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Weird things happen in the Twilight Zone. Restlessness, Delirium, Limb
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1. Excitatory phenomena during induction of General Anaesthesia: a Molecular or Dynamic explanation? JW Sleigh1, M Steyn-Ross2, DA Steyn-Ross2
1Department of Anaesthetics, Waikato Clinical School, University of Auckland, Hamilton, NZ
2Department of Physics and Engineering, University of Waikato, Hamilton, NZ
2. Weird things happen in the Twilight Zone Restlessness, Delirium, Limb & eye Movements, Irregular respiration and Laryngospasm, Vomiting, EEG excitation, ANS activity
3. Explanations of Excitation? MOLECULES? Drugs acting on different ‘receptors’
NEURONS? Inhibition of the inhibitor cells
NEURAL POPULATION? Phase-transition
5. A Universal Phenomenon ? ? Universal Explanation? [Halsey & Smith (1970)]
8. Macrocolumn Model Cortex is a collection of inter-connected macrocolumns
Cortico-cortico connections
Extra-cortical input:
Scalp-measured EEG corresponds to ac component of he (mean excitatory soma potential)
9. EEG Power Surge @ Loss-of-Consciousness“Falls out for free”
10. Phase-transition – Increasing GA
11. Critical-Point Phenomena: the “footprints of a phase-transition” Critical “Slowing Down”
Increased Spatial Correlations
Exaggerated Responses to External Stimuli
12. John et al : Induction
13. Why Etomidate >> Thiopentone?
14. The Twittering Machine. Paul Klee
16.
EEG Activity vs Anaesthetic Concentration.
17. Predicted/Model “EEG” Spectrum
18. Clinical EEG: “Biphasic” Peaks
19. Power Surge: