title: Noxious stimulation in children receiving general anaesthesia evokes an increase in delta frequency brain activity.
abstract: More than 235,000 children/year in the UK receive general anaesthesia, but it is unknown whether nociceptive stimuli alter cortical brain activity in anaesthetised children. Time-locked electroencephalogram (EEG) responses to experimental tactile stimuli, experimental noxious stimuli, and clinically required cannulation were examined in 51 children (ages 1-12 years) under sevoflurane monoanaesthesia. Based on a pilot study (n=12), we hypothesised that noxious stimulation in children receiving sevoflurane monoanaesthesia would evoke an increase in delta activity. This was tested in an independent sample of children (n=39), where a subset (n=11) had topical local anaesthetic applied prior to stimulation. A novel method of time-locking the stimuli to the EEG recording was developed using an event detection interface and high-speed camera. Clinical cannulation evoked a significant increase (34.2 ± 8.3%) in delta activity (P=0.042), without concomitant changes in heart rate or reflex withdrawal, which was not observed when local anaesthetic was applied (P=0.30). Experimental tactile (P=0.012) and noxious (P=0.0099) stimulation also evoked significant increases in delta activity, but the magnitude of the response was graded with stimulus intensity, with the greatest increase evoked by cannulation. We demonstrate that experimental and clinically essential noxious procedures, undertaken in anaesthetised children, alter the pattern of EEG activity, that this response can be inhibited by local anaesthetic, and that this measure is more sensitive than other physiological indicators of nociception. This technique provides the possibility that sensitivity to noxious stimuli during anaesthesia could be investigated in other clinical populations.
authors.affiliation: Department of Paediatrics, University of Oxford, Oxford, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Hartley
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
authors.forename: Ravi
authors.initials: R
authors.lastname: Poorun
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
authors.forename: Sezgi
authors.initials: S
authors.lastname: Goksan
authors.affiliation: Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children, London, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Worley
authors.affiliation: Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children, London, UK.
authors.forename: Stewart
authors.initials: S
authors.lastname: Boyd
authors.affiliation: Nuffield Department of Anaesthesia, John Radcliffe Hospital, Oxford, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Rogers
authors.affiliation: Nuffield Department of Anaesthesia, John Radcliffe Hospital, Oxford, UK.
authors.forename: Tariq
authors.initials: T
authors.lastname: Ali
authors.affiliation: Department of Paediatrics, University of Oxford, Oxford, UK. Electronic address: rebeccah.slater@paediatrics.ox.ac.uk.
authors.forename: Rebeccah
authors.initials: R
authors.lastname: Slater
mesh_terms: D000768:Anesthesia, General / Q000379:methods*; D001921:Brain / Q000187:drug effects* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003700:Delta Rhythm / Q000187:drug effects*; D004562:Electrocardiography; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010146:Pain / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology*; D010812:Physical Stimulation / Q000009:adverse effects
keywords: Anaesthetics; EEG; Paediatrics