General anaesthetics Flashcards
What is the importance of anaesthesia?
Enables surgeons more time allowing increased accuracy
Able to enter more high risk areas such as the abdomen/chest/brain
What are the aims of general anesthesia? (3)
Loss of consciousness
Analgesia
Muscle relaxation
How do you measure anaesthetic action?
MAC (minimum alveolar concentration)
Define MAC
The concentration of vapour in the lungs that is needed to prevent movement in 50% of subjects exposed to painful stimuli
What are the central actions of general anaesthetics? (2)
Inhibit excitatory channels e.g. glutamate
Activate inhibitory channels e.g. GABAa
What are the peripheral actions of general anaesthetics? (3)
Cardiovascular - circulatory depression
Respiratory - respiratory depression
Muscular - relaxation
What are the FIVE stages of general anaesthesia?
Pre medication Induction Maintenance Muscle relaxation Pain relief
What are the aims of pre medication? (3)
Reduce anxiety and pain
Promote amnesia
Reduce vagal reflexes
What drug classes are there for pre medication? Give examples (4)
Benzodiazepines - Diazepam
mAChR antagonist - Atropine
Opioid receptor agonist - Morphine
PPI - Metoclopramide
What are the aims of induction?
Induce loss of consciousness
Name TWO drug inducers
Propofol
Barbituate e.g. Sodium Thiopental
Which inducer is favoured and why?
Propofol - rapid metabolism and lack of hangover effect
How does ketamine work?
Inhibits excitatory NMDA glutamate receptors
What is the aim of maintenance?
Maintain loss of consciousness
Name TWO drugs used for maintenance
Halothane
Nitrous Oxide
