Noxious stimulation in children receiving general anaesthesia evokes an increase in delta frequency brain activity
Caroline Hartley1, Ravi Poorun2, Sezgi Goksan2
1Department of Paediatrics, University of Oxford, Oxford, UK.
Insights
Noxious stimuli, like medical procedures, alter brain activity in anaesthetised children, indicated by increased delta waves on electroencephalogram (EEG) readings. This response to pain can be blocked by local anaesthetic, suggesting EEG is a sensitive measure of nociception.
Area of Science:
- Neuroscience
- Anesthesiology
- Pediatrics
Background:
- General anaesthesia is administered to over 235,000 children annually in the UK.
- The impact of nociceptive stimuli on cortical brain activity in anaesthetised children remains largely unknown.
- Existing physiological indicators may not accurately reflect nociception during anaesthesia in pediatric patients.
Purpose of the Study:
- To investigate whether nociceptive stimuli alter cortical brain activity in children under sevoflurane anaesthesia.
- To determine if electroencephalogram (EEG) delta activity changes in response to tactile, noxious, and clinical stimuli.
- To assess the efficacy of local anaesthetic in inhibiting EEG responses to noxious stimuli.
Main Methods:
- Examined time-locked EEG responses to experimental tactile, noxious, and clinical cannulation stimuli in 51 children (ages 1-12) under sevoflurane monoanaesthesia.
- Developed a novel method using an event detection interface and high-speed camera for precise stimulus time-locking to EEG.
- Compared EEG delta activity changes between stimulated groups and a subset receiving topical local anaesthetic.
Main Results:
- Clinical cannulation significantly increased EEG delta activity (34.2 ± 8.3%, P=0.042) without altering heart rate or reflex withdrawal.
- Experimental tactile and noxious stimuli also significantly increased delta activity, with responses graded by stimulus intensity.
- Local anaesthetic application prior to stimulation abolished the EEG delta activity response (P=0.30).
Conclusions:
- Noxious procedures in anaesthetised children demonstrably alter EEG patterns, specifically increasing delta activity.
- The observed EEG response to noxious stimuli can be inhibited by local anaesthetic.
- EEG delta activity changes represent a sensitive measure of nociception during anaesthesia, potentially more so than traditional physiological indicators.
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.
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