Lecture 4 8/28/24

Question 1

What is the goal of anesthetic induction?

Answer 1

transition from a state of consciousness to unconsciousness while minimizing undesirable effects

Question 2

What are the benefits of injectable induction?

Answer 2

-smooth transition
-no waste gas

Question 3

What is the disadvantage of injectable induction?

Answer 3

cannot be immediately controlled or eliminated once administered

Question 4

What are the two main ways that injectable induction agents work?

Answer 4

-GABA binds to receptor, allowing Cl- to enter and hyperpolarize cell to inactivate it
-glutamate is inhibited so that sodium cannot enter the cell, preventing an action potential

Question 5

What are the primary uses of benzodiazepines?

Answer 5

-sedation
-amnesia
-muscle relaxation

Question 6

Which drugs fall into the benzodiazepines category?

Answer 6

-midazolam
-diazepam
-zolazepam

Question 7

What are the characteristics of midazolam?

Answer 7

-water soluble
-can be given IM, SQ, IV
-mixes well with other drugs
-does not adhere to syringe
-does not cause precipitants

Question 8

What are the characteristics of diazepam?

Answer 8

-lipid soluble
-given IV only
-mixes only with ketamine

Question 9

What are the CNS effects caused by benzodiazepines?

Answer 9

-decreased cerebral metabolic rate
-decreased cerebral blood flow
-decreased intracranial pressure
-anti-convulsant
-mild, patient-dependent sedation

Question 10

What are the cardiovascular and respiratory effects caused by benzodiazepines?

Answer 10

minimal CV and resp. effects

Question 11

What are the GI effects caused by benzos?

Answer 11

-appetite stimulant in cats
-causes hepatic failure after PO admin. in cats

Question 12

In which patients are benzos a good pre-medication selection?

Answer 12

-debilitated small animals and small ruminants (ASA 3-5)
-neonates
-geriatrics

Question 13

Why are benzos only used along with a dissociative drug for induction in healthy adult patients?

Answer 13

they lead to excitement when used alone

Question 14

What is the mechanism of action for propofol?

Answer 14

potentiates GABA

Question 15

What is the main use of propofol?

Answer 15

-rapid, smooth induction
-unconsciousness
-immobility
-muscle relaxation

Question 16

What are the characteristics of propofol?

Answer 16

-formulated in lipid emulsion
-not shelf stable
-used for CRIs; do not want the side effects of the preservative in the shelf stable version

Question 17

What are the characteristics of propofol 28?

Answer 17

-stable for 28 days
-benzyl alcohol preservative

Question 18

What are the physiologic characteristics of propofol?

Answer 18

-short duration of action
-must be given IV
-narrow therapeutic index/possible to overdose
-mainly hepatic metabolism
-extra-hepatic metabolism possible, allowing for safe use in patients with liver failure

Question 19

What are the CNS effects associated with propofol?

Answer 19

-decreased cerebral metabolic rate
-decreased cerebral blood flow
-anti-convulsant
-decreased intracranial and intraocular pressures

Question 20

What are the resp. effects associated with propofol?

Answer 20

-resp. depression
-apnea

Question 21

What measures should be taken to ensure proper resp. support when using propofol?

Answer 21

-pre-oxygenate
-avoid use if intubation and ventilation is not feasible

Question 22

What are the cardiovascular effects associated with propofol?

Answer 22

vasodilation and hypotension with no compensatory increase in heart rate

Question 23

What are the other potential effects of propofol?

Answer 23

-occasional pain on injection
-rapidly metabolized by fetus
-heinz body anemia and hemolysis in cats
-vomiting in cats

Question 24

What are the clinical uses of propofol?

Answer 24

-induction of anesthesia
-partial intravenous anesthesia
-total intravenous anesthesia

Question 25

What is the mechanism of action for alfaxalone?

Answer 25

GABA agonist

Question 26

What is the main use of alfaxalone?

Answer 26

-unconsciousness -immobility -muscle relaxation

Question 27

What are the physiologic characteristics of alfaxalone?

Answer 27

-IV or IM administration -rapid induction -short duration around 10 minutes -hepatic metabolism

Question 28

What are the CNS effects associated with alfaxalone?

