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12 Cards in this Set
- Front
- Back
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General anaesthesia
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render patients unaware of, and unresponsive to, painful stimulation during surgical procedures
aim: induce unconsciousness, analgesia and muscle relaxation - used in combination functions: decrease CNS activity, depress CV, RS and other systems |
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Adjunct medication for General anaesthesia
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given before and after surgery to calm the patient, protect against undesirable effects of anaesthesia and relieve pain.
pre: benzodiazepines, H2 blockers, antimuscarinic drugs, neuromuscular blockers post: analgesics, antiemetics |
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Properties of general anaesthetia
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small lipid soluble molecules
administered systemically (IV/inhalation) |
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Theories of the mechanism of action of general anaesthetics
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no single molecular mechanism of action for all
physicochemical theories/ lipid soluble theory anaesthetic effect is exerted through some perturbation of the lipid bilayer structural theory anaesthetic effect is exerted through interactions with proteins (ion channels) |
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physicochemical theories/ lipid soluble theory
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anaesthetic effect is exerted when sufficient amount of the GA dissolves in the lipid bilayer - alters the excitability of the cell membrane
meyer-overton rule: GA > soluble in lipid = > potent |
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structural theory
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acts on ligand gated ion channels
excitatory receptors (NA, 5HT, NMDA) are inhibited by GA inhibitory receptors (GABA-A, gly) are potentiated by GA potentiate the action of GABA at the GABA-A receptor |
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Stages of anaesthesia
Stage I |
Analgesia
Amnesia, Euphoria |
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Stages of anaesthesia
Stage II |
Excitement
Delirium, Combative behaviour |
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Stages of anaesthesia
Stage III |
Surgical anaesthesia
Unconsciousness, regular respiration and decreasing eye movement recovery via withdrawal of GA |
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Stages of anaesthesia
Stage IV |
Medullary Depression
respiratory arrest, cardiac depression and arrest, no eye movement |
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Main inhalation anaesthetic agents
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volatile
iso/sevo/des-flurane NitrOUS oxide maintain stage III |
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Main IV anaesthetic agents
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propofol, thiopentone, ketamine
rapid induction of stage I and II |
