Seetha Shankaran

Elevated Temperature After Hypoxic-Ischemic Encephalopathy: Risk Factor for Adverse Outcomes

OBJECTIVE. The goal was to determine whether the risk of death or moderate/severe disability in term infants with hypoxic-ischemic encephalopathy increases with relatively high esophageal or skin temperature occurring between 6 and 78 hours after birth. METHODS. This was an observational secondary study within the National Institute of Child Health and Human Development Neonatal Research Network randomized trial comparing whole-body cooling and usual care (control) for term infants with hypoxic-ischemic encephalopathy. Esophageal and skin temperatures were recorded serially for 72 hours. Each infants temperatures for each site were rank ordered. The high temperature was defined for each infant as the mean of all temperature measurements in the upper quartile. The low temperature was similarly defined as the mean of the lower quartile. Outcomes were related to temperatures in 3 logistic regression analyses for the high, median, and low temperatures at each temperature site for each group, with adjustment for the level of encephalopathy, gender, gestational age, and race. RESULTS. In control infants, the mean esophageal temperature was 37.2 ± 0.7°C over the 72-hour period, and 63%, 22%, and 8% of all temperatures were >37°C, >37.5°C, and >38°C, respectively. The mean skin temperature was 36.5 ± 0.8°C, and 12%, 5%, and 2% of all temperatures were >37°C, >37.5°C, and >38°C, respectively. The odds of death or disability were increased 3.6–4 fold for each 1°C increase in the highest quartile of skin or esophageal temperatures. There were no associations between temperatures and outcomes in the cooling-treated group. CONCLUSIONS. Relatively high temperatures during usual care after hypoxia-ischemia were associated with increased risk of adverse outcomes. The results may reflect underlying brain injury and/or adverse effects of temperature on outcomes.

Outcomes of Safety and Effectiveness in a Multicenter Randomized, Controlled Trial of Whole-Body Hypothermia for Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND. Whole-body hypothermia reduced the frequency of death or moderate/severe disabilities in neonates with hypoxic-ischemic encephalopathy in a randomized, controlled multicenter trial. OBJECTIVE. Our goal was to evaluate outcomes of safety and effectiveness of hypothermia in infants up to 18 to 22 months of age. DESIGN/METHODS. A priori outcomes were evaluated between hypothermia (n = 102) and control (n = 106) groups. RESULTS. Encephalopathy attributable to causes other than hypoxia-ischemia at birth was not noted. Inotropic support (hypothermia, 59% of infants; control, 56% of infants) was similar during the 72-hour study intervention period in both groups. Need for blood transfusions (hypothermia, 24%; control, 24%), platelet transfusions (hypothermia, 20%; control, 12%), and volume expanders (hypothermia, 54%; control, 49%) was similar in the 2 groups. Among infants with persistent pulmonary hypertension (hypothermia, 25%; control, 22%), nitric-oxide use (hypothermia, 68%; control, 57%) and placement on extracorporeal membrane oxygenation (hypothermia, 4%; control, 9%) was similar between the 2 groups. Non–central nervous system organ dysfunctions occurred with similar frequency in the hypothermia (74%) and control (73%) groups. Rehospitalization occurred among 27% of the infants in the hypothermia group and 42% of infants in the control group. At 18 months, the hypothermia group had 24 deaths, 19 severe disabilities, and 2 moderate disabilities, whereas the control group had 38 deaths, 25 severe disabilities, and 1 moderate disability. Growth parameters were similar between survivors. No adverse outcomes were noted among infants receiving hypothermia with transient reduction of temperature below a target of 33.5°C at initiation of cooling. There was a trend in reduction of frequency of all outcomes in the hypothermia group compared with the control group in both moderate and severe encephalopathy categories. CONCLUSIONS. Although not powered to test these secondary outcomes, whole-body hypothermia in infants with encephalopathy was safe and was associated with a consistent trend for decreasing frequency of each of the components of disability.

Outcome of Term Infants Using Apgar Scores at 10 Minutes Following Hypoxic-Ischemic Encephalopathy

