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1.  Evolution of Encephalopathy during Whole Body Hypothermia for Neonatal Hypoxic-Ischemic Encephalopathy 
The Journal of Pediatrics  2011;160(4):567-572.e3.
Objective
To examine the predictive ability of stage of hypoxic-ischemic encephalopathy (HIE) for death or moderate/severe disability at 18 months among neonates undergoing hypothermia.
Study design
Stage of encephalopathy was evaluated at <6 hr of age, during study intervention and at discharge among 204 participants in the NICHD Neonatal Research Network Trial of whole body hypothermia for HIE. HIE was examined as a predictor of outcome by regression models.
Results
Moderate and severe HIE occurred at <6 hrs of age among 68% and 32% of 101 hypothermia group infants and 60% and 40% of 103 control group infants, respectively. At 24 and 48 hrs of study intervention, infants in the hypothermia group had less severe HIE than infants in the control group. Persistence of severe HIE at 72 hrs increased the risk of death or disability after controlling for treatment group. The discharge exam improved the predictive value of stage of HIE at < 6hrs for death/disability.
Conclusions
On serial neurological examinations, improvement in stage of HIE was associated with cooling. Persistence of severe HIE at 72 hours and an abnormal neurological exam at discharge was associated with a greater risk of death or disability.
doi:10.1016/j.jpeds.2011.09.018
PMCID: PMC3299861  PMID: 22050871
Neurological examinations; neonates; clinical biomarker; death; disability
2.  Brain injury following trial of hypothermia for neonatal hypoxic–ischaemic encephalopathy 
Objective
The objective of our study was to examine the relationship between brain injury and outcome following neonatal hypoxic–ischaemic encephalopathy treated with hypothermia.
Design and patients
Neonatal MRI scans were evaluated in the National Institute of Child Health and Human Development (NICHD) randomised controlled trial of whole-body hypothermia and each infant was categorised based upon the pattern of brain injury on the MRI findings. Brain injury patterns were assessed as a marker of death or disability at 18–22 months of age.
Results
Scans were obtained on 136 of 208 trial participants (65%); 73 in the hypothermia and 63 in the control group. Normal scans were noted in 38 of 73 infants (52%) in the hypothermia group and 22 of 63 infants (35%) in the control group. Infants in the hypothermia group had fewer areas of infarction (12%) compared to infants in the control group (22%). Fifty-one of the 136 infants died or had moderate or severe disability at 18 months. The brain injury pattern correlated with outcome of death or disability and with disability among survivors. Each point increase in the severity of the pattern of brain injury was independently associated with a twofold increase in the odds of death or disability.
Conclusions
Fewer areas of infarction and a trend towards more normal scans were noted in brain MRI following whole-body hypothermia. Presence of the NICHD pattern of brain injury is a marker of death or moderate or severe disability at 18–22 months following hypothermia for neonatal encephalopathy.
doi:10.1136/archdischild-2011-301524
PMCID: PMC3722585  PMID: 23080477
3.  Clinical Seizures in Neonatal Hypoxic-Ischemic Encephalopathy Have No Independent Impact on Neurodevelopmental Outcome: Secondary Analyses of Data from the Neonatal Research Network Hypothermia Trial 
Journal of Child Neurology  2010;26(3):322-328.
It remains controversial as to whether neonatal seizures have additional direct effects on the developing brain separate from the severity of the underlying encephalopathy. Using data collected from infants diagnosed with hypoxic-ischemic encephalopathy, and who were enrolled in an National Institute of Child Health and Human Development trial of hypothermia, we analyzed associations between neonatal clinical seizures and outcomes at 18 months of age. Of the 208 infants enrolled, 102 received whole body hypothermia and 106 were controls. Clinical seizures were generally noted during the first 4 days of life and rarely afterward. When adjustment was made for study treatment and severity of encephalopathy, seizures were not associated with death, or moderate or severe disability, or lower Bayley Mental Development Index scores at 18 months of life. Among infants diagnosed with hypoxic-ischemic encephalopathy, the mortality and morbidity often attributed to neonatal seizures can be better explained by the underlying severity of encephalopathy.
doi:10.1177/0883073810380915
PMCID: PMC3290332  PMID: 20921569
neonatal seizures; whole-body hypothermia; neurodevelopmental outcome; hypoxic-ischemic encephalopathy
4.  Childhood Outcomes after Hypothermia for Neonatal Encephalopathy 
The New England journal of medicine  2012;366(22):2085-2092.
BACKGROUND
We previously reported early results of a randomized trial of whole-body hypothermia for neonatal hypoxic–ischemic encephalopathy showing a significant reduction in the rate of death or moderate or severe disability at 18 to 22 months of age. Long-term outcomes are now available.
