Drugs in Surgery Flashcards
What are the ways to take general anaesthetics (GAs)?
Inhalational
Intravenous
What are premedications?
Muscarinic antagonist
Analgesic
Local anaesthetic
Muscle relaxant
What do GAs do?
Abolish awareness and response to pain
Why are GAs used in surgery?
Loss of consciousness, including memory
Suppression of pain
Suppression of skeletal muscle reflexes and tone
What are the toxic effect of GAs?
Depresses b.p. and resiration (low therapeutic index)
Liver/kidney damage (rarely)
What are the characteristics of the ideal anaesthetic?
Quick induction High potency Reversibility Good analgesia Amnesia No hangover Low or harmless metabolism Non-flammability Muscle relaxation Low toxicity
What is quick inductio?
Low solubility in blood, giving rapid saturation of bloos
What is high potency?
High lipid solubility
What is reversibility?
Gases give good control, injection less so
What is low toxicity?
Respiratory depression
Cardiovascular depression
Liver damage
What are volatile/ gaseous anaesthetics?
Many, simple, unreactive compounds
Halothane and nitrous oxide are commonly used
What is the compositiong of volatile/gaseous anaesthetics?
Numerous simple, small molecules
Mostly very unreactive compounds
What happens with intravenous agents after injection
Very rapid (high cerebral blood flow) Very short duration (redistribution to other organs)
What is an example of an intravenous agent used?
Thiopentone (barbiturate)
What are the characteristics of thiopentone?
Low therapeutic index
Depresses heart and respiration
Repeat dose-> longer anaesthesia (slow metabolism)