Induction Agents Flashcards
induction agent
chemical agent that allows intubation which bridges the gap between premed and inhalant anesthetics
4 Most Commonly Seen Induction Agents in Veterinary Practice
- Propofol
- Alfaxalone
- Etomidate
- Ketamine
Two Possible MOAs for Induction Agents
- GABAa agonist
- NMDA antagonist
What’s the right propofol dose?
titrate to effect
Can you give Propoflo28 to cats?
Only once! Cats cannot metabolize the benzyl alcohol preservative that is added to increase shelf life.
main inhibitory NT of the CNS
GABA
main excitatory NT of the CNS
NMDA (glutamate)
Which of the four main induction agents is an NMDA antagonist?
ketamine
Onset and Duration of Propofol
fast onset, short duration
CNS Effects of Propofol
hypnosis, decreased ICP and blood flow, decreased oxygen demand
Respiratory Effects of Propofol
depressant (speed and dose dependent)
CV Effect of Propofol
depressant
inotrope
drug that affects contractility of the heart
Does propofol cause hypo or hypertension?
hypotension (transient and dose-dependent, goes away when drug wears off)
Is propofol a positive or negative inotrope?
negative
Is propofol safe for c-sections?
yes
Why is propofol not good for cats?
can cause RBC lysis/Heinz body anemia with repeated administrations
Main excretion of propofol?
liver
What drug is known as “clear propofol?”
Alfaxalone
Can cats have alfaxalone?
yes! Better than propofol because no RBC lysis
Can alfaxalone be given IM?
yes
Onset and Duration of Alfaxalone
fast onset, short duration
Do you see alfaxalone side effects if given IM?
not so much
Effects of Propofol and Alfaxalone on Intraocular Pressure
Propofol will decrease IOP, Alfax will increase IOP
Etomidate Onset and Duration
fast onset, short duration
Etomidate effect on Cardiovascular System
NONE/MINIMAL, good for heart failure, stenosis, etc
Why is etomidate not used more if it’s so much better for the cardiovascular system?
absolutely must be given with a co-induction agent, can cause stiffness, retching/vomiting, pain on injection, and adrenocortical suppression
so overall induction quality is poor
NMDA Antagonist
prevents uptake of calcium
Cyclohexanes
dissociative anesthetic agents which include ketamine, tiletamine and zolazepam (Telazol)
What two induction agents must only be given IV?
propofol and etomidate
Routes of Administration of Ketamine
IV, IM, buccal
Can ketamine be given alone?
technically yes but it needs a VERY strong premed, otherwise the animal will be too stiff (muscle rigidity)
Which induction agent is a CNS stimulant?
ketamine!
CNS Effects of Ketamine
dissociation, INCREASED ICP, blood flow, and oxygen demand
Respiratory Effects of Ketamine
bronchodilator! (not so much of a depressant comparatively)
Can you give cats with HCM ketamine?
NO
Overall Cardiovascular Effect of Ketamine
INCREASE because the catecholamine surge from adrenal stimulation overrides the negative inotropic effect
Which two agents are safe for c-sections?
propofol and alfaxalone
Nystagmus is a side effect of which induction agent?
ketamine (increased IOP)
Tiletamine
cyclohexane which is slower to be metabolized than ketamine so it lasts longer (but can be nephrotoxic in rabbits)
Benzodiazepines
muscle relaxing agents for co-induction
midazolam (water soluble) and diazepam (lipid soluble)
Lidocaine
co-induction agent good for analgesia, antiarrhythmic (VPCs), and MAC reductive
Main Induction agent in horses?
ketamine, +/- guaifenesin
