13/14: Anesthesia in Dogs & Cats Flashcards
What is a common way to prevent peri-anesthetic nausea and vomiting?
Maropitant - 1.0 mg/kg 1 hour before opioid administration
When is injectable maropitant given to cats?
20 hours prior to dexmetetomidine + morphine
What is the result of giving cats injectable maropitant pre-op?
Significant decrease in vomiting, no significant decrease in nausea
When is oral maropitant given to cats pre-op?
2-18 hours prior to dexmedetomidine + morphine
What is the result of giving cats oral maropitant pre-op?
Significant decrease in vomiting but not signs of nausea
When are dogs treated with maropitant pre-op?
45 min prior to morphine
When do dogs return to normal feeding PO if treated with maropitant?
20 hours
What is the consumption difference in dogs pre-tx with cerenia vs those that are not?
Pre-tx = higher mean total food consumption (4.85x more food)
T/F: Owners generally do not worry that their pets will have nausea and vomiting related to surgery
False
What % of owners would probably or definitely choose treatment for nausea? Vomiting?
Nausea = 95.7%
Vomiting = 99%
What % of owners were likely to accept nausea/vomiting treatment for their pets if veterinarian recommended?
95%
Generally, what effects do opioids have on CV, MAC, and respiration?
Mild CV effects, decreased MAC, bradycardia, resp depression
What type of drug is butorphanol?
K agonist/Mu antagonist
Does butorphanol provide sedation/analgesia?
Yes, mild to both
How long does sedation from butorphanol last?
1-2 hours
How long does analgesia from butorphanol last?
~90 min
Does butorphanol have a ceiling effect?
Yes
What is butorphanol used for?
Non or mildly painful procedures
What type of drug is buprenorphine?
Partial mu agonist
Does buprenorphine provide sedation/analgesia?
Yes: little sedation, mild to moderate analgesia
What does it mean when we say that buprenorphine is “sticky” to the mu receptor?
It is difficult to reverse or to follow with a mu agonist
What is the onset of buprenorphine? Duration?
Onset = 30-45 min (slow)
Duration = 4-10 hours in dogs, 6-12 hours in cats
Does buprenorphine have a ceiling effect?
yes
What are the full mu agonists?
Hydromorphone, Morphine, Oxymorphone, Methodone, Fentanyl
What type of pain are full mu agonists used for?
moderate to severe
What is the duration of action of hydro/oxymorphone?
2-4 hours
What is the duration of action of morphine/methadone?
4-6 hours
What is the duration of fentanyl?
20-30 min
What does fentanyl require for administration?
IVC/CRI
What does fentanyl do to the MAC of iso?
Decreases it by ~65%
What side effect does fentanyl not have compared to the other mu agonists?
vomiting
What is the main CV effect that fentanyl has?
Bradycardia
What type of drug is acepromazine?
Phenothiazine, alpha-1 antagonist
What is the duration of action of ace?
4-6 hours
Does ace have a reversal agent?
No
What CV effects does ace have?
Vasodilation, hypotension, bradycardia
What is the onset of dexmedetomidine?
Short = ~5-10 minutes
What is the duration of dexmedetomidine?
Short
What are the CV effects of dexmedetomidine?
40% decrease in CO, reflex bradycardia due to vasoconstriction
Does dexmedetomidine have a reversal?
Yes - atipamazole (Antisedan)
When should midazolam not be used as a sedative?
Young, healthy dogs
What are the CV effects of midazolam?
Mild
What is midazolam used as an adjunct with?
propofol
What can midazolam be used to treat?
seizures
Which anti-cholinergic crosses the BBB/placenta?
atropine
What is the onset of action of atropine?
5 min IM
1 min IV
What is the duration of atropine?
60-90 min
What is the onset of glycopyrrolate?
3-5 min
What is the duration of glycopyrrolate?
2-4 hours
What are CV side effects of anti-cholinergics?
Sinus tachycardia, 2nd deg AV block
What drug should anti-cholinergics NOT be used with if the patient has high BP?
dexmedetomidine
What airway issues are common in cats?
Laryngospasm, tracheal rupture
What is the anesthetic protocol for premeds in cats?
Sedative (usually dexmedetomidine) + an analgesic (opioid)
In addition to a sedative + analgesic, what can be added to cats for “kitty magic”?
Ketamine or telazol
What cat patients is use of ketamine or telazol contraindicated in? What can be used instead?
Hypertrophic cardiomyopathy;
Can use alfaxalone instead of ketamine
T/F: Alfaxalone + butorphanol does not affect ECG parameters in healthy cats
True
What does “kitty magic” start with?
Dexmedetomidine
What is used in “kitty magic” for analgesia?
Opioid (Butorphanol, buprenorphine, methadone, hydromorphone, morphine)
What type of dosing does buprenorphine have good bioavailability with?
oral transmucosal
Timing wise, what happens if buprenorphine is given alone with dexmedetomidine?
Less sedation and delayed onset of analgesia
What should be done to bridge the time gap of opioids in kitty magic?
