Cerebral regional oxygen saturation trends in infants with hypoxic-ischemic encephalopathy.

BACKGROUND: Neurological outcomes in neonatal hypoxic-ischemic encephalopathy (HIE) continue to be sub-optimal despite therapeutic hypothermia (TH). Cerebral near-infrared spectroscopy provides real-time regional oxygen saturation (CrSO2) that may be a marker of adverse MRI findings and neurodevelopmental outcomes. AIM: The aim of this study was to examine the value of CrSO2 monitoring in infants with HIE undergoing TH. STUDY DESIGN AND SUBJECTS: In this prospective study, CrSO2 was continuously recorded in 21 infants with HIE admitted for TH. OUTCOME MEASURES: Brain MRI signal abnormalities at 2weeks were scored in individual brain region and classified as none/mild, moderate and severe. 13 infants completed Bayley Scales of Infant Development (BSID) testing at 18-24months. RESULTS: Between 24 and 36h of life, there was a significant increase in odds of having moderate-severe brain MRI abnormalities with higher absolute CrSO2 values. Per 10% increase in absolute CrSO2, the odds ratio for moderate-severe brain MRI abnormalities was greatest at 30h (OR 3.78; confidence intervals (CI): 1.23-11.6, p=0.011). CrSO2 increased more rapidly in infants with greater injury seen on MRI (0.20/h for MRI scores 0/1, by 0.48/h for MRI score 2, and by 0.68/h for MRI score 3, p=0.05). At 30h, absolute CrSO2 correlated significantly with abnormal MRI findings in basal ganglia (92% vs. 78%, p=0.001), white matter (88% vs. 76%, p=0.01), posterior limb of internal capsule (92% vs. 78%, p=0.001), and brain stem (94% vs. 80%, p=0.03) but not with cortical injury (86% vs. 80%, p=0.17). Higher CrSO2 beyond 24h correlated with greater odds of worse BSID scores. CONCLUSIONS: Increasing CrSO2 is associated with moderate-severe brain injury as assessed by MRI. Higher absolute CrSO2 values during TH correlates with subcortical injury on MRI and poor neurodevelopmental outcomes in infants with HIE undergoing TH. CrSO2 can inform providers seeking early identification of patients at risk of worse injury who may benefit from further intervention.

Prediction of Neonatal Seizures in Hypoxic-Ischemic Encephalopathy Using Electroencephalograph Power Analyses.

BACKGROUND: The severity of the initial encephalopathy in neonatal hypoxic-ischemic encephalopathy correlates with seizure burden. Early electroencephalograph (EEG) background activity reflects the severity of encephalopathy. Thus, we hypothesized that early EEG background would be predictive of subsequent seizures in neonatal hypoxic-ischemic encephalopathy. METHODS: This study included infants undergoing therapeutic hypothermia at St. Louis Children's Hospital between January 2009 and April 2013. Two pediatric epilepsy specialists independently characterized EEG background qualitatively using amplitude-integrated EEG trends. Total EEG power in the 1-20 Hz frequency band was calculated for quantitative EEG background assessment. Seizures were identified on conventional full montage EEG. Statistical analysis was performed using logistic regression. RESULTS: Seventy-eight of the 93 eligible infants had artifact-free EEG data; 23 of 78 infants (29%) developed seizures, and of these, 11 developed status epilepticus. The best predictors of subsequent seizures during the first hour of EEG recording were a flat tracing pattern on amplitude-integrated EEG (sensitivity 26%, specificity 98%, likelihood ratio 13, positive predictive value 85%) and the total EEG power less than 10 µV2 (sensitivity 52%, specificity 98%, likelihood ratio 30, positive predictive value 92%). CONCLUSIONS: Early EEG biomarkers predict subsequent seizures in infants with hypoxic-ischemic encephalopathy. Compared with the qualitative amplitude-integrated EEG background, total EEG power improves our ability to identify high-risk infants from the first hour of EEG recording. Infants with a total EEG power of less than 10 µV2 have a 90% risk of subsequent seizures. Quantitative EEG measures could stratify cohorts while evaluating novel neuroprotective strategies in neonatal hypoxic-ischemic encephalopathy.