Anesthetic Induction

Question 1

What happens during anesthetic induction?

Answer 1

Sleep induction
Skeletal muscle relaxation
Loss of reflexes
Endotracheal intubation

Question 2

What is the ultimate goal of anesthetic induction?

Answer 2

Controlled anesthesia

Question 3

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

Answer 3

Loss of righting reflex

Not surgical plane

Question 4

What are the stages of anesthesia?

Answer 4

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

Question 5

How can you get the animal calm before induction?

Answer 5

Premedication

Question 6

Why do you want the animal calm before induction?

Answer 6

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

Question 7

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

Answer 7

Low (narrow safety margins_

Question 8

How much should be given of induction drugs?

Answer 8

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

Question 9

What would the ideal anesthetic agent be?

Answer 9

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

Question 10

What are the injectable induction agents?

Answer 10

GABA agonists
NMDA antagonists
Opioids

Question 11

What are the GABA agonists?

Answer 11

Propofol
Etomidate
Alfaxalone
Thiopental (C-III controlled substance)

Question 12

What are the NMDA antagonists?

Answer 12

Ketamine

Telazol (tiletamine-zolazepam)

Question 13

What is the mechanism of action of thiopental?

Answer 13

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

Question 14

What are the effects of thiopental?

Answer 14

Respiratory depression
Arrhythmias, hypotension
No analgesia

Question 15

What is the technique for giving thiopental?

Answer 15

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

Question 16

What is the mechanism of action for propofol?

Answer 16

Hypnotic
Enhances GABA inhibition
Mild NMDA inhibition

Question 17

Does propfol provide analgesia?

Answer 17

No

Question 18

How is propofol metabolized?

Answer 18

Extra-hepatically

Question 19

What is the onset of action IV for propofol?

Answer 19

10-30 seconds

Question 20

What is the duration of action of propofol?

Answer 20

3-7 minutes

Question 21

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

Answer 21

Propofol

Crosses the placenta, but clears rapidly from neonatal circulation

Question 22

What are the cardiovasulcar side effects of propofol?

Answer 22

Vasodilation –> hypotension
Bradycardia
Impaired baroreceptor response

Question 23

What are the pulmonary side effects of propofol?

Answer 23

Decreased respiratory rate and tidal volume

Apnea

Question 24

What does propofol cause at induction?

Answer 24

Excitement

Question 25

What kind of metabolism does propofol undergo?

Answer 25

Both hepatic and extra-hepatic

Question 26

What redistribution does propofol undergo?

Answer 26

Extensive and rapid tissue redistribution

Question 27

What happens to cats with every day dosing of propofol?

Answer 27

Hemolysis Lethargy Anorexia

Question 28

What is a propofol/ketamine mix?

Answer 28

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

Question 29

What is the technique of administering propofol?

Answer 29

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

Question 30

What is alfaxalone?

Answer 30

Neuroactive steroid that enhances GABA inhibition

Question 31

Does alfaxalone provide analgesia?

Answer 31

No

Question 32

What are the cardiovascular side effects of alfaxalone?

Answer 32

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

Question 33

What are the pulmonary side effects of alfaxalone?

Answer 33

``` Decreased RR (Apnea) Decreased tidal volume (minimal) ```

Question 34

What does alfaxalone cause at recovery?

Answer 34

Excitation

Question 35

What are ketamine and tiletamine?

Answer 35

NMDA antagonists | Dose-dependent restraint to anesthesia

Question 36

What is the onset of ketamine and tiletamine?

Answer 36

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

Question 37

What are the effects of ketamine?

Answer 37

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

Question 38

What is telazol?

Answer 38

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

Question 39

What do high dosages of Telazol lead to?

Answer 39

Prolonged recovery

Question 40

What is Telazol commonly mixed with for injectable anesthesia?

Answer 40

Alpha-2 agonist and ketamine

Question 41

What is etomidate?

Answer 41

GABAa agonist | Non-barbiturate sedative-hypnotic injectable anesthetic agent

Question 42

What is the clinical use of etomidate?

Answer 42

Cardiac animals

Question 43

What is the technique for etomidate?

Answer 43

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

Question 44

What are the effects of etomidate?

Answer 44

Minimal effects on cardiovascular Respiratory function maintained Suppresses adrenocortical steroidogenesis

Question 45

What are opioid combinations used in?

Answer 45

Debilitated dogs

Question 46

What can opioid combinations produce?

Answer 46

Bradycardia | Cardiovascular stability

Question 47

What are examples of opioid combinations?

Answer 47

Hydromorphone, fentanyl, methadone + diazepam or midazolam IV

Question 48

What is guaifenesin?

Answer 48

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

Question 49

What are the effects of guaifenesin?

Answer 49

Very irritating with acidental perivascular injection

Question 50

What inhalational agents are useful for induction?

Answer 50

Isoflurane Sevoflurane Desflurane

Question 51

When should you use caution with inhalation agents?

Answer 51

With stressed animals due to high epinephrine levels

Question 52

What is chamber induction used for?

Answer 52

Small animals/exotics | Small, really upset animals

Question 53

What is the oxygen flow rate like in chamber induction?

Answer 53

High

Question 54

What is the inhalant concentration like in chamber induction?

Answer 54

High

Question 55

What is mask induction used for?

Answer 55

Pocket pets, birds/exotics, neonates, and pediatrics

Question 56

What do you do after anesthetic induction?

Answer 56

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