Desflurane results in higher cerebral blood flow than sevoflurane or isoflurane at hypocapnia in pigs.

Background: In clinical neuroanaesthesia, the increase in cerebral blood flow (CBF) and intracranial pressure caused by the cerebral vasodilative effects of an inhalational anaesthetic agent is counteracted by the cerebral vasoconstriction induced by hypocapnia. Desflurane and sevoflurane may have advantages over the more traditionally used isoflurane in neuroanaesthesia but their dose-dependent vasodilative effects at hypocapnia have not been compared in the same model using truly equipotent minimal alveolar concentrations (MACs). Method: Desflurane, sevoflurane and isoflurane were administered in a randomized order to six pigs at 0.5 and 1.0 MAC. The intra-arterial xenon clearance technique was used to calculate CBF. Blood pressure was invasively monitored. Cerebral and systemic physiological variables were recorded first at normocapnia (PaCO2 5.6 kPa) and then at hypocapnia (PaCO2 3.5 kPa). Electroencephalographic (EEG) activity was continuously recorded. Results: None of the three agents abolished cerebrovascular reactivity to hyperventilation, and at 0.5 MAC all had similar effects on CBF at hypocapnia. Desflurane at 1.0 MAC was associated with 16% higher CBF (P = 0.027) at hypocapnia than isoflurane, and with 24% higher CBF (P = 0.020) than sevoflurane. There was no seizure activity in the EEG. Conclusion: More cerebral vasodilation at hypocapnia with high doses of desflurane than with sevoflurane or isoflurane indicates that desflurane might be less suitable for neuroanaesthesia than sevoflurane and isoflurane

Premedication for intubation with morphine causes prolonged depression of electrocortical background activity in preterm infants.

Background:Sedative and analgesic medications are used in critically ill newborns, but little is known about their effects on electrocortical activity in preterm infants. We hypothesized that morphine might induce prolonged neurodepression, independent of blood pressure, compared with rapid sequence induction/intubation (RSI).Methods:Of 34 infants enrolled into a randomized controlled trial (RCT) comparing RSI (including thiopental 2-3 mg/kg and remifentantil 1 microg/kg) with morphine (0.3 mg/kg) as premedication for intubation, 28 infants (n=14+14; median gestational age 26.1 weeks and postnatal age 138 h) had continuous two-channel amplitude-integrated electroencephalogram (aEEG/EEG) and blood pressure monitoring during 24 h after the intubation. Thirteen infants not receiving any additional medication constituted the primary study group. Visual and quantitative analyses of aEEG/EEG and blood pressure were performed in 3-h epochs.Results:RSI was associated with aEEG/EEG depression lasting less than 3 h. Morphine premedication resulted in aEEG/EEG depression with more discontinuous background and less developed cyclicity for 24 h, and during the first 9 h interburst intervals were significantly increased compared to RSI. The difference was not related to blood pressure.Conclusion:Premedication with morphine is associated with prolonged aEEG/EEG depression independent of blood pressure changes, and may not be optimal for short procedures.Pediatric Research (2012); doi:10.1038/pr.2012.153

Auditory event-related potentials at preschool age in children born very preterm.

To assess auditory event-related potentials at preschool age in children born very preterm (VP, 27.4±1.9 gestational weeks, n=70) with a high risk of cognitive dysfunction

Interobserver agreement for neonatal seizure detection using multichannel EEG

Objective To determine the interobserver agreement (IOA) of neonatal seizure detection using the gold standard of conventional, multichannel EEG. Methods A cohort of full-term neonates at risk of acute encephalopathy was included in this prospective study. The EEG recordings of these neonates were independently reviewed for seizures by three international experts. The IOA was estimated using statistical measures including Fleiss' kappa and percentage agreement assessed over seizure events (event basis) and seizure duration (temporal basis). Results A total of 4066 h of EEG recordings from 70 neonates were reviewed with an average of 2555 seizures detected. The IOA was high with temporal assessment resulting in a kappa of 0.827 (95% CI: 0.769–0.865; n = 70). The median agreement was 83.0% (interquartile range [IQR]: 76.6–89.5%; n = 33) for seizure and 99.7% (IQR: 98.9–99.8%; n = 70) for nonseizure EEG. Analysis of events showed a median agreement of 83.0% (IQR: 72.9–86.6%; n = 33) for seizures with 0.018 disagreements per hour (IQR: 0.000–0.090 per hour; n = 70). Observers were more likely to disagree when a seizure was less than 30 sec. Overall, 33 neonates were diagnosed with seizures and 28 neonates were not, by all three observers. Of the remaining nine neonates with contradictory EEG detections, seven presented with low total seizure burden. Interpretation The IOA is high among experts for the detection of neonatal seizures using conventional, multichannel EEG. Agreement is reduced when seizures are rare or have short duration. These findings support EEG-based decision making in the neonatal intensive care unit, inform EEG interpretation guidelines, and provide benchmarks for seizure detection algorithms.Peer reviewe