British journal of anaesthesia
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Intraoperative awareness, with or without recall, continues to be a topic of clinical significance and neurobiological interest. In this article, we review evidence pertaining to the incidence, sequelae, and prevention of intraoperative awareness. We also assess which aspects of the complication are well understood (i.e. non-controversial) and which require further research for clarification (i.e. controversial).
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Awareness during general anaesthesia is a source of concern for patients and anaesthetists, with potential for psychological and medicolegal sequelae. We used a registry to evaluate unintended awareness from the patient's perspective with an emphasis on their experiences and healthcare provider responses. ⋯ Data from this registry confirm the serious impact of anaesthesia awareness for some patients, and suggest that patients need more systematic responses and follow-up by healthcare providers.
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As opposed to conscious, personally relevant (explicit) memories that we can recall at will, implicit (unconscious) memories are prototypical of 'hidden' memory; memories that exist, but that we do not know we possess. Nevertheless, our behaviour can be affected by these memories; in fact, these memories allow us to function in an ever-changing world. It is still unclear from behavioural studies whether similar memories can be formed during anaesthesia. ⋯ Function of sensory cortices and thalamic activity during anaesthesia are reviewed. The role of sensory and perisensory cortices, in particular the auditory cortex, in support of memory function is discussed. Although improbable, with the current knowledge of neurophysiology one cannot rule out the possibility of memory formation during anaesthesia.
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General anaesthesia induces highly structured oscillations in the electroencephalogram (EEG) in adults, but the anaesthesia-induced EEG in paediatric patients is less understood. Neural circuits undergo structural and functional transformations during development that might be reflected in anaesthesia-induced EEG oscillations. We therefore investigated age-related changes in the EEG during sevoflurane general anaesthesia in paediatric patients. ⋯ Sevoflurane-induced EEG dynamics in children vary significantly as a function of age. These age-related dynamics likely reflect ongoing development within brain circuits that are modulated by sevoflurane. These readily observed paediatric-specific EEG signatures could be used to improve brain state monitoring in children receiving general anaesthesia.