small animal anaesthesia

Question 1

what are the four classes of sedatives?

Answer 1

APBB
1. Alpha-2-agonist
2. phenothiazines
3. Butyrophenones (not rly used)
4. Benzodiazepines

Question 2

give an example of an A2-agonist and what are their properties

Answer 2

medetomidine, xylazine
sedation, analgesia, muscle relaxation.
cause vasoconstriction and reflex bradycardia.
increases urine production
Atipamezole=reversal agent
immediate onset

Question 3

give an example of a phenothiazine and what is its properties

Answer 3

Acerpromazine
sedation, muscle relaxation but NO analgesia
vasodilator
20-40 min onset.
Used in patients with mitral valve disease, BOAS, URT disease, laryngeal paralysis.
very useful if nervous patient

Question 4

give an example of a benzodiazepine and what are its properties

Answer 4

Diazepam, Midazolam, Dormazolam.
sedation, smooth muscle relaxationbut NO analgesia.
minimal side effects but unreliable sedation.
5 min onset IV
Flumazenil=reversal agent

Question 5

What are the SIX analgesic classess

Answer 5

NO PLAN
1. NSAID’s
2. Opioids
3. Paracetamol
4. Local anaesthetic
5. Alpha-2-agonist
6. NMDA antagonist

Question 6

What are the three opioids used in small animal

Answer 6

1. Methadone
   full mu agonist, painful procedures
2. Buprenorphine
   partial mu agonist, moderatley painful procedures
3. Butorphanol
   kappa agonist, mu ANTagonist, non painful procedures only sedation needed

Question 7

What are the THREE induction agents used in SA

Answer 7

1. Propofol
2. Alfaxolone
3. Ketamine

Question 8

what are the properties of propofol and how is it metabolised

Answer 8

vasodilation, respiratory depression.
Recovery due to redistribution, hepatic metabolism.
*only give one dose to cats as very poor at propofol metabolisation (cause heinz body anemia)

*baroreflex abolished

Question 9

what are the properties of alfaxolone and how is it metabolised

Answer 9

Vasodilation, respiratory depression, baro reflex intact.
recovery due to redistribution, hepatic metabolism.
*excitable recovery for noise sensitive individuals

Question 10

what are the properties of ketamine and how is it metabolised

Answer 10

Dissociative anaesthesia
Muscle hypertonicity, maintenance of CN reflexes, tachycardic, vasoconstrictive.
Hepatic metabolism, urine excretion

Question 11

What can be given to anxious patients prior to the appointment

Answer 11

gabapentin (dog/cat)
trazadone (dog)

Question 12

give an example of a dog sedation protocol (no underlying CV disease present)

Answer 12

medetomidine
opioid
ketamine
(IM)

Question 13

why is inclusion of a benzoidiazepine useful for nervous patients during some point of sedation

Answer 13

retrogade amnesic effects.
Wont be able to remember the traumatic trip to the vets. make future appointments easier

Question 14

give an example of a cat sedation protocol (no underlying CV disease present)

Answer 14

medetomidine
opioid
ketamine

Question 15

give an example of a cat sedation where CV disease present

Answer 15

alfaxolone
butorphanol
midazolam

Question 16

what circuit would you use for dogs <10kg

Answer 16

Mapleson D

Question 17

what is the normal ET CO2 level seen on capnograph?

Answer 17

35-45mmhg
normal for it to be in the 50s at first due to post induction apnoea

Question 18

what does the capnograph tell us about respiration?

Answer 18

Peak below 40= hyperventilation
Peak above 70= hypoventilation
Lowest point never reaching 0= rebreathing
Jagged on inspiration= cardiac oscillations, not significant
Gradually declining peak= leak or dying

Question 19

what is the minimum mean alveolar blood pressure required during anaesthesia?

Answer 19

Need mean arterial pressure (MAP) to be at 60 minimum as a pressure difference of 50 is needed to allow perfusion. The normal intracranial pressure is around 10, so need a MAP of 60 to ensure the brain is properly perfused.

Question 20

what are the SIX agents used for maintiaining blood pressure

Answer 20

1. Fluid boluses
2. Medetomidine
3. Dopamine
4. Atropine
5. Glycopyrrolate
6. Dobutamine

Question 21

At what rate would you give an anaesthetised patient a fluid bolus to maintain BP

Answer 21

10-20ml/kg/hr over a 15-20 minute period.
Don’t give if underlying CV compromise

Question 22

How much medetomidine would you give during anaesthesia to maintain BP

Answer 22

1/4 dose to increase BP through vasoconstriction.
This wears off very quickly so only useful for short term

Question 23

How is dopamine given to improve BP?

Answer 23

commonly given as an infusion via a syringe driver.
a vasoconstrictor at higher dose however not a positive ionotrope. Only give if heart rate is satisfactory

Question 24

How does atropine increase BP

Answer 24

it is a parasympatholytic (inhibits rest and digest)
Causes vasoconstriction and increased heart rate

Question 25

How does dobutamine work differently to all the other BP agents?

Answer 25

dobutamine is a positive ionotrope. It does not cause vasoconstriction.
Commonly used in horses for this very reason as vasoconstriction would restrict blood flow to peripheral tissues and could cause myopathies

Question 26

What is your main concern with a neurologic patient?

Answer 26

possibility for an abnormal/increased intracranial pressure. Higher blood pressure required to allow brain perfusion.
Hypercapnia and hypertension are my two biggest concerns

Question 27

why is hypercapnia a concern in a neurologic patient?

Answer 27

hypercapnia further increases ICP as vessles in the brain vasodilate

Question 28

should methadone be given to an neurologic patient?

Answer 28

no if possible. Can cause increased ICP

Question 29

how does glycopyrrolate increase BP

Answer 29

parasympatholytic like atropine however has less side effects.
Expect patient to be tachycardic for a long period following administration

Question 30

When is glycopyrrolate contraindicated and why

Answer 30

contraindicated when medetomidine has been given.
Get a sustained run of abnormal ventricular rythms and high BP as a result

Question 31

whys is sevoflurane generally considered safer than isoflurane

Answer 31

Causes less vasodilation and has a higher MAC therefore takes effect/wears off faster.