METHODS
In the original trial, we assigned infants with moderate or severe encephalopathy to usual care (the control group) or whole-body cooling to an esophageal temperature of 33.5°C for 72 hours, followed by slow rewarming (the hypothermia group). We evaluated cognitive, attention and executive, and visuospatial function; neurologic outcomes; and physical and psychosocial health among participants at 6 to 7 years of age. The primary outcome of the present analyses was death or an IQ score below 70.
RESULTS
Of the 208 trial participants, primary outcome data were available for 190. Of the 97 children in the hypothermia group and the 93 children in the control group, death or an IQ score below 70 occurred in 46 (47%) and 58 (62%), respectively (P = 0.06); death occurred in 27 (28%) and 41 (44%) (P = 0.04); and death or severe disability occurred in 38 (41%) and 53 (60%) (P = 0.03). Other outcome data were available for the 122 surviving children, 70 in the hypothermia group and 52 in the control group. Moderate or severe disability occurred in 24 of 69 children (35%) and 19 of 50 children (38%), respectively (P = 0.87). Attention–executive dysfunction occurred in 4% and 13%, respectively, of children receiving hypothermia and those receiving usual care (P = 0.19), and visuospatial dysfunction occurred in 4% and 3% (P = 0.80).
CONCLUSIONS
The rate of the combined end point of death or an IQ score of less than 70 at 6 to 7 years of age was lower among children undergoing whole-body hypothermia than among those undergoing usual care, but the differences were not significant. However, hypothermia resulted in lower death rates and did not increase rates of severe disability among survivors. (Funded by the National Institutes of Health and the Eunice Kennedy Shriver NICHD Neonatal Research Network; ClinicalTrials.gov number, NCT00005772.)
doi:10.1056/NEJMoa1112066
PMCID: PMC3459579  PMID: 22646631
5.  Hypothermia for hypoxic–ischemic encephalopathy 
Moderate to severe hypoxic–ischemic injury in newborn infants, manifested as encephalopathy immediately or within hours after birth, is associated with a high risk of either death or a lifetime with disability. In recent multicenter clinical trials, hypothermia initiated within the first 6 postnatal hours has emerged as a therapy that reduces the risk of death or impairment among infants with hypoxic–ischemic encephalopathy. Prior to hypothermia, no therapies directly targeting neonatal encephalopathy secondary to hypoxic–ischemic injury had convincing evidence of efficacy. Hypothermia therapy is now becoming increasingly available at tertiary centers. Despite the deserved enthusiasm for hypothermia, obstetric and neonatology caregivers, as well as society at large, must be reminded that in the clinical trials more than 40% of cooled infants died or survived with impairment. Although hypothermia is an evidence-based therapy, additional discoveries are needed to further improve outcome after HIE. In this article, we briefly present the epidemiology of neonatal encephalopathy due to hypoxic–ischemic injury, describe the rationale for the use of hypothermia therapy for hypoxic–ischemic encephalopathy, and present results of the clinical trials that have demonstrated the efficacy of hypothermia. We also present findings noted during and after these trials that will guide care and direct research for this devastating problem.
doi:10.1586/eog.10.7
PMCID: PMC2897079  PMID: 20625441
HIE; hyperthermia; hypothermia; hypoxic–ischemic encephalopathy; neonate; perinatal asphyxia
6.  Hypocarbia and Adverse Outcome in Neonatal Hypoxic-Ischemic Encephalopathy 
The Journal of pediatrics  2010;158(5):752-758.e1.
Objective
To evaluate the association between early hypocarbia and 18-22 month outcome among neonates with hypoxic-ischemic encephalopathy (HIE).
Study design
Data from the NICHD NRN randomized controlled trial of whole body hypothermia for neonatal HIE were used for this secondary observational study. Infants (n=204) had multiple blood gases recorded from birth-12h of study intervention (hypothermia vs. intensive care alone). The relationship between hypocarbia and outcome (death/disability at 18-22 months) was evaluated by unadjusted and adjusted analyses examining minimum PCO2 and cumulative exposure to PCO2 <35 mmHg. The relationship between cumulative PCO2 <35 mmHg (calculated as the difference between 35mmHg and the sampled PCO2 multiplied by the duration of time spent <35 mmHg) and outcome was evaluated by level of exposure (none-high) using a multiple logistic regression analysis with adjustments for pH, level of encephalopathy, treatment group (± hypothermia), time to spontaneous respiration and ventilator days; results were expressed as OR and 95% confidence intervals. Alternative models of CO2 concentration were explored to account for fluctuations in CO2.
Results
Both minimum PCO2 and cumulative PCO2 <35mmHg were associated with poor outcome (P<0.05). Moreover, death/disability increased with greater cumulative exposure to PCO2 <35mmHg.
