title: Xenon depresses aEEG background voltage activity whilst maintaining cardiovascular stability in sedated healthy newborn pigs.
abstract: BACKGROUND
  Changes in electroencephalography (EEG) voltage range are used to monitor the depth of anaesthesia, as well as predict outcome after hypoxia-ischaemia in neonates. Xenon is being investigated as a potential neuroprotectant after hypoxic-ischaemic brain injury, but the effect of Xenon on EEG parameters in children or neonates is not known. This study aimed to examine the effect of 50% inhaled Xenon on background amplitude-integrated EEG (aEEG) activity in sedated healthy newborn pigs.
  
  
  METHODS
  Five healthy newborn pigs, receiving intravenous fentanyl sedation, were ventilated for 24 h with 50%Xenon, 30%O2 and 20%N2 at normothermia. The upper and lower voltage-range of the aEEG was continuously monitored together with cardiovascular parameters throughout a 1 h baseline period with fentanyl sedation only, followed by 24 h of Xenon administration.
  
  
  RESULTS
  The median (IQR) upper and lower aEEG voltage during 1 h baseline was 48.0 μV (46.0-50.0) and 25.0 μV (23.0-26.0), respectively. The median (IQR) aEEG upper and lower voltage ranges were significantly depressed to 21.5 μV (20.0-26.5) and 12.0 μV (12.0-16.5) from 10 min after the onset of 50% Xenon administration (p=0.002). After the initial Xenon induced depression in background aEEG voltage, no further aEEG changes were seen over the following 24h of ventilation with 50% xenon under fentanyl sedation. Mean arterial blood pressure and heart rate remained stable.
  
  
  CONCLUSIONS
  Mean arterial blood pressure and heart rate were not significantly influenced by 24h Xenon ventilation. 50% Xenon rapidly depresses background aEEG voltage to a steady ~50% lower level in sedated healthy newborn pigs. Therefore, care must be taken when interpreting the background voltage in neonates also receiving Xenon.
authors.affiliation: School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom; Departments of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Düsseldorf, Heinrich-Heine University Düsseldorf, Germany.
authors.forename: Hemmen
authors.initials: H
authors.lastname: Sabir
authors.affiliation: Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wood
authors.affiliation: School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom.
authors.forename: Hannah
authors.initials: H
authors.lastname: Gill
authors.affiliation: School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom.
authors.forename: Xun
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Medicine, Swansea University, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Dingley
authors.affiliation: School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom; Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway. Electronic address: marianne.thoresen@medisin.uio.no.
authors.forename: Marianne
authors.initials: M
authors.lastname: Thoresen
mesh_terms: D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D008297:Male; D013552:Swine; D014978:Xenon / Q000008:administration & dosage*
chemical_list: D018686:Anesthetics, Intravenous; D014978:Xenon; D005283:Fentanyl
keywords: Amplitude-integrated encephalography; Inhalation anaesthetics; Newborn; Xenon