Anaesthetic agents Flashcards
Ideal properties of anaesthetic agent
stable
no preservatives
not flamable
cheap
ozone friendly
non metabolised
nont oxic
no CVS effects
analgesic
factors affecting blood stream concentration
ventilation
concentration of agent in gas
cardiac output (inverse)
solubility of agent in body (inverse)
solubility
ratio of amount of anaesthetic in blood and gas when the two are in equal pressure and volume
less soluble - low coefficient - washed away less quickly so faster rise in alveolar concentration
effect of fat
anaesthetic agent redistributes into fat
stores anaesthetic
so slower recovery
unwanted effects of inhaled agents
CVRS depression
formation of CO with soda lime
effects on anaesthetist - bone marrow suppression, teratogenesis
nitrous oxide
expensive
health and safety issues
ozone gas
high MAC
analgesic
minimal CVRS effects
halothane
lower MAC
isoflurane
low solubility - good
vasodilation
hypotension
some CVRS depression
MAC -
dog - 1.28
cat - 1.63
Sevoflurane
higher MAC than iso
otherwise same effects
Minimum alveolar concentration (MAC)
Alveolar concentration producing immobility in 50% of patients
MAC affected by
age
nitrous
hypotension
anaemia
opioids
sedatives
local anaesthetics
pregnancy
MAC not affected by
stimulation
duration
species
sex
CO2
NSAIDs
TIVA
eg. quad protocol for cats
field procedure in horses - GGE, ketamine, alpha 2
still need to protect airway and supply oxygen
PIVA
reduce MAC and cardiopulmonary depression
provide additional analgesia
improved environmental impact
less organ toxicity
IV drugs may accumulate over time
needs additional equipment
CV evaluation
eye position
jaw tone
EEG
bispectral index - 40-60
end tidal anaesthetic agent
blood pressure
pulses - compare - dorsal metatarsal disppears with hypotension
ECG
pulses - femoral, dorsal metatarsal, lingual, auricular