Conclusion
Hypocarbia is associated with poor outcome following HIE.
doi:10.1016/j.jpeds.2010.10.019
PMCID: PMC3229432  PMID: 21146184
hypocarbia; hypoxic ischemic encephalopathy; whole body hypothermia; outcome; neurodevelopmental impairment
7.  Therapeutic Hypothermia for Neonatal Encephalopathy 
Opinion statement
Neonatal Hypoxic-ischemic encephalopathy in full term infants has been associated with a high risk for morbidity and mortality. The patho-physiology of brain injury following hypoxia-ischemia, noted in preclinical models, is a cascade of events resulting from excitotoxic and oxidative injury culminating in cell death. Hypothermia has been noted to be protective by inhibiting various events in the cascade of injury. Major randomized clinical trials in neonatal HIE have demonstrated reduction in death and disability and continued safety and efficacy of neuroprotection in childhood. There is now clinical and imaging evidence for hypothermia as neuroprotection. Hypothermia should be offered to term infants with either severe acidosis at birth or resuscitation needing continued ventilation and evidence of either moderate or severe encephalopathy within 6 hours of birth. The target temperature should be 33° to 34 °C and duration of cooling should be 72 hours, as per the published trials. Rewarming should be slow, at 0.5 °C per hour. Infants should have serial neurological examinations during and at the end of cooling and at discharge. Multiorgan function should be supported and hypocarbia should be avoided during ventilator therapy. If available, the amplitude integrated EEG should be obtained prior to cooling and following rewarming. All infants should have magnetic resonance brain imaging studies within 1 to 2 weeks of age. Information from the neurological examination, aEEG and MRI studies will be helpful in discussing prognosis with parents. All infants should be followed for a minimum of 18 months to evaluate growth parameters and neurodevelopment al outcome.
doi:10.1007/s11940-012-0200-y
PMCID: PMC3519960  PMID: 23007949
Therapeutic hypothermia; Neonatal encephalopathy; Term infants; Neonatal hypoxic-ischemic encephalopathy; Pathophysiology; Neurodevelopmental outcome; Neuroprotection; Head cooling; Whole body cooling; Randomized controlled trials; Knowledge gaps; Adjuvant therapies; Treatment
8.  A systematic review of cooling for neuroprotection in neonates with hypoxic ischemic encephalopathy – are we there yet? 
BMC Pediatrics  2007;7:30.
Background
The objective of this study was to systematically review randomized trials assessing therapeutic hypothermia as a treatment for term neonates with hypoxic ischemic encephalopathy.
Methods
The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL databases, reference lists of identified studies, and proceedings of the Pediatric Academic Societies were searched in July 2006. Randomized trials assessing the effect of therapeutic hypothermia by either selective head cooling or whole body cooling in term neonates were eligible for inclusion in the meta-analysis. The primary outcome was death or neurodevelopmental disability at ≥ 18 months.
Results
Five trials involving 552 neonates were included in the analysis. Cooling techniques and the definition and severity of neurodevelopmental disability differed between studies. Overall, there is evidence of a significant effect of therapeutic hypothermia on the primary composite outcome of death or disability (RR: 0.78, 95% CI: 0.66, 0.92, NNT: 8, 95% CI: 5, 20) as well as on the single outcomes of mortality (RR: 0.75, 95% CI: 0.59, 0.96) and neurodevelopmental disability at 18 to 22 months (RR: 0.72, 95% CI: 0.53, 0.98). Adverse effects include benign sinus bradycardia (RR: 7.42, 95% CI: 2.52, 21.87) and thrombocytopenia (RR: 1.47, 95% CI: 1.07, 2.03, NNH: 8) without deleterious consequences.
Conclusion
In general, therapeutic hypothermia seems to have a beneficial effect on the outcome of term neonates with moderate to severe hypoxic ischemic encephalopathy. Despite the methodological differences between trials, wide confidence intervals, and the lack of follow-up data beyond the second year of life, the consistency of the results is encouraging. Further research is necessary to minimize the uncertainty regarding efficacy and safety of any specific technique of cooling for any specific population.
doi:10.1186/1471-2431-7-30
PMCID: PMC2031882  PMID: 17784966
9.  Temperature Profile and Outcomes of Neonates Undergoing Whole Body Hypothermia for Neonatal Hypoxic-Ischemic Encephalopathy 
BACKGROUND
Decreases below target temperature were noted among neonates undergoing cooling in the NICHD Neonatal Research Network Trial of whole body hypothermia for neonatal hypoxic-ischemic encephalopathy.
OBJECTIVE
To examine the temperature profile and impact on outcome among ≥ 36 week gestation neonates randomized at ≤ 6 hours of age targeting esophageal temperature of 33.5°C for 72 hours.
DESIGN/SETTING/PATIENTS
Infants with intermittent temperatures recorded < 32.0°C during induction and maintenance of cooling were compared to all other cooled infants and relationship with outcome at 18 months was evaluated.
