific enolase between the cases and controls. Magnetic resonance imaging with spectroscopy studies showed that ketamine administration led to a significant decrease in choline and glutamate plus glutamine/creatine in frontal white matter. No statistically significant differences occurred between pre- and postoperative Bayley Scales of Infant Development-II scores.

CONCLUSIONS

We did not find any evidence for neuroprotection or neurotoxicity in our pilot study. A large, adequately powered randomized control trial is needed to discern the central nervous system effect of ketamine on the developing brain. brain.

TRIAL REGISTRATION

The trial is registered at www.ClinicalTrials.gov, NCT00556361.

Thermal protection of the newborn in resource-limited environments

Appropriate thermal protection of the newborn prevents hypothermia and its associated burden of morbidity and mortality. Yet, current global birth practices tend to not adequately address this challenge. Here, we discuss the pathophysiology of hypothermia in the newborn, its prevention and therapeutic options with particular attention to resource-limited environments. Newborns are equipped with sophisticated mechanisms of body temperature regulation. Neonatal thermoregulation is a critical function for newborn survival, regulated in the hypothalamus and mediated by endocrine pathways. Hypothermia activates cellular metabolism through shivering and non-shivering thermogenesis. In newborns, optimal temperature ranges are narrow and thermoregulatory mechanisms easily overwhelmed, particularly in premature and low-birth weight infants. Hyperthermia most commonly is associated with dehydration and potentially sepsis. The lack of thermal protection promptly leads to hypothermia, which is associated with detrimental metabolic and other pathophysiological processes. Simple thermal protection strategies are feasible at community and institutional levels in resource-limited environments. Appropriate interventions include skin-to-skin care, breastfeeding and protective clothing or devices. Due to poor provider training and limited awareness of the problem, appropriate thermal care of the newborn is often neglected in many settings. Education and appropriate devices might foster improved hypothermia management through mothers, birth attendants and health care workers. Integration of relatively simple thermal protection interventions into existing mother and child health programs can effectively prevent newborn hypothermia even in resource-limited environments.

Multimodality Neuromonitoring for Pediatric Cardiac Surgery

Brain injury remains a source of morbidity associated with congenital heart surgery. Intraoperative neuromonitoring is used by many centers to help minimize neurologic injury and improve outcomes. Neuromonitoring at our institution is performed using a combination of near-infrared spectroscopy, transcranial Doppler ultrasound, electroencephalography, and somatosensory evoked potentials. Adverse or concerning parameters instigate attempts at corrective intervention. A review of the literature regarding neuromonitoring studies in pediatric cardiac surgery shows that evidence is limited to demonstrate that intraoperative neuromonitoring is associated with improved neurologic outcomes. Further clinical research is needed to assess the utility and cost-effectiveness of intraoperative neuromonitoring for pediatric heart surgery.

Brain temperature: heat production, elimination and clinical relevance

Neurological insults are a leading cause of morbidity and mortality, both in adults and especially in children. Among possible therapeutic strategies to limit clinical cerebral damage and improve outcomes, hypothermia remains a promising and beneficial approach. However, its advantages are still debated after decades of use. Studies in adults have generated conflicting results, whereas in children recent data even suggest that hypothermia may be detrimental. Is it because brain temperature physiology is not well understood and/or not applied properly, that hypothermia fails to convince clinicians of its potential benefits? Or is it because hypothermia is not, as believed, the optimal strategy to improve outcome in patients affected with an acute neurological insult? This review article should help to explain the fundamental physiological principles of brain heat production, distribution and elimination under normal conditions and discuss why hypothermia cannot yet be recommended routinely in the management of children affected with various neurological insults.

Postoperative encephalopathy with choreoathetosis

Since the 1980s, survival of children with CHD has increased significantly with the introduction of new surgical techniques that incorporate cardiorespiratory arrest (CRA), extracorporeal circulation (ECC), and deep hypothermia. However, an increase in survival has been associated with an increase in recognized postoperative neurological complications. Postoperative encephalopathy with choreoathetosis, also known as "postpump chorea", is one of these well-defined neurological complications and was first reported in 1961. Postpump chorea is considered one of the most devastating neurological complications following cardiac surgery. However, the exact etiology and pathophysiology of this complication is unknown. Several factors may contribute to the postoperative development of choreoathetoid movements, including deep hypothermia (core body temperature < 20ºC) with total circulatory arrest, use of cardiopulmonary bypass, and variability in blood pH and PaCO(2) resulting in fluctuations in cerebral blood flow. The length of time children are affected by choreoathetoid movements and long-term neurological outcome in these children varies and largely depends upon the form of postoperative encephalopathy that they develop, described as either mild or severe. Several groups suggest that age at time of surgery plays a role in the risk of developing postpump chorea, with a tendency for older children to develop the severe persistent form.

Fluoro jade-C staining in the assessment of brain injury after deep hypothermia circulatory arrest

OBJECTIVE

To evaluate the efficacy of Fluoro Jade-C staining (FJC) in the assessment of brain injury after deep hypothermia circulatory arrest (DHCA).

