Cerebral monitoring of the term infant.

Continuously monitoring brain ftinction at the bedside in the NICU for term infants at risk of brain injury has become part of routine clinical practice in many countries. These monitors offer invaluable information about the sick infant's neurologic status by providing real-time measurements of the brain's electrical activity and identifring or confirming seizure activity. With the increasing availability of bedside electroencephalogram technology, it is essential for neonatal intensive care nursing staff to understand the rationale for its use, as well as the fundamentals of application and interpretation of this new technology.

Accuracy of bedside electroencephalographic monitoring in comparison with simultaneous continuous conventional electroencephalography for seizure detection in term infants.

OBJECTIVE: Our goals were to compare (1) single-channel amplitude-integrated electroencephalography alone, (2) 2-channel amplitude-integrated electroencephalography alone, and (3) amplitude-integrated electroencephalography plus 2-channel electroencephalography with simultaneous continuous conventional electroencephalography for seizure detection in term infants to check the accuracy of limited channels and compare the different modalities of bedside electroencephalography monitoring. METHODS: Infants referred to a tertiary center with clinical seizures underwent simultaneous continuous conventional electroencephalography and 2-channel (C3-P3 and C4-P4) bedside monitoring. Off-line analysis of the continuous conventional electroencephalographic results was performed independently by 2 neurologists. Two experienced neonatal readers reviewed results obtained with amplitude-integrated electroencephalography and 2-channel electroencephalography combined and single-channel and 2-channel amplitude-integrated electroencephalography. All readings were performed independently and then compared. RESULTS: Twenty-one term newborns were monitored. Seizures were detected in 7 patients who had up to 12 electrical seizures, with 1 infant in status epilepticus. Seizures were identified correctly in 6 of 7 patients with amplitude-integrated electroencephalography plus 2-channel electroencephalography. The missed infant had an isolated 12-second seizure. With amplitude-integrated electroencephalography plus 2-channel electroencephalography, 31 of 41 non-status epilepticus seizures were correctly identified (sensitivity, 76%; specificity, 78%; positive predictive value, 78%; negative predictive value, 78%), with a substantial level of interrater agreement. The seizures missed were predominantly slow sharp waves of occipital origin from a single patient (7 of 10 seizures). Nine false-positive results were obtained in 351 hours of recording (1 false-positive result per 39 hours). These were thought to be related to muscle, electrode, and patting artifacts. Use of amplitude-integrated electroencephalography alone (1 or 2 channel) provided low sensitivity (27%-56%) and low interobserver agreement. CONCLUSIONS: Limited-channel bedside electroencephalography combining amplitude-integrated electroencephalography with 2-channel electroencephalography, interpreted by experienced neonatal readers, detected the majority of electrical seizures in at-risk newborn infants.

Single versus bihemispheric amplitude-integrated electroencephalography in relation to cerebral injury and outcome in the term encephalopathic infant.

BACKGROUND: The demand for early diagnosis and prognostication of cerebral injury in the encephalopathic term infant is increasing to facilitate appropriate management. The single-channel amplitude-integrated electroencephalogram (S-aEEG) has been shown to have predictive utility for the severely encephalopathic infant. New bedside aEEG devices with more channels are entering the neonatal environment. Little data are available to compare the utility of two channels (B-aEEG) with that of an S-aEEG recording. AIM: To compare the utility of the S-aEEG and the B-aEEG in the prediction of cerebral injury, as determined by magnetic resonance imaging (MRI), and neurodevelopmental outcome in the term encephalopathic infant. METHODS: Term encephalopathic infants, with or without seizures, admitted to a level III NICU were included in this study. These infants had simultaneous S-aEEG and B-aEEG recordings. MRI was undertaken during the clinical course and classified as to the extent of cerebral injury. Neurological outcome was assessed at 2 years of age. RESULTS: Twenty-eight encephalopathic term infants were included in the study. There was high level of agreement between both brain monitors (Kappa = 0.68, P < 0.001), but there was disagreement in the classification in four cases where the S-aEEG was normal when the B-aEEG was severely abnormal (McNemar's test P = 0.046). Of note in these four cases, all had a severely abnormal MRI and poor neurodevelopmental outcome at 2 years. CONCLUSION: Amplitude measurements by the B-aEEG appear more sensitive in detecting cerebral injury in comparison with the S-aEEG, particularly in the setting of unilateral injury.

Use of 2-channel bedside electroencephalogram monitoring in term-born encephalopathic infants related to cerebral injury defined by magnetic resonance imaging.

OBJECTIVE: Single-channel amplitude-integrated electroencephalography has been shown to be predictive of neurodevelopmental outcome in term infants with hypoxic-ischemic encephalopathy. We describe the relationship of quantifiable electroencephalogram (EEG) measures, obtained using a 2-channel digital bedside EEG monitor from term newborn infants with encephalopathy and/or seizures, to cerebral injury defined qualitatively by MRI. METHODS: Median values of minimum, mean, and maximum EEG amplitude were obtained from term-born encephalopathic infants during a 2-hour seizure-free period obtained within 72 hours of admission. Infants underwent MRI with images qualitatively scored for abnormalities of cortex, white matter, deep nuclear gray matter, and posterior limb of the internal capsule. Eighty-six infants had EEG measures related to qualitative MRI outcomes. RESULTS: The most common diagnosis was hypoxic ischemic encephalopathy (n = 40). For all infants there was a negative relationship between EEG amplitude measures and MRI abnormality scores assessed on a scale from 4 to 15, with a higher score indicating more abnormalities. This relationship was strongest for the minimum amplitude measures in both hemispheres; that is, for every unit increase in score there was a mean drop of 0.41 microV for the left cerebral hemisphere, with 35% of variance explained. This relationship persisted on sub-group analyses for infants with hypoxic-ischemic encephalopathy, infants with other diagnoses and infants monitored after the first 24 hours of life. Using an MRI abnormality score cutoff of 8 or worse for cerebral injury in infants with hypoxic-ischemic encephalopathy, a minimum amplitude of 4 microV showed a higher specificity (80%: left hemisphere), whereas a minimum amplitude of 6 muV showed a higher sensitivity (92%: left hemisphere). CONCLUSIONS: Bedside EEG measures in term-born encephalopathic infants are related to the severity of cerebral injury as defined by qualitative MRI. A minimum amplitude of <4 microV appears useful in predicting outcome.