RESULTS
There were no differences in stage of encephalopathy, acidosis, or 10 minute Apgar scores between infants with temperatures < 32.0°C during induction (n=33) or maintenance (n=10) and all other infants who were cooled (n=58); however birth weight was lower and need for blood pressure support higher among infants with temperatures < 32.0 °C compared to all other cooled infants. No increase in acute adverse events were noted among infants with temperatures < 32.0 °C and hours spent < 32°C were not associated with the primary outcome of death or moderate/severe disability or the Bayley II Mental Developmental Index at 18 months.
CONCLUSION
Term infants with a lower birth weight are at risk for decreasing temperatures < 32.0°C while undergoing body cooling using a servo controlled system. This information suggests extra caution during the application of hypothermia as these lower birth weight infants are at risk for overcooling. Our findings may assist in planning additional trials of lower target temperature for neonatal hypoxic-ischemic encephalopathy.
doi:10.1097/PCC.0b013e31821926bc
PMCID: PMC3161166  PMID: 21499182
temperature; hypothermia; newborn; hypoxia-ischemia; encephalopathy; whole-body cooling
10.  The Use of Hypothermia Therapy in Traumatic Ischemic / Reperfusional Brain Injury: Review of the Literatures 
Therapeutic mild hypothermia has been used widely in brain injury. It has evaluated in numerous clinical trials, and there is strong evidence for the use of hypothermia in treating patients with several types of ischemic / reperfusional (I/R) injuries, examples being cardiac arrest and neonatal hypoxic-ischemic encephalopathy.
In spite of many basic research projects demonstrating effectiveness, therapeutic hypothermia has not been proven effective for the heterogeneous group of traumatic brain injury patients in multicenter clinical trials. In the latest clinical trial, however, researchers were able to demonstrate the significant beneficial effects of hypothermia in one specific group; patients with mass evacuated lesions. This suggested that mild therapeutic hypothermia might be effective for I/R related traumatic brain injury.
In this article we have reviewed much of the previous literature concerning the mechanisms of I/R injury to the protective effects of mild therapeutic hypothermia.
doi:10.1089/ther.2011.0012
PMCID: PMC3579497  PMID: 23439678
brain hypothermia; brain injury; ischemia; reperfusion; subdural hematoma
11.  The Use of Hypothermia Therapy in Traumatic Ischemic/Reperfusional Brain Injury: Review of the Literatures 
Therapeutic mild hypothermia has been widely used in brain injury. It has been evaluated in numerous clinical trials, and there is strong evidence for the use of hypothermia in treating patients with several types of ischemic/reperfusional (I/R) injuries, the examples being cardiac arrest and neonatal hypoxic-ischemic encephalopathy. In spite of many basic research projects demonstrating effectiveness, therapeutic hypothermia has not been proved effective for the heterogeneous group of patients with traumatic brain injury (TBI) in multicenter clinical trials. In the latest clinical trial, however, researchers were able to demonstrate the significant beneficial effects of hypothermia in one specific group; patients with mass evacuated lesions. This suggested that mild therapeutic hypothermia might be effective for I/R related TBI. In this article, we have reviewed much of the previous literature concerning the mechanisms of I/R injury to the protective effects of mild therapeutic hypothermia.
doi:10.1089/ther.2011.0012
PMCID: PMC3579497  PMID: 23439678
12.  Neonatal Encephalopathy: Treatment with Hypothermia 
Journal of neurotrauma  2009;26(3):437-443.
In this article, the role of hypothermia and neuroprotection for neonatal encephalopathy will be discussed. The incidence of encephalopathy due to hypoxia ischemia as well as the pathophysiology will be presented. The diagnosis of encephalopathy in full-term neonates will be discussed. The current management of brain injury that occurs with hypoxia ischemia and the role of hypothermia in preventing brain injury in fetal and neonatal animal models will be reviewed. The current data from randomized control trials of hypothermia as neuroprotection for full-term infants will be presented along with the results of meta-analyses of these trials. Lastly, the status of ongoing neonatal hypothermia trials will be summarized.
doi:10.1089/neu.2008.0678
PMCID: PMC2828322  PMID: 19281415
encephalopathy; hypothermia; hypoxia-ischemia; neonate
13.  Neonatal Encephalopathy: Treatment with Hypothermia 
Journal of Neurotrauma  2009;26(3):437-443.
Abstract
In this article, the role of hypothermia and neuroprotection for neonatal encephalopathy will be discussed. The incidence of encephalopathy due to hypoxia ischemia as well as the pathophysiology will be presented. The diagnosis of encephalopathy in full-term neonates will be discussed. The current management of brain injury that occurs with hypoxia ischemia and the role of hypothermia in preventing brain injury in fetal and neonatal animal models will be reviewed. The current data from randomized control trials of hypothermia as neuroprotection for full-term infants will be presented along with the results of meta-analyses of these trials. Lastly, the status of ongoing neonatal hypothermia trials will be summarized.
doi:10.1089/neu.2008.0678
PMCID: PMC2828322  PMID: 19281415
encephalopathy; hypothermia; hypoxia-ischemia; neonate
14.  Septicemia in a Neonate following Therapeutic Hypothermia: The Literature Review of Evidence 
Case Reports in Pediatrics  2013;2013:514232.
