Limitations of Conventional Magnetic Resonance Imaging as a Predictor of Death or Disability Following Neonatal Hypoxic-Ischemic Encephalopathy in the Late Hypothermia Trial.

OBJECTIVE: To investigate if magnetic resonance imaging (MRI) is an accurate predictor for death or moderate-severe disability at 18-22 months of age among infants with neonatal encephalopathy in a trial of cooling initiated at 6-24 hours. STUDY DESIGN: Subgroup analysis of infants ≥36 weeks of gestation with moderate-severe neonatal encephalopathy randomized at 6-24 postnatal hours to hypothermia or usual care in a multicenter trial of late hypothermia. MRI scans were performed per each center's practice and interpreted by 2 central readers using the Eunice Kennedy Shriver National Institute of Child Health and Human Development injury score (6 levels, normal to hemispheric devastation). Neurodevelopmental outcomes were assessed at 18-22 months of age. RESULTS: Of 168 enrollees, 128 had an interpretable MRI and were seen in follow-up (n = 119) or died (n = 9). MRI findings were predominantly acute injury and did not differ by cooling treatment. At 18-22 months, death or severe disability occurred in 20.3%. No infant had moderate disability. Agreement between central readers was moderate (weighted kappa 0.56, 95% CI 0.45-0.67). The adjusted odds of death or severe disability increased 3.7-fold (95% CI 1.8-7.9) for each increment of injury score. The area under the curve for severe MRI patterns to predict death or severe disability was 0.77 and the positive and negative predictive values were 36% and 100%, respectively. CONCLUSIONS: MRI injury scores were associated with neurodevelopmental outcome at 18-22 months among infants in the Late Hypothermia Trial. However, the results suggest caution when using qualitative interpretations of MRI images to provide prognostic information to families following perinatal hypoxia-ischemia. TRIAL REGISTRATION: Clinicaltrials.gov: NCT00614744.

Perinatal asphyxia with hyperoxemia within the first hour of life is associated with moderate to severe hypoxic-ischemic encephalopathy.

OBJECTIVE: To determine whether early hyperoxemia in neonates with severe perinatal acidemia is associated with the development of hypoxic-ischemic encephalopathy (HIE). STUDY DESIGN: We identified 120 infants at ≥ 36 weeks gestational age with perinatal acidosis born at Parkland Hospital who qualified for a screening neurologic exam for cooling therapy. Based on a PaO2 measurement during the first hour of life, the cohort was divided into infants with hyperoxemia (PaO2 >100 mmHg) and those without hyperoxemia (PaO2 ≤ 100 mmHg). The rate of moderate-severe encephalopathy was compared between the groups using χ(2) analysis, as well as multiple logistic regression, taking into account baseline characteristics and confounding variables. RESULTS: Thirty-six infants (30%) had an initial PaO2 >100 mmHg. Infants with and without hyperoxemia had similar baseline maternal and infant characteristics. Infants with hyperoxemia had a higher incidence of HIE than those without hyperoxemia (58% vs 27%; P = .003). Admission hyperoxemia was associated with a higher risk of HIE (OR, 4; 95% CI, 1.4-10.5; adjusted P = .01). Among the neonates with moderate-severe HIE during the first 6 hours of life, those with hyperoxemia had a higher incidence of abnormal brain magnetic resonance imaging results, consistent with hypoxic ischemic injury, compared with those without hyperoxemia (79% vs 33%; P = .015). CONCLUSION: In neonates with perinatal acidemia, admission hyperoxemia is associated with a higher incidence of HIE. Among neonates with HIE, admission hyperoxemia is associated with abnormal brain magnetic resonance imaging findings. The judicious use of oxygen during and after resuscitation is warranted.

Perinatal acidosis and hypoxic-ischemic encephalopathy in preterm infants of 33 to 35 weeks' gestation.

OBJECTIVES: To determine the frequency of hypoxic-ischemic encephalopathy (HIE) in preterm infants of 33 to 35 weeks' gestational age on the basis of physiological screening for perinatal acidosis and neurological assessment of encephalopathy and to correlate neurodevelopmental outcomes with brain magnetic resonance imaging findings. STUDY DESIGN: This retrospective cohort study included all inborn infants of 33 to 35 weeks' gestation admitted to the neonatal intensive care unit at Parkland Memorial Hospital with perinatal acidosis from October 2005 to September 2008. Their medical records were reviewed, and pertinent data were recorded. RESULTS: Of 1305 newborns, 2.5% (n=33) had perinatal acidosis, and 27% (n=9) of these had HIE (2, mild; 4, moderate; 3, severe). Persistence of metabolic acidosis on the first arterial blood gas obtained in the first hour of age was significantly associated with HIE (P<.005). Magnetic resonance imaging results were abnormal in 3 of 4 infants with moderate HIE and in both survivors with severe HIE. Death or disability occurred in no infants with mild or moderate HIE, but in all infants with severe HIE. CONCLUSION: Screening criteria for HIE that use biochemical and neurological assessments as performed in term newborns can be applied to preterm infants of 33 to 35 weeks' gestation.