Anesthetic Induction Flashcards

1
Q

What happens during anesthetic induction?

A

Sleep induction
Skeletal muscle relaxation
Loss of reflexes
Endotracheal intubation

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2
Q

What is the ultimate goal of anesthetic induction?

A

Controlled anesthesia

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3
Q

How do we judge an animal that is at stage 3 anesthesia?

A

Loss of righting reflex

Not surgical plane

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4
Q

What are the stages of anesthesia?

A

Stage 1: analgesia
Stage 2: disinhibtion
Stage 3: surgical anesthesia
Stage IV: medullary depression

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5
Q

How can you get the animal calm before induction?

A

Premedication

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6
Q

Why do you want the animal calm before induction?

A
Stress increases epinephrine levels
Elevates sympathetic tone
Epinephrine is arrythmogenic
Fight or flight
Poor inductions leads to poor recoveries
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7
Q

Do most induction drugs have a low or high therapeutic index?

A

Low (narrow safety margins_

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8
Q

How much should be given of induction drugs?

A

Give to effect, so until the animal is unconscious and can be intubated

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9
Q

What would the ideal anesthetic agent be?

A
Smooth loss of consciousness
Analgesia and relaxation
Wide safety margin
Not controlled
Minimal to no metabolism
Inexpensive
But does not exist
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10
Q

What are the injectable induction agents?

A

GABA agonists
NMDA antagonists
Opioids

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11
Q

What are the GABA agonists?

A

Propofol
Etomidate
Alfaxalone
Thiopental (C-III controlled substance)

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12
Q

What are the NMDA antagonists?

A

Ketamine

Telazol (tiletamine-zolazepam)

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13
Q

What is the mechanism of action of thiopental?

A

Bind to GABAa receptor and enhance GABA effect and directly stimulate causing increased chloride current and hyperpolarization
Reduces CMRO2, ICP, and CBF but preserves CPP due to greater drop in ICP than MAP

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14
Q

What are the effects of thiopental?

A

Respiratory depression
Arrhythmias, hypotension
No analgesia

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15
Q

What is the technique for giving thiopental?

A

Small animals: one-half as initial bolus
Wait 30 seconds
Titrate to effect
Large animals: give entire calculated dose

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16
Q

What is the mechanism of action for propofol?

A

Hypnotic
Enhances GABA inhibition
Mild NMDA inhibition

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17
Q

Does propfol provide analgesia?

A

No

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18
Q

How is propofol metabolized?

A

Extra-hepatically

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19
Q

What is the onset of action IV for propofol?

A

10-30 seconds

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20
Q

What is the duration of action of propofol?

A

3-7 minutes

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21
Q

What is the drug of choice for C-sections? Why?

A

Propofol

Crosses the placenta, but clears rapidly from neonatal circulation

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22
Q

What are the cardiovasulcar side effects of propofol?

A

Vasodilation –> hypotension
Bradycardia
Impaired baroreceptor response

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23
Q

What are the pulmonary side effects of propofol?

A

Decreased respiratory rate and tidal volume

Apnea

24
Q

What does propofol cause at induction?

A

Excitement

25
Q

What kind of metabolism does propofol undergo?

A

Both hepatic and extra-hepatic

26
Q

What redistribution does propofol undergo?

A

Extensive and rapid tissue redistribution

27
Q

What happens to cats with every day dosing of propofol?

A

Hemolysis
Lethargy
Anorexia

28
Q

What is a propofol/ketamine mix?

A

Reduced dose of each
50:50 mix in same syringe
Rapid, reliable, effective, chemically stable, bacteriostatic

29
Q

What is the technique of administering propofol?

A

Slow IV over 30 to 60 seconds
If it is too fast, the will have apnea, cyanosis, and bradycardia
Flow by O2

30
Q

What is alfaxalone?

A

Neuroactive steroid that enhances GABA inhibition

31
Q

Does alfaxalone provide analgesia?

A

No

32
Q

What are the cardiovascular side effects of alfaxalone?

A

Cat: decreased HR and BP
Dog: marked increased HR, no change in BP

33
Q

What are the pulmonary side effects of alfaxalone?

A
Decreased  RR (Apnea)
Decreased tidal volume (minimal)
34
Q

What does alfaxalone cause at recovery?

A

Excitation

35
Q

What are ketamine and tiletamine?

A

NMDA antagonists

Dose-dependent restraint to anesthesia

36
Q

What is the onset of ketamine and tiletamine?

A

60 seconds after IV, 5-10 minutes after IM, SC

37
Q

What are the effects of ketamine?

A

Long-lasting motor effects after IM
Poor relaxation alone (add tranquilizer, benzodiazepines)
Inadequate analgesia for acute pain with single dose

38
Q

What is telazol?

A

A combination of tiletamine HCl (NMDA antagonsit) and zolazepam HCl (benzodiazepine)

39
Q

What do high dosages of Telazol lead to?

A

Prolonged recovery

40
Q

What is Telazol commonly mixed with for injectable anesthesia?

A

Alpha-2 agonist and ketamine

41
Q

What is etomidate?

A

GABAa agonist

Non-barbiturate sedative-hypnotic injectable anesthetic agent

42
Q

What is the clinical use of etomidate?

A

Cardiac animals

43
Q

What is the technique for etomidate?

A

Give slow IV, titrate
Administer with IV fluids to decrease pain
Patient must be well sedated before use
Rapid onset, short duration

44
Q

What are the effects of etomidate?

A

Minimal effects on cardiovascular
Respiratory function maintained
Suppresses adrenocortical steroidogenesis

45
Q

What are opioid combinations used in?

A

Debilitated dogs

46
Q

What can opioid combinations produce?

A

Bradycardia

Cardiovascular stability

47
Q

What are examples of opioid combinations?

A

Hydromorphone, fentanyl, methadone + diazepam or midazolam IV

48
Q

What is guaifenesin?

A

Centrally-acting muscle relaxant used as an anesthetic adjunct in large animals

49
Q

What are the effects of guaifenesin?

A

Very irritating with acidental perivascular injection

50
Q

What inhalational agents are useful for induction?

A

Isoflurane
Sevoflurane
Desflurane

51
Q

When should you use caution with inhalation agents?

A

With stressed animals due to high epinephrine levels

52
Q

What is chamber induction used for?

A

Small animals/exotics

Small, really upset animals

53
Q

What is the oxygen flow rate like in chamber induction?

A

High

54
Q

What is the inhalant concentration like in chamber induction?

A

High

55
Q

What is mask induction used for?

A

Pocket pets, birds/exotics, neonates, and pediatrics

56
Q

What do you do after anesthetic induction?

A

Intubate
Connect breathing system
Turn on vaporizer
Check vital signs- airway, breathing, circulation