We report a term neonate with hypoxic ischemic encephalopathy who underwent a 72-hour therapeutic hypothermia. He developed unstable body temperature associated with coagulase negative staphylococcus septicemia 2 weeks later which was promptly treated with intravenous antibiotics and made a good recovery. PubMed (a service of the U.S. National Library of Medicine) was searched for the terms “therapeutic hypothermia” and “septicemia,” with limits activated (humans, English, age 0–18 years). There were only 6 randomized controlled trials, 1 non-randomized controlled trial, 1 retrospective cohort, and 1 case-control trial, which showed no definite evidence of increased risk of septicemia or neutrophil dysfunction in infants following hypothermia therapy.
doi:10.1155/2013/514232
PMCID: PMC3789282  PMID: 24159400
15.  Phenobarbital Augments Hypothermic Neuroprotection 
Pediatric research  2010;67(5):532-537.
Seizures are associated with adverse outcome in infants with hypoxic-ischemic encephalopathy. We hypothesized that early administration of the anticonvulsant phenobarbital after cerebral hypoxia-ischemia could enhance the neuroprotective efficacy of delayed-onset hypothermia. We tested this hypothesis in a neonatal rodent model. Seven-day-old rats (n=104) underwent right carotid ligation, followed by 90 min 8%O2 exposure; 15 min later, they received injections of phenobarbital (40 mg/kg) or saline. One or 3h later, all were treated with hypothermia (30°C, 3h). Function and neuropathology were evaluated after 7 days (“early outcomes”) or 1 month (“late outcomes”). Early outcome assessment demonstrated better sensorimotor performance and less cortical damage in phenobarbital-treated groups; there were no differences between groups in which the hypothermia delay was shortened from 3h to 1h. Late outcome assessment confirmed sustained benefits of phenobarbital+hypothermia treatment; sensorimotor performance was better (persistent attenuation of contralateral forepaw placing deficits and absence of contralateral forepaw neglect); neuropathology scores were lower (medians, phenobarbital 2, saline 8.5, p<0.05), and less ipsilateral cerebral hemisphere %Damage (mean±SD, 11±17 vs. 28±22, p<0.05). These results suggest that early post-hypoxia-ischemia administration of phenobarbital may augment the neuroprotective efficacy of therapeutic hypothermia.
doi:10.1203/PDR.0b013e3181d4ff4d
PMCID: PMC2906127  PMID: 20098339
16.  Volumetric and Anatomic MRI for Hypoxic-Ischemic Encephalopathy: Relationship to Hypothermia Therapy and Neurosensory Impairments 
Objective
To relate volumetric MRI findings to hypothermia therapy and neurosensory impairments.
Study Design
Newborns ≥ 36 weeks’ gestation with hypoxic-ischemic encephalopathy who participated in the NICHD hypothermia randomized trial at our center were eligible. We determined the relationship between hypothermia treatment and usual care (control) to absolute and relative cerebral tissue volumes. Further, we correlated brain volumes with death or neurosensory impairments at 18 to 22 months.
Results
Both treatment groups were comparable before randomization. Total brain tissue volumes did not differ in relation to treatment assignment. However, relative volumes of subcortical white matter were significantly larger in hypothermia-treated than control infants. Furthermore, relative total brain volumes correlated significantly with death or neurosensory impairments. Relative volumes of the cortical gray and subcortical white matter also correlated significantly with Bayley Scales psychomotor development index.
Conclusion
Selected volumetric MRI findings correlated with hypothermia therapy and neurosensory impairments. Larger studies utilizing MRI brain volumes as a secondary outcome measure are needed.
doi:10.1038/jp.2008.184
PMCID: PMC2740332  PMID: 19020525
hypoxia-ischemia, brain; hypothermia, induced; magnetic resonance imaging; cerebral palsy; outcome assessment
17.  Effect of inborn vs. outborn delivery on neurodevelopmental outcomes in infants with hypoxic–ischemic encephalopathy: secondary analyses of the NICHD whole-body cooling trial 
Pediatric research  2012;72(4):414-419.
BACKGROUND
The effect of birth location on hypothermia-related outcomes has not been rigorously examined in the literature. In this study, we determined whether birth location had an impact on the benefits of whole-body cooling to 33.5 °C for 72 h in term infants (n = 208) with hypoxic–ischemic encephalopathy (HIE) who participated in the Neonatal Research Network (NRN) randomized controlled trial.
METHODS
Heterogeneity by birth location was examined with respect to cooling treatment for the 18-mo primary outcomes (death, moderate disability, severe disability) and secondary outcomes (death, components of disability), and in-hospital organ dysfunction. Logistic regression models were used to generate adjusted odds ratios.
