Pharmacology Flashcards
what is the triad of anaesthetise?
muscle relaxant
hypnosis
analgesia
what components of the triad of anaesthesia does local anaesthetics involve?
analgesia
muscle relaxant
how does local aesthetics work?
block Na channels therefore inhibit depolarisation and transmission
what components of the triad of anaesthesia does general anaesthesia involve?
hypnosis
muscle relaxant
analgesia (only ketamine does)
what are the differences between inhaled and IV general aesthetics?
inhaled - slow uptake but long duration
IV - rapid uptake but quick duration
inhaled = dissolves in the membrane IV = allosteric binding by GABA receptors
what components of the triad of anesthesia does opiates involve?
hypnosis
analgesia
how does general aesthetics work?
they open Cl channels = hyper polarisation therefore reducing firing of action potentials
how is potency measured with inhalation general anaesthetics?
mean alveolar concentration (MAC)
how much concentration within the alveoli to cause an effect
smaller the number the higher he potency
describe the uptake of IV general anaesthetics.
rapid uptake from the circulation but rapid clearance
viscera has a slower uptake
muscle has an even slower uptakes but a longer duration due to the mass of skeletal muscle in the body
fat has a long uptake and long duration as it is able to store it in fatty tissue due to the fat solubility of G.A
what part of the body is affected by G.A. first?
the brain
cerebral junction is lost from top down
when are muscle relaxants required?
when you need access to a body cavity
when immobility is essential i.e. neurosurgery, microscopic surgery
ventilation and intubation is required
what are the problems associated with muscle relaxants?
insufficient hypnotic can lead to awareness
incomplete reversal
apnoea (with dependance on ventilation)
why is analgesia required during an operation?
to prevent arousal
suppress reflex response to painful stimuli i.e. hypertension, tachycardia
opiats also contribute to hypnotic effect of G.A.
what are the benefits of local anaesthetic compared to general anaesthetics?
retain awareness
lack of systemic effects of general
relative sparing of respiratory physiology (therefore better in people with respiratory problems)
why might local anaesthesia be preferred instead of general in someone with severe athsma but wouldn’t be so beneficial in someone with congestive heart failure?
local anesthetic has relative sparing of respiratory physiology but it sill causes derangement of the CVS physiology
