Lecture 9 Anesthesia in Dogs and Cats Part 1 Flashcards
What can be done to Prevention of Peri-anesthetic nausea & vomiting
- Give Maropitant (Cerenia) – Neurokinin-1 antagonist 1.0mg/kg subQ at least one hour before opioid premedication
- Prevents vomiting & signs of nausea associated with opioid drugs
- Faster return to feeding PO
What type of drug is Maropitant (Cerenia)
•Neurokinin-1 antagonist
Other than preventing vomiting and nausea, what does Maropitant (Cerenia) do?
Adjunct analgesia - ↓MAC sevoflurane in dogs & cats
- What do opoids do to the body
- MAC?
- Bradycardia, respiratory depression
- Mild CV effects
- ↓ MAC of inhalant
What are some considerations when choosing an opioid?
- Pre-emptive pain score – None, mild, moderate, severe pain
- Duration of action – (Onset of action – buprenorphine)
- Ceiling effect?
- Does it cause nausea/vomiting?
- ↑ IOP, ICP, risk for aspiration => brachycephalic, laryngeal hemiplegia, neurologic patients
- Route of administration – fentanyl requires IV catheter
- MAC sparing
- Dog vs cat – mu agonists
- What type of drug is butorphanol
- Does it cause sedation?
- if so how long does it last?
- Analgesia?
- if so how long does it last?
- Kappa agonist-mu antagonist
- Mild sedation
- 1-2 hours,
- Mild analgesia
- ~90min.
- Does butorphanol have a ceiling effect?
- What type of procedures is it used on?
- ‘Ceiling effect’
- Non- or mildly painful procedures
- Imaging, minor sx procedure
- Pre-med to avoid vomiting, full agonist to follow
- What type of drug is buprenorphine
- Causes sedation?
- Analgesia?
- Partial mu agonist
- Little sedation,
- mild-moderate analgesia
- Can Buprenorphine be easy to reverse?
- onset
- duration
- Does it have a ceiling effect?
- Very ‘sticky’ to mu receptor
- difficult to reverse or to follow with mu agonist
- Slow onset => 30-45min.
- Duration => Dogs: 4-10 hours, Cats: 6-12 hours
- ‘Ceiling effect’
What are the full mu agonists
- Hydromorphone,
- Morphine,
- Oxymorphone,
- Methadone
- How much pain do the full mu agonists alieve
- Duration of actions for each?
- Moderate – severe pain
- Duration of action:
- Hydro/oxymorphone: 2-4 hours
- Morphine, Methadone 4-6 hours
Which full mu agonist is also an NMDA antagonist
Methadone
What are the side effects of full mu agonists
- –Nausea, Vomiting, defecation
- –Dysphoria, Panting
- –CV effects minimal; bradycardia
- –Respiratory depression
- –Hyperthermia in cats
- –Morphine can cause histamine release if given quickly IV
- What type of drug is fentanyl
- How much pain does it alleviate?
- Duration of action?
- What does it to do MAC of ISO?
- Full mu agonist
- Moderate-severe pain
- Short acting; 20-30 min.,
- requires IV catheter/CRI
- ↓ MAC of ISO ~65%
- What is a side effect that most full mu agonists that fentanyl doesnt have
- What are its cardiovascular effects?
- Respiratory effects?
- •No vomiting, no histamine release
- •Mild CV effects -> Bradycardia
- •Respiratory depression -> Monitor SpO2, IPPV
What 2 drugs can be used as an induction agent IV in critical ill patients
- Fentanyl
- Midazolam
What are the Premedications that are sedatives
- Acepromazine
- Dexmedetomidine/Medetomidine
- Midazolam
- Diazepam
- What type of drug is Acepromazine
- Duration of action?
- Does it have a reversal agent. If so what?
- Phenothiazine, alpha-1 antagonist
- Long duration of action 4-6 hours (will last thorough recovery)
- No reversal agent
- Does acepromazine cause sedation?
- Analgesia?
- –Relatively more mild sedation vs dexmedetomidine
- –No analgesic effects, synergistic effect with opioids
- What are the cardiovascular effects of acepromazine?
- Which types of animals do you want to give a low dose/ avoid it in?
- What conditions do you avoid it in?
- Vasodilation, hypotension,bradycardia
- Lower dose/ avoid IV,
- geriatric,
- pediatric,
- liver dysfunction
- Avoid in:
- hypovolemia,
- shock,
- critically ill,
- liver failure
- Does Dexmedetomidine cause sedation?
- Analgesia?
- Onset of action?
- Duration of action?
- Potent sedative
- analgesia
- Short onset of action (~5-10 minutes)
- Short duration of action (may not last throrough recovery)
- May need sedation for recovery to avoid sudden arousal
- What are the cardiovascular effects of Dexmedetomidine
- What is the reversal agent?
- What type of patients do you use it in?
- 40% ↓ CO, reflex bradycardia due to vasoconstriction
- Atipamazole
- Reserve for healthy or very painful, fearful, aggressive patient
- Midazolam is good to use in young, healthy dogs?
- Geriatric, critical patients?
- What are its cardiovascular effects?
- Typically NOT good sedative in young, healthy dogs
- Paradoxical excitement
- effective in geriatric, critical patients
- Mild cardiovascular effects
- What are midazolams uses?
- Does it cause amnesia?
- Uses:
- Induction adjunct => ↓ Propofol induction dose
- Anti-convulsant => seizure patients
- Amnesic
- What are the 2 anti-cholinergics?
- What does it do to vagal effects
- Salivary secretions?
- Atropine and Glycopyrrolate
- ↓ vagal effects
- ↓ salivary secretions
- Does atropine cross BBB/placenta?
