British journal of anaesthesia
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Automated control of end-tidal inhalation anaesthetic concentration using the GE Aisys Carestation™.
Automated control of end-tidal inhalation anaesthetic concentration is now possible. The EtControl™ module of an Aisys Carestation Anaesthetic machine digitally adjusts fresh gas flow and plenum vaporizer output to achieve a target end-tidal concentration. ⋯ Automatic implementation of low-flow anaesthesia using EtControl allows the user to set and maintain a desired end-tidal volatile concentration while using less volatile agent.
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Positron emission tomography studies in human subjects show that propofol-induced unconsciousness in humans is associated with a reduction in thalamic blood flow, suggesting that anaesthesia is associated with impairment of thalamic function. A recent study showed that antagonism of propofol-induced unconsciousness by the anticholinesterase physostigmine is associated with a marked increase in thalamic blood flow, supporting the implication of the thalamus. The aim of the present study was to assess the role of the thalamus in the antagonistic effects of physostigmine during propofol anaesthesia using electrophysiological recordings in a rat model. ⋯ We conclude that partial antagonism of propofol anaesthesia by physostigmine is associated with an increase in thalamic activity reflected in gamma/high-gamma (50-200 Hz) power. These findings are consistent with the view that anaesthetic-induced unconsciousness is associated with impairment of thalamic function.