General anaesthetics Flashcards
Name 5 ancient non-drug alternatives to general anaesthetics
Blood letting, nerve compression, concussion, carotid compression, hyponosis
Name 3 early anaesthetics
Nitrous oxide, ether, chloroform
Name the 4 stages of anaesthesia
Analgesia, excitement, surgical anaesthesia, viral centre depression
What 4 things make the ideal anaesthetic?
Wide margin of safety, rapid onset, readily reversible and no toxicity
What drugs are used for induction of anaesthesia?
IV thiopentone and propofol
What drugs are used for maintenance of anaesthesia?
Inhaled nitrous oxide and isoflurane
How do general anaesthetics work?
Descending action on brain centres
Decreased conciousness&memory, motor&sensory skills, reasoning and inhibitions
What two mechanism theories are there?
Lipid theory (dissolve in neuronal membrane and change its fluidity) Protein theory (dissolve in membranes and interact with lipid pockets in membrane proteins and ion channels)
Why is lipid solubility a key property?
Determines both rate of onset and potency-> can cross BBB and interact with receptors
What is thiopentane?
IV anaesthetic, rapid onset and short duration of action and a long metabolic half life
Actions terminated by redistribution away from brain
What is propofol?
IV anaesthetic, rapid onset, short duration and short metabolic half life
Can be given by infusion for longer periods
Why are gaseous anaesthetics used for maintenance?
Poorly soluble in blood and highly lipid soluble
Slow onset
What is nitrous oxide used for?
Weak anaesthetic so used to carry more potent anaesthetics (isoflurane)
Also used in labour
What is isoflurane used for?
Strong inhaled anaesthetic for maintenance (slow onset), carried by nitrous oxide
Name 2 alternatives to isoflurane
Desflurane and sevoflurane