RESULTS
Infants bom at a location other than an NRN center (outborn) (n = 93) experienced significant delays in initiation of therapy (mean (SD): 5.5 (1.1) vs. 4.4 (1.2) h), lower baseline temperatures (36.6 (1.2) vs. 37.1 (0.9) °C), and more severe HIE (43 vs. 29%) than infants born in an NRN center (inborn) (n = 115). Maternal education <12 y (50 vs. 14%) and African-American ethnicity (43 vs. 25%) were more common in the inborn group. When adjusted for NRN center and HIE severity, there were no significant differences in 18-mo outcomes or in-hospital organ dysfunction between inborn and outborn infants.
CONCLUSION
Although limited by sample size and some differences in baseline characteristics, the study showed that birth location does not appear to modify the treatment effect of hypothermia after HIE.
doi:10.1038/pr.2012.103
PMCID: PMC3730811  PMID: 22914450
18.  Assessment of brain tissue injury after moderate hypothermia in neonates with hypoxic–ischaemic encephalopathy: a nested substudy of a randomised controlled trial 
Lancet Neurology  2010;9(1):39-45.
Summary
Background
Moderate hypothermia in neonates with hypoxic–ischaemic encephalopathy might improve survival and neurological outcomes at up to 18 months of age, although complete neurological assessment at this age is difficult. To ascertain more precisely the effect of therapeutic hypothermia on neonatal cerebral injury, we assessed cerebral lesions on MRI scans of infants who participated in the Total Body Hypothermia for Neonatal Encephalopathy (TOBY) trial.
Methods
In the TOBY trial hypoxic–ischaemic encephalopathy was graded clinically according to the changes seen on amplitude integrated EEG, and infants were randomly assigned to intensive care with or without cooling by central telephone randomisation. The relation between allocation to hypothermia or normothermia and cerebral lesions was assessed by logistic regression with perinatal factors as covariates, and adjusted odds ratios (ORs) were calculated. The TOBY trial is registered, number ISRCTN 89547571.
Findings
325 infants were recruited in the TOBY trial between 2002 and 2006. Images were available for analysis from 131 infants. Therapeutic hypothermia was associated with a reduction in lesions in the basal ganglia or thalamus (OR 0·36, 95% CI 0·15–0·84; p=0·02), white matter (0·30, 0·12–0·77; p=0·01), and abnormal posterior limb of the internal capsule (0·38, 0·17–0·85; p=0·02). Compared with non-cooled infants, cooled infants had fewer scans that were predictive of later neuromotor abnormalities (0·41, 0·18–0·91; p=0·03) and were more likely to have normal scans (2·81, 1·13–6·93; p=0·03). The accuracy of prediction by MRI of death or disability to 18 months of age was 0·84 (0·74–0·94) in the cooled group and 0·81 (0·71–0·91) in the non-cooled group.
Interpretation
Therapeutic hypothermia decreases brain tissue injury in infants with hypoxic–ischaemic encephalopathy. The predictive value of MRI for subsequent neurological impairment is not affected by therapeutic hypothermia.
Funding
UK Medical Research Council; UK Department of Health.
doi:10.1016/S1474-4422(09)70295-9
PMCID: PMC2795146  PMID: 19896902
19.  Synergistic neuroprotective therapies with hypothermia 
summary
Neuroprotection is a major health care priority, given the enormous burden of human suffering and financial cost caused by perinatal brain damage. With the advent of hypothermia as therapy for term hypoxic–ischemic encephalopathy, there is hope for repair and protection of the brain after a profound neonatal insult. However, it is clear from the published clinical trials and animal studies that hypothermia alone will not provide complete protection or stimulate the repair that is necessary for normal neurodevelopmental outcome. This review critically discusses drugs used to treat seizures after hypoxia–ischemia in the neonate with attention to evidence of possible synergies for therapy. In addition, other agents such as xenon, N-acetylcysteine, erythropoietin, melatonin and cannabinoids are discussed as future potential therapeutic agents that might augment protection from hypothermia. Finally, compounds that might damage the developing brain or counteract the neuroprotective effects of hypothermia are discussed.
doi:10.1016/j.siny.2010.02.002
PMCID: PMC2892736  PMID: 20207600
Anticonvulsants; Hypoxia; Ischemia; Neuroprotection; Repair; Seizures
20.  Physiologic and pharmacologic considerations for hypothermia therapy in neonates 
With mounting evidence that hypothermia is neuroprotective in newborns with hypoxic-ischemic encephalopathy (HIE), an increasing number of centers are offering this therapy. Hypothermia is associated with a wide range of physiologic changes affecting every organ system, and awareness of these effects is essential for optimum patient management. Lowering the core temperature also alters pharmacokinetic and pharmacodynamic properties of medications commonly used in asphyxiated neonates, necessitating close attention to drug efficacy and side effects. Rewarming introduces additional risks and challenges as the hypothermia-associated physiologic and pharmacologic changes are reversed. In this review we provide an organ system-based assessment of physiologic changes associated with hypothermia. We also summarize evidence from randomized controlled trials showing lack of serious adverse effects of moderate hypothermia therapy in term and near-term newborns with moderate-to-severe HIE. Finally, we review the effects of hypothermia on drug metabolism and clearance based on studies in animal models and human adults, and limited data from neonates.
