Case series (Gatson) Flashcards
Hyperthyroidism can be controlled with
Methimazole
Physiologic concerns geriatric patients
Dogs & Cats > 12 years old => 7 fold inc risk morbidity/mortality related to anesthesia
Decreased physiologic reserve of organ systems
Exaggerated response to drugs
- Dec albumin
- Dec skeletal m. Inc fat
- Reduced total plasma volume (loss of totaly body water)
Prolonged duration of action renally/hepatically excreted drugs
Painful pre-existing conditions (osteoarthritis)
Cats
Glucoronidation
Alteration in Phase 2 Hepatic Enzymes
Cats
Differences in drug metabolism
Differences in drug metabolism - phenolic compounds
- propofol => Heinz body anemia with repeated doses
- Acetaminophen => highly toxic in cats
Cats and opioids
Can cause hyperthermia during anesthesia
Opioid mania - high doses
- Pupillary dilation
- dysphoria
Less MAC reduction with opioids compared to dogs
Cats and sedatives
Ace: sedation in dogs >>cats
Benzodiazepines
- cause excitement in cats
Cats and obesity
Cats > 6kg are 3 X more likely to die perianesthetically
Dose at lean body weight, and titrate to effect
Vomiting and Nausea
Opioids
Greatest:
- Morphine
- Hydromorphone
- Oxymorphone
- Meperidine
- Apomorphine (IM)
Least:
- Methadone
- Buprenorphine
- Butorphanol
Vomiting and Nausea
Alpha-2 Agonists
Xylazine
Dexmeditomidine
Acepromazine
Anti-emetic (cats only?)
Phenothiazine Tranquilizer
- Antagonist:
- Dopamine (low dose)
- Serotonin Receptors (low dose)
- Anticholinergic
- Emetic Center (high dose)
Cerenia
Neurokinin - 1 receptor antagonist
Higher Centers
Vomiting and Nausea
Psychogenic
Trauma
Intracrania
Pressure
Vestibular Apparatus
Vomiting and Nausea
Motion Sickness
Emetic Center
Vomiting and Nausea
CTZ
- Blood-borne
- Drugs
- Toxins
Peripheral Receptors
Vomiting and Nausea
Abdominal and thoracic organs
Irritation
Ace vs cerenia as a premed
Ace
- 30-50% reduction in vx if given 20 min before morphine or hydro
Cerenia
- 70-100% reduction in vx if given 20-45 min before morphine or hydro
Hyperthyroidism concerns
Cardiovascular
Cardiomyopathy
- reduced stroke volume
- reduced CO
Hypertension
Tachycardia
Arrhythmias
Inc myocardial O2 consumption
Drugs to avoid with hyperthyroidism
Drugs that cause
- tachycardia
- inc myocardial O2 consumption
No ketamine
No anticholinergics
avoid stress
consider subclinical HCM
Ideal PREMED
Short acting/reversable
Does not cause vx
Does not bind heavily to plasma proteins
Causes minimal changes to cardiovascular system
Allows easy passage of endoscope into SI
Acts on visceral pain
Sugar Daddy anesthetic plan
12 y/o MC DSH
Vomiting past 2 months
Anorexic and lethargic for 1 week
Hyperthyroidism: controlled with methimazole
Anesthetic plan
Premed: Methadone + Maropitant
Induction: Alfaxalone
Maintenance: Sevoflurane
Intra-op / Post-op: Methadone
Major functions of the Liver
1.
2.
3.
4.
5.
6.
7.
- Nutrient storage and supply
- fat
- carbs
- protein metabolism
- Protein homeostasis
- albumin => oncotic pressure
- clotting factors
- Biotransformation
- Biliary excretion
- Removal of ammonia
- Urea production
- Host defense from bacteria / toxins from portal circulation
Characteristics of ideal drugs for liver disease
1.
2.
3.
4.