OBJECTIVE: The objective of this study was to determine whether Apgar scores at 10 minutes are associated with death or disability in early childhood after perinatal hypoxic-ischemic encephalopathy. METHODS: This was a secondary analysis of infants who were enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network hypothermia trial. Infants who were born at ≥36 weeks’ gestation and had clinical and/or biochemical abnormalities at birth and encephalopathy at <6 hours were studied. Logistic regression and classification and regression-tree analysis were used to determine associations between Apgar scores at 10 minutes and neurodevelopmental outcome, adjusting for covariates. Death or disability (moderate or severe) at 18 to 22 months of age was the measured outcome. RESULTS: Twenty of 208 infants were excluded (missing data). More than 90% of the infants had Apgar scores of 0 to 2 at 1 minute, and Apgar scores at 5 and 10 minutes shifted to progressively higher values; at 10 minutes, 27% of infants had Apgar scores of 0 to 2. After adjustment, each point decrease in Apgar score at 10 minutes was associated with a 45% increase in the odds of death or disability. Death or disability occurred in 76%, 82%, and 80% of infants with 10-minute Apgar scores of 0, 1, and 2, respectively. Classification and regression-tree analysis indicated that Apgar scores at 10 minutes were discriminators of outcome. CONCLUSIONS: Apgar scores at 10 minutes provide useful prognostic data before other evaluations are available for infants with hypoxic-ischemic encephalopathy. Death or moderate/severe disability is common but not uniform with Apgar scores of <3; caution is needed before adopting a specific time interval to guide duration of resuscitation.

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.

Outcomes of extremely low birth weight infants with bronchopulmonary dysplasia: Impact of the physiologic definition

AIMSnWe compared neurodevelopmental outcomes of extremely low birth weight (ELBW) infants with and without bronchopulmonary dysplasia (BPD), using the physiologic definition.nnnSTUDY DESIGNnELBW (birth weights<1000 g) infants admitted to the Neonatal Research Network centers and hospitalized at 36 weeks postmenstrual age (n=1189) were classified using the physiologic definition of BPD. Infants underwent Bayley III assessment at 18-22 months corrected age. Multivariable logistic regression was used to determine the association between physiologic BPD and cognitive impairment (score<70).nnnRESULTSnBPD by the physiologic definition was diagnosed in 603 (52%) infants, 537 of whom were mechanically ventilated or on FiO(2)>30% and 66 who failed the room air challenge. Infants on room air (n=505) and those who passed the room air challenge (n=51) were classified as no BPD (n=556). At follow up, infants with BPD had significantly lower mean weight and head circumference. Moderate to severe cerebral palsy (7 vs. 2.1%) and spastic diplegia (7.8 vs. 4.1%) and quadriplegia (3.9 vs. 0.9%) phenotypes as well as cognitive (12.8 vs. 4.6%) and language scores<70 (24.2 vs. 12.3%) were significantly more frequent in those with BPD compared to those without BPD. BPD was independently associated (adjusted OR 2.4; 95% CI 1.40-4.13) with cognitive impairment.nnnCONCLUSIONSnRates of adverse neurodevelopmental outcomes in early childhood were significantly higher in those with BPD. BPD by the physiologic definition was independently associated with cognitive impairment using Bayley Scales III. These findings have implications for targeted post-discharge surveillance and early intervention.

Predicting outcomes of neonates diagnosed with hypoxemic-ischemic encephalopathy

OBJECTIVE. The goals were to identify predictor variables and to develop scoring systems and classification trees to predict death/disability or death in infants with hypoxic-ischemic encephalopathy. METHODS. Secondary analysis of data from the multicenter, randomized, controlled, National Institute of Child Health and Human Development Neonatal Research Network trial of hypothermia in hypoxic-ischemic encephalopathy was performed. Data for 205 neonates diagnosed as having hypoxic-ischemic encephalopathy were studied. Logistic regression analysis was performed by using clinical and laboratory variables available within 6 hours of birth, with death or moderate/severe disability at 18 to 22 months or death as the outcomes. By using the identified variables and odds ratios, scoring systems to predict death/disability or death were developed, weighting each predictor in proportion to its odds ratio. In addition, classification and regression tree analysis was performed, with recursive partitioning and automatic selection of optimal cutoff points for variables. Correct classification rates for the scoring systems, classification and regression tree models, and early neurologic examination were compared. RESULTS. Correct classification rates were 78% for death/disability and 71% for death with the scoring systems, 80% and 77%, respectively, with the classification and regression tree models, and 67% and 73% with severe encephalopathy in early neurologic examination. Correct classification rates were similar in the hypothermia and control groups. CONCLUSIONS. Among neonates diagnosed as having hypoxic-ischemic encephalopathy, the classification and regression tree model, but not the scoring system, was superior to early neurologic examination in predicting death/disability. The 3 models were comparable in predicting death. Only a few components of the early neurologic examination were associated with poor outcomes. These scoring systems and classification trees, if validated, may help in assessments of prognosis and may prove useful for risk-stratification of infants with hypoxic-ischemic encephalopathy for clinical trials.