Answer 28

-decreased cerebral metabolic rate -decreased cerebral blood flow -decreased intracranial and intraocular pressures -myoclonus

Question 29

What are the cardiovascular effects associated with alfaxalone?

Answer 29

dose-dependent vasodilation and decreased contractility in sick patients

Question 30

What are the respiratory effects associated with alfaxalone?

Answer 30

dose-dependent apnea and cyanosis

Question 31

What are the clinical uses of alfaxalone?

Answer 31

-IM sedation -induction of anesthesia -PIVA -TIVA

Question 32

What is the mechanism of action for etomidate?

Answer 32

potentiates GABA

Question 33

What are the main uses of etomidate?

Answer 33

-unconsciousness -immobility

Question 34

Why must etomidate be combined with a benzo?

Answer 34

because etomidate does not induce adequate muscle relaxation

Question 35

Why is it important that etomidate is formulated in propylene glycol?

Answer 35

-causes pain on injection -can cause hemolysis with large doses or if used for infusion

Question 36

What are the physiologic characteristics of etomidate?

Answer 36

-IV admin. only -rapid and rough induction -short duration

Question 37

What are the resp. effects associated with etomidate?

Answer 37

resp. depression and possible apnea

Question 38

Why is etomidate useful?

Answer 38

it has nearly no cardiovascular effects and is therefore safe for patients with CV disease

Question 39

What are the CNS effects associated with etomidate?

Answer 39

-decreased cerebral metabolic oxygen rate -decreased cerebral blood flow -decreased intracranial pressure -myoclonus possible

Question 40

Why is it important that etomidate causes immunosuppression and decreased cortisol production?

Answer 40

-should not be used for CRIs or repeat injections -should be avoided in Addison's patients

Question 41

What are the characteristics of etomidate clinical use?

Answer 41

-for use in patients with clinically significant cardiac disease -not for routine patients -not for CRIs -combined with a benzo to provide muscle relaxation and smoother induction

Question 42

Which drugs fall into the dissociative category?

Answer 42

-PCP derivatives -ketamine -tiletamine formulated with zolazepam (telazol)

Question 43

Why are dissociatives combined with benzos?

Answer 43

dissociatives do not achieve muscle relaxation on their own

Question 43

What is the main use of dissociatives?

Answer 43

-dissociation of thalamus and limbic system to produce a cataleptoid state -unconsciousness -analgesia

Question 44

What is the mechanism of action for dissociatives?

Answer 44

NMDA antagonist

Question 45

What are the characteristics of dissociative use for analgesia?

Answer 45

-work through NMDA antagonism and opioid receptor interactions -adjunct agent as a CRI -causes hyperalgesia good for chronic pain and neuropathic pain

Question 46

How can dissociatives be administered?

Answer 46

-IV -IM -SQ -OTM

Question 47

What are the CV effects associated with dissociatives?

Answer 47

-increased sympathetic output -tachycardia -hypertension -increased cardiac output

Question 48

Which cardiac disease patients should not receive dissociatives?

Answer 48

those with hypertrophic cardiomyopathy

Question 49

What are the resp. effects associated with dissociatives?

Answer 49

-apneustic breathing/inhaling and holding breath -bronchodilation -laryngeal reflexes maintained

Question 50

What are the CNS effects associated with dissociatives?

Answer 50

-increased cerebral metabolic rate -increased cerebral blood flow -increased intracranial pressure

Question 51

What are the clinical uses of ketamine?

Answer 51

-IM for heavy sedation/immobilization -induction of anesthesia -PIVA -TIVA

Question 52

What are the characteristics of telazol clinical use?

Answer 52

-duration of action around 30 minutes -expensive but used in small volumes -used in fractious animals/zoo animals

Question 53

What is the use of guafenesin?

Answer 53

disrupts nerve impulse transmission in the CNS to cause muscle relaxation

Question 54

What are the adverse effects of guafenesin?

Answer 54

-hypotension -resp. depression -necrosis if administered peri-vascularly -thrombophlebitis

Question 55

What are the clinical uses of guafenesin?

Answer 55

-equine induction -TIVA and PIVA