Comparison between tape-recorded and amplitude-integrated EEG monitoring in sick newborn infants

In 15 ill newborn infants a comparison between long-term multichannel and single-channel recordings of simultaneously tape-recorded (Medilog system) and amplitude-integrated EEG (Cerebral Function Monitor) was made. There was good agreement between the main type of background activity diagnosed with the tape-recorded and the amplitude-integrated EEG for all recordings. Two infants had repetitive subclinical and subtle seizure activity, lasting for several hours, which was detected by both techniques. Short, single seizures were diagnosed in the recordings of nine infants. When a single electrographic seizure appeared in an otherwise stable recording, it was identified by both the tape-recorded and the amplitude-integrated EEG. Very short (5-30 s) seizure patterns, which were diagnosed with the tape-recorded EEG, were not identified in the cerebral function monitor recordings. In the single-channel recordings of both the EEG and the cerebral function monitor there were, on some occasions, difficulties in distinguishing single seizures from interference due to external artefacts. In the multichannel recordings the diagnosis of seizure patterns was facilitated by comparison with the other channels. Both the Medilog EEG and the cerebral function monitor are feasible techniques for following cerebral electrical activity in sick neonates, although neither technique is specifically constructed for this purpose. For clinical use in the neonatal intensive care unit the advantage with the cerebral function monitor is the immediately available recording. The tape-recorded EEG offers possibilities of more channels and a higher reliability when diagnosing short subclinical seizures, however, only after offline analysis

Cerebral O2 supply thresholds for the preservation of electrocortical brain activity during hypotension in near-term-born lambs.

Item does not contain fulltextThe fetal brain develops rapidly during the last trimester of pregnancy. Therefore, the brain of infants who are born preterm is vulnerable to changes in oxygen and nutrient supply in the neonatal period. The objective was to determine the effect of gestational age (GA) on the cerebral O2 supply threshold level for preservation of brain function during hypotension in near-term-born lambs. Lambs were delivered at 141 or 127 d of gestation. Hypotension was induced by stepwise withdrawal of blood. Mean arterial blood pressure (MABP) baseline levels were 63.2 (6.4) in 141-d and 54.4 (15.5) mm Hg in 127-d lambs. The MABP threshold below which MABP and blood flow in the left carotid artery were linearly related was 36.1 (13.1) mm Hg in 141-d lambs. In 127-d lambs, MABP and blood flow in the left carotid artery were linearly related over the whole range of recorded MABP values. Electrocortical brain activity (ECBA) was used as a measure of brain function. Thresholds of MABP for maintenance of ECBA were reached at, respectively, 31.6% (4.9%) of baseline in 141-d and 61.9% (13.0%) of baseline MABP in 127-d lambs. However, thresholds of cerebral O2 supply for maintenance of ECBA were similar in both GA groups. We conclude that thresholds of cerebral O2 supply for maintenance of brain cell function are independent of GA but are reached at higher MABP levels in 127-d than in 141-d lambs and therefore places the sick preterm infant easily at risk for ischemic cerebral injury