Anaesthetics (PD Week 2) Flashcards
What is a general anaesthesia
a state of uncontrolled unconsciousness. Medicines used to send you to sleep in surgery
What is local anaesthesia
targeted area of the body is numbed and you remain full conscious e.g. for fillings
What are the 4 stages of general anaesthesia
- analgesia - conscious
- excitation - delirium with struggle, rapid respiration, eye movements (dilated)
- surgical anaesthesia - loss of consciousness divided into 4 planes
- medullary depression - loss of spontaneous respiration and depression of cardiovascular reflex - avoid as it could lead to overdose
What are the 2 main mechanisms of action for General anaesthetics
- inhibit excitatory LGIC (NMDA Receptors)
- enhance sensitivity of inhibitory ion channels (GABAa receptor)
Name 3 drugs that enhance GABAa receptor activity (potentiate)
- Propofol
- etomidate
- thiopental
Name 2 drugs that inhibit NMDA and ACh receptors
- nitric oxide
- ketamine
General anaesthetics potentiate activity of..
- GABAa receptors
- Glycine receptors
General anaesthetics inhibit activity of…
- NAChR
- 5HT3
- NMDA
Name 2 intravenous anaesthetics
- propofol
- ketamine
Name 2 inhalation anaesthetics
- nitrous oxide
- isoflurane
What is the ideal blood:gas coefficient of a GA
lower
as it has faster onset and faster emergence from the anaesthesia (equilibrium is reached sooner)
What is the ideal oil:gas coefficient
high but not too high as recovery would be delayed as it would remain in the fatty tissue
What is the mechanism of action of local anaesthetics
they block Na+ channels which prevent an action potential firing
What are 2 LA pathways into the neuronal axon
- hydrophobic pathway (non-use dependent)
- hydrophilic pathway (use-depenedent)
LA have a use dependent block - do the Na+ channels have to be open or closed
open so the LA can bind to the receptors in the channel
