MS3 General Anesthesia Overview Department of Anesthesiology

58 Pages·2006·0.48 MB·English

GENERAL ANESTHESIA
Fatiş ALTINDAŞ
Associate Professor
Dept. of Anesthesiology
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General Anesthesia
(cid:132)A controlled reversible state of:
– Amnesia (loss of consciousness)
– Analgesia
– Akinesia (skeletal muscle relaxation)
– Autonomic and sensory reflex
blockade
(cid:132)Called the “4 A’s” of General
Anesthesia
(cid:132)General anesthesia is not the
same as the state of normal
sleep
–Controlled coma
–Without serious changes in vital
functions
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– Intravenous anesthetics
(cid:132) Sodium thiopental, propofol
– Inhalational anesthetics
(cid:132) Halothane, isoflurane, sevoflurane, desflurane
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Balanced Anesthesia: GA with several Agents
Regional Anesthesia: Using LA’s to anesthetize
a body region
Combined Technique: Regional plus “light” GA
Conscious Sedation: IV agents for analgesia/
anxiolysis maintaining
consciousness
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I.Inhalation agents: NEWER AGENTS OLDER DRUGS
Halothane Chloroform
Enflurane Ether
Volatile liquids: Isoflurane Ethylchloride
Desflurane Trichlorethylene
Sevoflurane
Gases: Nitrous oxide Cyclopropane
Ethylene
II. Intravenous agents
Thiopentone
Benzodiazepines
Etomidate
Ketamine
Propofol
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Mechanism of Actions of
General Anaesthetics
All drugs belong to diverse groups
– Inert gases as xenon
– Inorganic/Organic compds as Nitrous oxide and Chloroform
– Complex Organic Molecules
– Halogenated Alkanes and ethers
“The Mode of action is without any satisfactory explanation”
POSTULATIONS:
Influence synaptic transmission
Axonal conduction is unaffected
Potentiate release of inhibitory neurotransmitters
Inhibit excitatory synapses
Mechanism of Action
The exact mechanism by which
inhalational anesthetics function is not
known.
There appears to be a correlation
between anesthetic potency and lipid
solubility (Meyer-Overton theory),
suggesting that these anesthetics
likely affect the lipid matrix of nerve
cell membranes in the brain.