General anaesthetics Flashcards
What do general anaesthetic regulate?
The activity of neuronal ion channels- different GAs effect different ion channels
What do volatile GAs bind to?
a+B subunits of GABAa
What do intravenous GAs bind to?
B subunit of GABAa
What do low concentrations of volatile GAs bind to?
Pore domain K channels
What do low concentrations of GAs do to synaptic transmission?
Decrease synaptic transmission in CNS, which causes unconsciousness because of effect on reticular formation, short term amnesia due to effect on hippocampus
What do high concentrations of GAs do to synaptic transmission?
Decrease conduction in CNS and PNS, resulting in loss of motor control , reflexes, respiration and autonomic regulation
What happens in the analgesia phase of GA and why?
Lose responsiveness to pain due to effects of thalamic nuclei
Why does the excitement stage occur?
Due to effects on reticular formation
What happens in surgical anaesthesia?
Unconsciousness, loss of responsiveness to painful stimulation, loss of reflexes, short term amnesia
What are the advantages of propofol?
Rapid metabolism, induction of anaesthetic t=0.5 2-4 minute with rapid recovery so less hangover, useful for day case surgery
What are 3 examples of intravenous GAs?
Thiopental, etomidate, Propofol
What are disadvantages of thiopental?
High lipid solubility so rapid induction but also short duration of action due to redistribution and hangover due to accumulation in body fate, respiratory and CVS depression
What are the disadvantages of Etomidate?
Excitatory effects during induction and recovery, adrenocortical suppression
What are the advantages of Etomidate?
Fast onset. fairly fast recovery, less CVS depression
What are the side effects of propofol?
CVS and respiratory depression