METHODS

Six healthy adult miniature male pigs underwent DHCA, the rectal temperature was down to 18°C, circulation was stopped , circulatory arrest was maintained for 60 minutes. On postoperative day 1, perfusion-fixation was performed on brain tissue. Cerebral cortex, hippocampus, cerebellum were taken for sampling. FJC, hematoxylin-eosin staining (HE), nissl staining (NISSL), terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) were performed to detect the histological and pathological changes. Histological scores of all slices were ranked. Comparison between the FJC and other techniques was done by analysis of variance (ANOVA) according to histological scores.

RESULTS

All animals survived the operation. On the cerebral cortex, in comparison of FJC between HE, NISSL and TUNEL, the p value was 0.90, 0.40, 0.16 respectively (p>0.05). On the hippocampus, the comparison of FJC with HE, NISSL and TUNEL had a p value of 0.12, 0.23, 0.62 respectively (p>0.05). On the cerebellum, in comparing FJC with HE, NISSL and TUNEL, the p value was 0.96, 0.77, 0.96 respectively (p>0.05). On representative regions, the results of FJC were in accordance with that of TUNEL, NISSL and HE. Furthermore, ascertainment of brain injury is easier with FJC.

CONCLUSION

FJC is a reliable and convenient method to assess brain injury after DHCA.

New approaches to neuroprotection in infant heart surgery

Advances in surgical techniques and perioperative management have led to dramatic improvements in outcomes for children with complex congenital heart disease (CHD). As the number of survivors continues to grow, clinicians are becoming increasingly aware that adverse neurodevelopmental outcomes after surgical repair of CHD represent a significant cause of morbidity, with widespread neuropsychologic deficits in as many as 50% of these children by the time they reach school age. Modifications of intraoperative management have yet to measurably impact long-term neurologic outcomes. However, exciting advances in our understanding of the underlying mechanisms of cellular injury and of the events that mediate endogenous cellular protection have provided a variety of new potential targets for the assessment, prevention, and treatment of neurologic injury in patients with CHD. In this review, we will discuss the unique challenges to developing neuroprotective strategies in children with CHD and consider how multisystem approaches to neuroprotection, such as ischemic preconditioning, will be the focus of ongoing efforts to develop new diagnostic tools and therapies. Although significant challenges remain, tremendous opportunity exists for the development of diagnostic and therapeutic interventions that can serve to limit neurologic injury and ultimately improve outcomes for infants and children with CHD.

Acute brain injury and therapeutic hypothermia in the PICU: A rehabilitation perspective

Acquired brain injury from traumatic brain injury, cardiac arrest (CA), stroke, and central nervous system infection is a leading cause of morbidity and mortality in the pediatric population and reason for admission to inpatient rehabilitation. Therapeutic hypothermia is the only intervention shown to have efficacy from bench to bedside in improving neurological outcome after birth asphyxia and adult arrhythmia-induced CA, thought to be due to its multiple mechanisms of action. Research to determine if therapeutic hypothermia should be applied to other causes of brain injury and how to best apply it is underway in children and adults. Changes in clinical practice in the hospitalized brain-injured child may have effects on rehabilitation referral practices, goals and strategies of therapies offered, and may increase the degree of complex medical problems seen in children referred to inpatient rehabilitation.

Neurological complications associated with the treatment of patients with congenital cardiac disease: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease

A complication is an event or occurrence that is associated with a disease or a healthcare intervention, is a departure from the desired course of events, and may cause, or be associated with suboptimal outcome. A complication does not necessarily represent a breech in the standard of care that constitutes medical negligence or medical malpractice. An operative or procedural complication is any complication, regardless of cause, occurring (1) within 30 days after surgery or intervention in or out of the hospital, or (2) after 30 days during the same hospitalization subsequent to the operation or intervention. Operative and procedural complications include both intraoperative/intraprocedural complications and postoperative/postprocedural complications in this time interval. The MultiSocietal Database Committee for Pediatric and Congenital Heart Disease has set forth a comprehensive list of complications associated with the treatment of patients with congenital cardiac disease, related to cardiac, pulmonary, renal, haematological, infectious, neurological, gastrointestinal, and endocrine systems, as well as those related to the management of anaesthesia and perfusion, and the transplantation of thoracic organs. The objective of this manuscript is to examine the definitions of operative morbidity as they relate specifically to the neurological system. These specific definitions and terms will be used to track morbidity associated with surgical and transcatheter interventions and other forms of therapy in a common language across many separate databases. Although neurological injury and adverse neurodevelopmental outcome can follow procedures for congenital cardiac defects, much of the variability in neurological outcome is now recognized to be more related to patient specific factors rather than procedural factors. Additionally, the recognition of pre and postoperative neurological morbidity requires procedures and imaging modalities that can be resource-intensive to acquire and analyze, and little is known or described about variations in "sampling rate" from centre to centre. The purpose of this effort is to propose an initial set of consensus definitions for neurological complications following congenital cardiac surgery and intervention. Given the dramatic advances in understanding achieved to date, and those yet to occur, this effort is explicitly recognized as only the initial first step of a process that must remain iterative. This list is a component of a systems-based compendium of complications that may help standardize terminology and possibly enhance the study and quantification of morbidity in patients with congenital cardiac malformations. Clinicians caring for patients with congenital cardiac disease may be able to use this list for databases, initiatives to improve quality, reporting of complications, and comparing strategies of treatment.