doi:10.1038/jp.2010.146
PMCID: PMC3552186  PMID: 21183927
hypothermia; hypoxic-ischemic encephalopathy; neonate; pharmacologic effect; physiology effect; rewarming
21.  Early Antioxidant Treatment and Delayed Hypothermia After Hypoxia-Ischemia Have No Additive Neuroprotection in Newborn Pigs 
Anesthesia and analgesia  2012;115(3):627-637.
Background
The implementation and clinical efficacy of hypothermia in neonatal hypoxic-ischemic (HI) encephalopathy are limited, in part, by the delay in instituting hypothermia and access to equipment. In a piglet model of HI, half of the neurons in putamen already showed ischemic cytopathology by 6 hours of recovery. We tested the hypothesis that treatment with the superoxide dismutase-catalase mimetic EUK-134 at 30 minutes of recovery provides additive neuronal protection when combined with one day of whole body hypothermia implemented 4 hours after resuscitation.
Methods
Anesthetized piglets were subjected to 40 minutes of hypoxia (10% inspired oxygen) followed by 7 minutes of airway occlusion and resuscitation. Body temperature was maintained at 38.5°C in normothermic groups and at 34°C in hypothermic groups. All groups were mechanically ventilated, sedated, and received muscle relaxants during the first day of recovery. Neuropathology was assessed by profile and stereological cell counting methods.
Results
At 10 days of recovery, neuronal viability in putamen of a normothermic group treated with saline vehicle was reduced to 17±6% (±95% confidence interval) of the value in a sham-operated control group (100±15%). Intravenous infusion of EUK-134 (2.5 mg/kg at 30 minutes of recovery + 1.25 mg/kg/h until 4 hours of recovery) with normothermic recovery resulted in 40±12% viable neurons in putamen. Treatment with saline vehicle followed by delayed hypothermia resulted in partial protection (46±15%). Combining early EUK-134 treatment with delayed hypothermia also produced partial protection (47±18%) that was not significantly greater than single treatment with EUK-134 (confidence interval of difference: −15% to 29%) or delayed hypothermia (−16% to 19%). Furthermore, no additive neuroprotection was detected in caudate nucleus or parasagittal neocortex, where neuronal loss was less severe.
Conclusions
We conclude that early treatment with this antioxidant does not substantially enhance the therapeutic benefit of delayed hypothermia in protecting highly vulnerable neurons in HI-insulted newborns, possibly because basal ganglia neurons are already undergoing irreversible cell death signaling by the time EUK-134 is administered or because this compound and hypothermia attenuate similar mechanisms of injury.
doi:10.1213/ANE.0b013e31825d3600
PMCID: PMC3425722  PMID: 22745113
22.  Therapeutic hypothermia on neonatal transport: 4-year experience in a single NICU 
Journal of Perinatology  2009;30(5):324-329.
Objective:
Therapeutic hypothermia instituted within 6 h of birth has been shown to improve neurodevelopmental outcomes in term newborns with moderate–to–severe hypoxic–ischemic encephalopathy (HIE). The majority of infants who would benefit from cooling are born at centers that do not offer the therapy, and adding the time for transport will result in delays in therapy, that may lead to suboptimal or no neuroprotection for some patients. Our objective was to evaluate the effect of our center's experience with therapeutic hypothermia on neonatal transport.
Study Design:
Retrospective review of all cases of therapeutic hypothermia at a single neonatal intensive care unit from 2005 to 2009.
Result:
Of 50 infants with HIE treated with hypothermia, 40 were outborn and 35 were cooled on transport. The majority of patients were passively cooled by the referring clinicians, then actively cooled by our transport team. Overcooling to <32 °C occurred in 34% of patients, but there were no significant differences in admission vital signs or laboratory values between overcooled and appropriately cooled infants. The average time after birth of initiation of passive cooling was 1.4 h and active cooling was 2.7 h compared with the time of admission to our unit of 5.9 h.
Conclusion:
We discuss the important aspects of our program, including the education of referring and receiving clinicians and avoidance of overcooling.
doi:10.1038/jp.2009.168
PMCID: PMC2864418  PMID: 19847186
hypothermia; hypoxic-ischemic encephalopathy; neontal transport; neuroprotection; birth asphyxia
23.  Heart Rate and Arterial Pressure Changes during Whole-Body Deep Hypothermia 
ISRN Pediatrics  2013;2013:140213.