- Onset of action
- Duration of action?
- Crosses BBB/placenta
- Onset of action (minutes): 5 IM, 1 IV
- DOA: 60-90 minutes
- Does Glycopyrrolate cross BBB/placenta?
- Onset of action
- Duration of action?
- –Does not cross BBB/placenta
- –Onset of action: 3 – 5 minutes
- –DOA: 2-4 hours
- Side effects of Anti-cholinergics
- What drug and when is it contraindicated?
- Side effects: sinus tachycardia, 2° A-V block
- Do NOT use with Dexmedetomidine if high BP
•Should you use an anti-cholinergic in premedication?
- Easier to prevent bradycardia than to treat it
- IV anti-cholinergics can cause arrhythmias (see above)
- Pediatric patients
- More dependent on HR for CO
- Brachycephalic breeds – high vagal tone with upper airway obstruction
Which disease process do you avoid anti-cholinergics in?
–Avoid in patients with cardiac disease
Give a brief summery of the preanesthetics and what they are based on and indicated/ contraindicated in
- Opioid Analgesic- Butorphanol, buprenorphine, full mu agonist (or fentanyl IV)
- Based on pre-emptive pain score, inhalant sparing needs, cost, availability
- +/- Sedative – Acepromazine, Dexmedetomidine, Midazolam
- Based on signalment, temperment, patient physical status, co-morbidities
- +/- Anti-cholinergic
- Indications: Pediatric, brachycephalic
- Contraindications: cardiac disease
What are some reasons why cats are NOT small dogs
- Restraint/Catitude
- Combination vs single drug sedation
- Airway issues
- Laryngospasm
- Tracheal rupture
- Drug Metabolism
- Pain Evaluation
What are the drug combinations for ‘Kitty Magic’
- Dexmedetomidine
- Opoid
- Butorphanol
- Buprenorphine
- Methadone
- Hydromorphone
- Ketamine or tealazol if need more restraint (evil cat)
- ↑ restraint (aggressive patients)
- analgesia
- total injectable anesthesia
What are the benefits of using dexmedetomidine in “kitty magic”
- Provides sedation & analgesia
- Quick onset of action (5-10 minutes)
- Relatively short duration of action 0.5 – 1.0 hr depending on dose/route
- Reversible
What are the opioids used in “kitty magic”
- Butorphanol
- Buprenorphine
- Methadone
- Hydromorphone
Benefits of using butorphanol in kitty magic
- short acting ~90 minutes
- ceiling effect’ =>↑ dose, no additional analgesia
- Better sedation than Buprenorphine
Benefits of using Buprenorphine in kitty magic
- Slow onset of action => 30-45 minutes**
- Duration of action => 6-12 hours in cats
- Very ‘sticky’ to mu receptor, difficult to reverse
- Moderate analgesia, sedation < butorphanol
- What are side effects of Buprenorphine
- What is another mode of administration other than IV,SQ,IM
- Does it cause hyperthermia in cats?
- Vomiting, dysphoria RARE
- Good bioavailability with oral transmucosal dosing
- NOT ASSOCIATED with hyperthermia in cats**
- What are the benefits of using buprenorphine alone with dexmedetomidine
- Butorphanol pre-med, give Buprenorphine 1 hour later?
- Give both Butorphanol, Buprenorphine with Dexmedetomidine pre-med?
- Buprenorphine (alone) with Dexmedetomidine
- Less sedation, delayed onset of analgesia
- OK if using Ketamine
- Butorphanol pre-med, give Buprenorphine 1 hour later
- Better initial sedation, longer lasting analgesia
- Give both Butorphanol, Buprenorphine with Dexmedetomidine pre-med
- One administration, but larger volume
- Opioid interference?
- Mu-antagonist + partial mu agonist
- What type of drug is Methadone
- Mode of administration
- Mu-agonist, NMDA-receptor antagonist
- IM, IV, SC
- How much pain does Methadone releave
- Is there a ceiling effect
- Duration of action?
- What effect does it have on cats?
- Moderate to severe pain
- No ceiling effect
- Duration of action ~4 hours
- Euphoria in cats
- What type of drug is Hydromorphone/Morphine
- What happens if you give morphine IV rapidly?
- mu-agonists
- Morphine- histamine release if given rapidly IV
Hydromorphone has been with associated with what side effect in cats?
- hyperthermia
- 75% cats had rectal temp >104, peak temp 108.5
- Related to severity of intra-op hypothermia
When and why would you add ketamine or telazol to kitty magic
- More profound/reliable restraint, add 2-3 mg/kg
- if aggressive
- ‘Excited’ cats may ‘over-ride’ Dexmedetomidine sedation
- Additional Dexmeditomidine does NOT ↑ level of sedation
- Add 2 - 5mg/kg if cat is ‘resistant’
- Less ↓ in HR
How long does Ketamine (or Telazol) last in cats?
30 – 40 minutes
Give some ‘Kitty Magic’ Options
- Dexmedetomidine + Butorphanol
- Short acting sedation, mild analgesia
- Give buprenorphine 1 hour after butorphanol for longer, moderate analgesia
- Still need induction agent
- Dexmedetomidine + Ketamine (or Telazol) + Buprenorphine
- D & K provide initial analgesia before slow onset of analgesia by buprenorphine (~45 minutes)
- Dexmedetomidine + Methadone
- Moderate-severe pain
- Add Ketamine or Telazol to any for ↑ restraint or TIA
- Which ‘kitty magic’ drug causes salivation?
- Which ‘kitty magic’ drug decreases salivation?
- Ketamine based protocols require anti-cholinergic to ↓ salivation
- Dexmedetomidine is an antisialogue so anti-cholinergic not needed if given with Ketamine