Butorphanol pre-med, then give buprenorphine 1 hour later (butorphanol will kick in quickly, then once it wears off buprenorphine kicks in ~1 hour later)
What is a good substitute for buprenorphine to use in kitty magic if you need a full mu agonist?
methadone
What does methadone cause in cats?
euphoria
How can methadone be administered?
transmucosally
What unwanted effect can hydromorphone have in cats?
Hyperthermia
What drugs can be added for difficult cats to produce total injectable anesthesia?
Ketamine or Telazol
What are 3 examples of “kitty magic” options?
- Dexmedetomidine + Butorphanol
- Dexmedetomidine + Ketamine (or Telazol) + Buprenorphine
- Dexmedetomidine + Methadone
What kind of procedures would call for use of dexmedetomidine + methadone in cats?
More extensive procedures in cats with moderate to severe pain
When using dexmedetomidine + butorphanol, what must be given 1 hour later?
buprenorphine
Ketamine based protocols require _____ to decrease salivation.
anti-cholinergic
What are 2 general functions of drug metabolism?
- Conversion of pro-drug to active form
- Metabolism of drugs to inactive, more water-soluble form for excretion
What are phase I reactions of drug metabolism?
Oxidation (CYP450) reduction, hydrolysis
What are phase II reactions of drug metabolism?
Conjugation:
- Glucuronic acid
- Sulfate, glycine, glutamate, glutathione, acetylation, methylation
What mutation do cats have that impacts their drug metabolism?
Mutation in gene sequence for UGT1A6
What size ETT will most cats take?
4.5
How do you position a cat for intubation?
- Sternal recumbency, extend head/neck toward ceiling
- Thumb & forefinger behind canine teeth
- Tongue out of mouth between lower canines (straight out, not down!)
What can happen to the tongue during anesthesia?
Lingual edema - trauma from intubation, pulse ox probe, entrapped in ETT tie
What local anesthetic is placed on arytenoids of cats?
Lidocaine 0.1-0.2 mls 2% in syringe
How is local anesthetic used in intubation of cats?
- Position laryngoscope and visualize arytenoids
- Swab arytenoids with topical lidocaine on a Q-tip, then use another to go thru glottis and coat inside of the larynx
- Wait ~30 seconds
- Proceed with intubation
What local anesthetics cannot be used on arytenoids and why?
Cetacaine - methemoglobinemia (cats and sheep)
Zylocaine - risk of toxicity with multiple sprays in cats < 5 kg
What is the intubation technique?
- Blade of laryngoscope on tongue, under epiglottis, press down
- DO NOT touch epiglottis
- Direct tube to ventral aspect of glottis
- Rotate bevel of tube if arytenoids are closed
- Stylet if needed
What are likely causes for tracheal rupture?
Over-inflation of ETT, use of stylet, change of positioning without d/c from Y-piece
What drug mixture can be used in aggressive dogs?
Dexmedetomidine + Ketamine + Opioid (butorphanol)
What are disadvantages to using a boxing chamber and when should it be used?
- High doses needed
- Unable to monitor
- Waste gas pollution
- VERY stressful, increase SNS stim
- Thorough PE not possible
Use as a last resort
How should propofol be given IV?
1.0 mg/kg slowly over 30-60 seconds, then to effect for intubation
What are advantages to using propofol as an induction agent?
Smooth recoveries, not controlled, inexpensive
What is the benefit to giving alfaxalone over propofol?
Can be given IM
What are disadvantages to using alfaxalone as an induction agent?
Decreased recovery quality with high doses, controlled (Sched IV), more expensive
What is the benefit to using propofol and ketamine together?
They cancel out each other’s CV effects, better quality of induction/intubation
What is a proper induction protocol for critically ill patients (GDV, septic/hemoabd, severe heart dz)?
Opioid + BDZ (i.e. fentanyl + midazolam)
What is the MAC of iso in dogs? Cats?
Dogs = 1.3%
Cats = 1.6%
What is the MAC of sevo in dogs?
2.3%
What is a disadvantage to using sevo?
Expensive, toxic metabolites
What is the MAC of nitrous oxide in dogs?
~200%
What are benefits to using nitrous oxide?
Inexpensive, provides adjunct analgesia
What is MLK?
Morphine, Lidocaine, Ketamine
What is HLK?
Hydromorphone, Lidocaine, Ketamine
What is FLK?
Fentanyl, Lidocaine, Ketamine
Other than MLK, HLK, and FLK, what are some CRIs that can be used?
- Fentanyl
- Fentanyl + Ketamine
- Dexmedetomidine
- Dexmedetomidine + MLK
What drug classes inhibit pain perception?
Anesthetics, opioids, alpha-2 agonists, BDZ, phenothiazines
What drug classes inhibit pain transmission?
Local anesthetics and alpha-2 agonists
What drug classes modulate spinal pathways?
Local anesthetics, opioids, alpha-2 agonists, NSAIDs, NMDA antagonists, tricyclic antidepressants, anticonvulsants
What drug classes inhibit pain transduction?
NSAIDs, opioids, local anesthetics, corticosteroids