Whole-body deep hypothermia (DH) could be a new therapeutic strategy for asphyxiated newborn. This retrospective study describes how DH modified the heart rate and arterial blood pressure if compared to mild hypothermia (MH). Fourteen in DH and 17 in MH were cooled within the first six hours of life and for the following 72 hours. Hypothermia criteria were gestational age ≥36 weeks; birth weight ≥1800 g; clinical signs of moderate/severe hypoxic-ischemic encephalopathy. Rewarming was obtained in the following 6–12 hours (0.5°C/h) after cooling. Heart rates were the same between the two groups; there was statistically significant difference at the beginning of hypothermia and during rewarming. Three babies in the DH group and 2 in the MH group showed HR < 80 bpm and QTc > 520 ms. Infant submitted to deep hypothermia had not bradycardia or Qtc elongation before cooling and after rewarming. Blood pressure was significantly lower in DH compared to MH during the cooling, and peculiar was the hypotension during rewarming in DH group. Conclusion. The deeper hypothermia is a safe and feasible, only if it is performed by a well-trained team. DH should only be associated with a clinical trial and prospective randomized trials to validate its use.
doi:10.1155/2013/140213
PMCID: PMC3649319  PMID: 23691350
24.  Effects of combination therapy using hypothermia and erythropoietin in a rat model of neonatal hypoxia–ischemia 
Pediatric research  2012;73(1):12-17.
BACKGROUND
Hypoxic–ischemic (HI) injury to the developing brain remains a major cause of morbidity. Hypothermia is effective but does not provide complete neuroprotection, prompting a search for adjunctive therapies. Erythropoietin (Epo) has been shown to be beneficial in several models of neonatal HI. This study examines combination hypothermia and treatment with erythropoietin in neonatal rat HI.
METHODS
Rats at postnatal day 7 were subjected to HI (Vannucci model) and randomized into four groups: no treatment, hypothermia alone, Epo alone, or hypothermia and Epo. Epo (1,000 U/kg) was administered in three doses: immediately following HI, and 24 h and 1 wk later. Hypothermia consisted of whole-body cooling for 8 h. At 2 and 6 wk following HI, sensorimotor function was assessed via cylinder-rearing test and brain damage by injury scoring. Sham-treated animals not subjected to HI were also studied.
RESULTS
Differences between experimental groups, except for Epo treatment on histopathological outcome in males, were not statistically significant, and combined therapy had no adverse effects.
CONCLUSION
No significant benefit was observed from treatment with either hypothermia or combination therapy. Future studies may require older animals, a wider range of functional assays, and postinsult assessment of injury severity to identify only moderately damaged animals for targeted therapy.
doi:10.1038/pr.2012.138
PMCID: PMC3540182  PMID: 23085817
25.  Neurological outcomes at 18 months of age after moderate hypothermia for perinatal hypoxic ischaemic encephalopathy: synthesis and meta-analysis of trial data 
Objective To determine whether moderate hypothermia after hypoxic-ischaemic encephalopathy in neonates improves survival and neurological outcome at 18 months of age.
Design A meta-analysis was performed using a fixed effect model. Risk ratios, risk difference, and number needed to treat, plus 95% confidence intervals, were measured.
Data sources Studies were identified from the Cochrane central register of controlled trials, the Oxford database of perinatal trials, PubMed, previous reviews, and abstracts.
Review methods Reports that compared whole body cooling or selective head cooling with normal care in neonates with hypoxic-ischaemic encephalopathy and that included data on death or disability and on specific neurological outcomes of interest to patients and clinicians were selected.
Results We found three trials, encompassing 767 infants, that included information on death and major neurodevelopmental disability after at least 18 months’ follow-up. We also identified seven other trials with mortality information but no appropriate neurodevelopmental data. Therapeutic hypothermia significantly reduced the combined rate of death and severe disability in the three trials with 18 month outcomes (risk ratio 0.81, 95% confidence interval 0.71 to 0.93, P=0.002; risk difference −0.11, 95% CI −0.18 to −0.04), with a number needed to treat of nine (95% CI 5 to 25). Hypothermia increased survival with normal neurological function (risk ratio 1.53, 95% CI 1.22 to 1.93, P<0.001; risk difference 0.12, 95% CI 0.06 to 0.18), with a number needed to treat of eight (95% CI 5 to 17), and in survivors reduced the rates of severe disability (P=0.006), cerebral palsy (P=0.004), and mental and the psychomotor developmental index of less than 70 (P=0.01 and P=0.02, respectively). No significant interaction between severity of encephalopathy and treatment effect was detected. Mortality was significantly reduced when we assessed all 10 trials (1320 infants; relative risk 0.78, 95% CI 0.66 to 0.93, P=0.005; risk difference −0.07, 95% CI −0.12 to −0.02), with a number needed to treat of 14 (95% CI 8 to 47).
Conclusions In infants with hypoxic-ischaemic encephalopathy, moderate hypothermia is associated with a consistent reduction in death and neurological impairment at 18 months.
doi:10.1136/bmj.c363
PMCID: PMC2819259  PMID: 20144981

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