Aneasthetics Flashcards
Anaesthetics vs analgesic
Prevent vs control pain
What kind of receptors do anaesthetics interact with?
Ligand gated
How are inhalation anaesthetics affected by blood solubility?
Lower blood solubility = less drug transferred to lungs to reach equilibrium so rapid induction and recovery
How do pharmacokinetics effect inhaled anaesthetics?
a) ventilation
b) vascularisation
a) higher ventilation rate = faster removal
b) higher vascularisation = increased distribution
How is most of an inhaled anaesthetic removed?
Lungs not metabolism
Side effects of inhaled anaesthetics
Increased sympathetic effects, hypotension, respiratory depression
What receptor to IV anaesthetics have high affinity for?
GABA
Mechanism for action for LA?
Block electrical signalling (action potential) in neurone by blocking voltage gated Na + ion channels
Most LA are weak bases why is this important?
They will only be unionised (an able to cross membrane) in basic solution
Outside of neurone is basic so they can cross them membrane
Inside of receptor is acidic = ionised so they bind and stay there
How to increase duration of LA?
Co-administer with adrenaline to cause vasoconstriction
How to increase speed fo onset of LA?
Administer in slightly alkaline solution so more is unionised
Are all nerves susceptible to LA?
No
Smaller diameter = easier to block
Nociceptive are smaller than motor - so more susceptible
What is “use dependent block”
Depth of block increases as the frequency of the action potential increases
Why does use dependent block occur?
LA have higher affinity for nerves in the open/inactive state (not resting), so increasing the time they are active for will increase the effect
Why are LA less effective in inflamed tissue?
More acidic = more ionised
