Anaesthetics (year 2)

Question 1

what is the triad aims of anaesthesia?

Answer 1

muscle relaxation
unconsciousness
analgesia

Question 2

what are the three main injectable agents used in anaesthesia?

Answer 2

propofol, alfaxalone, ketamine

Question 3

what injectable agents can be used in anaesthesia?

Answer 3

propofol, alfaxalone, ketamine, thiopental, etomidate

Question 4

what are the two main anaesthetic agents used as inhalation agents?

Answer 4

isoflurane and sevoflurane

Question 5

what are the positives of injectable agents compared to inhalation agents?

Answer 5

injectable requires simple equipment and once administered it has to be metabolised and excreted to get rid of it

Question 6

what are the positives of inhalation agents compared to injectables?

Answer 6

inhalation the depth can easily be adjusted and it is delivered with oxygen

Question 7

what is the mode of action of propofol?

Answer 7

GABA agonist - reduces excitation in the brain

Question 8

describe the appearance of propofol

Answer 8

not water soluble so is an emulsion

Question 9

how is propofol administered?

Answer 9

IV

Question 10

propofol is lipid soluble what does this mean it can easily cross in the CNS?

Answer 10

blood-brain barrier

Question 11

where is propofol metabolised?

Answer 11

mainly the liver but also extrahepatic sites such as GIT

Question 12

what are the effects of propofol?

Answer 12

anaesthesia, sedation, muscle relaxation, anti-seizure

Question 13

what are the side effects of propofol?

Answer 13

vasodilation and blocks baroreceptor reflex so don’t get reflex tachycardia
respiratory depression due to altered carbon dioxide response
can cause oxidative damage to RBCs in cats

Question 14

what is the mechanism of action of alfaxalone?

Answer 14

GABA agonist

Question 15

what group of drugs is alfaxalone apart of?

Answer 15

neurosteroids

Question 16

is alfaxalone water soluble?

Answer 16

no but is made water soluble by addition of cyclodextrin

Question 17

why is alfaxalone made water soluble?

Answer 17

so it can be administered IV, IM or SC

Question 18

where is alfaxalone metabolised?

Answer 18

liver - no extrahepatic metabolism

Question 19

what are the effects of alfaxalone?

Answer 19

anaesthesia, sedation, muscle relaxation

Question 20

what are the side effects of alfaxalone?

Answer 20

vasodilation - baroreceptor reflex is maintained so get reflex tachycardia
respiratory depression
excitability on recovered with animals often being noise sensitive

Question 21

describe the mode of action of ketamine

Answer 21

NMDA antagonist

Question 22

what type of anaesthesia do you get with ketamine?

Answer 22

dissociative - disconnection of higher brain function from the body

Question 23

is ketamine water soluble?

Answer 23

yes

Question 24

how is ketamine administered?

Answer 24

IV, IM, SC, orally

Question 25

where is ketamine metabolised?

Answer 25

liver - except in cats it is excreted unchanged

Question 26

what are the effects of ketamine?

Answer 26

anaesthesia and analgesia

Question 27

what are the side effects of ketamine?

Answer 27

myocardial depression, increased HR, vasoconstriction, respiratory depression, muscle hypertonicity, cranial nerve reflexes maintained

Question 28

what does it mean if the cranial nerve reflexes are maintained when using ketamine?

Answer 28

animal will continue to swallow and blink

Question 29

what is the mechanism of action of thiopental?

Answer 29

GABA agonist

Question 30

how is thiopental administered?

Answer 30

IV - it is an irritant if administered extravascularly

Question 31

where is thiopental metabolised?

Answer 31

slowly in the liver

Question 32

what are the effects of thiopental?

Answer 32

anaesthesia, muscle relaxation, anti-seizure

Question 33

what are the side effects of thiopental?

Answer 33

myocardial depression, arrhythmogenic, respiratory depression

Question 34

what is MAC when relating to inhalation anaesthesia?

Answer 34

minimum alveolar concentration of an agent at which 50% of patients won't respond to noxious stimuli

Question 35

what is MAC measured as?

Answer 35

% of atmospheric pressure

Question 36

what time MAC is usually needed for surgery?

Answer 36

1.2-1.5 x MAC

Question 37

what effects MAC?

Answer 37

age, species, agents acting on CNS, pregnancy, low BP, body temperature

Question 38

what are the side effects of isoflurane and sevoflurane?

Answer 38

respiratory depression and potent vasodilation

Question 39

isoflurane is more pungent than sevoflurane what does this mean for the animals breathing?

Answer 39

tend to not breath as well on isoflurane

Question 40

is isoflurane or sevoflurane cheaper?

Answer 40

isoflurane