Cumulative Index of Exposure to Hypocarbia and Hyperoxia as Risk Factors for Periventricular Leukomalacia in Low Birth Weight Infants

BACKGROUND. Hypocarbia and hyperoxia are risk factors for periventricular leukomalacia in low birth weight infants. The association of a cumulative index of exposure to hypocarbia and hyperoxia and periventricular leukomalacia has not been evaluated. OBJECTIVE. Our goal was to examine the relationship between cumulative index of exposure to hypocarbia and hyperoxia and periventricular leukomalacia during the first 7 days of life in low birth weight infants. METHODS. Blood gas results were recorded in 6-hour intervals among low birth weight infants in a prospective data registry. Cumulative index of exposure to hypocarbia was calculated as the difference between arterial carbon dioxide level and 35 mmHg multiplied by the time interval in hours for each 6-hour block in a 24-hour day for the first 7 days of life. Cumulative index of exposure to hyperoxia was calculated in the same manner for arterial oxygen level >80 mm Hg. The relationship between exposure to hypocarbia, hyperoxia, and periventricular leukomalacia was examined in 778 infants with blood gas and cranial sonography data. RESULTS. Twenty-one infants had periventricular leukomalacia. Hypocarbia occurred in 489 infants and hyperoxia in 502 infants. Infants with periventricular leukomalacia were more likely to have a lower gestational age and to require delivery room resuscitation than those without periventricular leukomalacia. More infants in the highest quartile of exposure to hypocarbia had periventricular leukomalacia compared to those with no hypocarbia. Risk of periventricular leukomalacia was increased in infants with the highest quartile of exposure to hypocarbia after adjusting for maternal and neonatal variables, none to be associated with periventricular leukomalacia. Cumulative index exposure to hyperoxia was not related to periventricular leukomalacia. CONCLUSIONS. Cumulative exposure to hypocarbia and not hyperoxia was independently related to risk of periventricular leukomalacia in low birth weight infants.

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:

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.

Hypocarbia and Adverse Outcome in Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVEnTo evaluate the association between early hypocarbia and 18- to 22-month outcome among neonates with hypoxic-ischemic encephalopathy.nnnSTUDY DESIGNnData from the National Institute of Child Health and Human Development Neonatal Research Network randomized, controlled trial of whole-body hypothermia for neonatal hypoxic-ischemic encephalopathy were used for this secondary observational study. Infants (n = 204) had multiple blood gases recorded from birth to 12 hours of study intervention (hypothermia versus intensive care alone). The relationship between hypocarbia and outcome (death/disability at 18 to 22 months) was evaluated by unadjusted and adjusted analyses examining minimum PCO(2) and cumulative exposure to PCO(2) <35 mm Hg. The relationship between cumulative PCO(2) <35 mm Hg (calculated as the difference between 35 mm Hg and the sampled PCO(2) multiplied by the duration of time spent <35 mm Hg) 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), and time to spontaneous respiration and ventilator days; results were expressed as odds ratios and 95% confidence intervals. Alternative models of CO(2) concentration were explored to account for fluctuations in CO(2).nnnRESULTSnBoth minimum PCO(2) and cumulative PCO(2) <35 mm Hg were associated with poor outcome (P < .05). Moreover, death/disability increased with greater cumulative exposure to PCO(2) <35 mm Hg.nnnCONCLUSIONSnHypocarbia is associated with poor outcome after hypoxic-ischemic encephalopathy.

Predictive Value of an Early Amplitude Integrated Electroencephalogram and Neurologic Examination

OBJECTIVE: To examine the predictive validity of the amplitude integrated electroencephalogram (aEEG) and stage of encephalopathy among infants with hypoxic-ischemic encephalopathy (HIE) eligible for therapeutic whole-body hypothermia. DESIGN: Neonates were eligible for this prospective study if moderate or severe HIE occurred at <6 hours and an aEEG was obtained at <9 hours of age. The primary outcome was death or moderate/severe disability at 18 months. RESULTS: There were 108 infants (71 with moderate HIE and 37 with severe HIE) enrolled in the study. aEEG findings were categorized as normal, with continuous normal voltage (n = 12) or discontinuous normal voltage (n = 12), or abnormal, with burst suppression (n = 22), continuous low voltage (n = 26), or flat tracing (n = 36). At 18 months, 53 infants (49%) experienced death or disability. Severe HIE and an abnormal aEEG were related to the primary outcome with univariate analysis, whereas severe HIE alone was predictive of outcome with multivariate analysis. Addition of aEEG pattern to HIE stage did not add to the predictive value of the model; the area under the curve changed from 0.72 to 0.75 (P = .19). CONCLUSIONS: The aEEG background pattern did not significantly enhance the value of the stage of encephalopathy at study entry in predicting death and disability among infants with HIE.