- Doesn’t depend on liver for metabolism
- Doesn’t alter hepatic blood flow
- Has minimal protein binding
- Is reversible
Neuromuscular Blocking Agents
w/ Extra-hepatic Metabolism
Atracurium (Ester hydrolysis and/or Hofman elimination)
Succinylcholine (Plasma Cholinesterases…but made by liver)
Opioids
w/ Extra-hepatic Metabolism
Remifentanil (Plasma esterases)
Fentanyl, Alfentanil, Sufentanil (liver + plasma esterases)
Inhalants
w/ Extra-hepatic Metabolism
Don’t rely on liver/kidneys
Desflurane (least liver metabolism) > Isoflurane > Sevoflurane
Isoflurane: least effect on hepatic blood flow (think)
Drug reversals
- Dexmeditomidine:
- Hydromorphone:
- Butorphanol:
- Midazolam:
- Acepromazine:
- Dexmeditomidine: Atipamazole
- Hydromorphone: Naloxone
- Butorphanol: Naloxone
- Midazolam: Flumazenil
- Ace: Nada
Jack Perro: Anesthetic plan
5 y/o MC Labrador
Previously completely healthy
Acute history of vomiting, lethargy, inappetence
Owners noticed yellowed eyes and gums
Lives on 5 acres, runs around unsupervised
Anesthetic Plan
Premedication: Methadone
Induction: Propofol
Maintenance: Isoflurane
Intra-op / Post-op: Remifentanil
Jack Perro
Additional concerns
Maintain blood glucose w/in reference range
Test clotting factors (may need plasma)
Avoid NSAIDS
Benzodiazepines, Phenothiazines, Opioids
- Prolonged duration of action
Mast Cell Tumors
Signs under general anesthesia
Treatment
Signs
- redness of skin
- hives
- hypotension
- reflex tachycardia
TX
- Crstalloid fluid bolus
- Epinephrine
ABCB1 Mutation
(formerly MDR-1)
Codes for p-glycoprotein and multi-drug resistent-related protein
Significantly affects drug distribution / elimination
- mutant allele can cause excessive drug conc into brain
Drugs that use p-glycoprotein
- macrocyclic lactones (ivermectin, milbemycin)
- chemotherapeutic agents
- loperamide
- ace
- butorphanol
- morphine
- ondansetron
Schmidty Anesthetic Plan
9 y/o Female Collie
Breeding award-winning show dog
Mass on front right digit (possible mast cell tum)
Normal physical exam and bloodwork from RDVM
Owners interested in surgical removal
Surgery requests CT of thorax and right front limb to rule out metastatic dz
Anesthetic Plan
Premedication: Benadryl + Dexmeditomidine + low dose Butorphanol
Induction: Propofol
Maintenance: Isoflurane
Intra-op / Post - op: nothing
Consider reversing
Dalek Anesthetic Plan
15 y/o Quaterhorse mare
Non-healing corneal ulcer
Fungal keratitis
Many ophthalmic meds +
- Fluconazole
- TMS
- Banamine
- Gastrogard
Keratectomy OS
Anesthetic Plan
Premedication: Xylazine + Butorphanol
Induction: Ketamine + Propofol
Maintenance: Isoflurane
Intra-op / Post-op: Xylazine
Drugs that induce liver metabolism
Phenobarb induces cytochrome P450 liver enzymes
- faster drug metabolism
- shortened pharmacologic action
Drugs that inhibit liver metabolism
Fluconazole inhibits CYP3A4
- This enzyme metabolizes many anesthetic agents
- midazolam
Things that inc IOP
Intubation
Head Extension
Occluding jugulars
Hypercapnia
Hypoxemia
Drugs:
- Ketamine
- Propofol (dogs)
- Etomidate
- Succinylcholine
Things that decrease IOP
Hypocapnia
Drugs:
- Ketamine?
- Barbiturates
- Propofol (horses)
- Alpha-2 Agonists
- Benzos
- Opioids
- Inhalants
- Nondepolarizing NMBA
Mr. Wiggelsworth Anesthetic Plan
3 y/o MC Husky
Completely torn left cranial cruciate ligament
No medications
Normal BW
Aggressive
Anesthetic Plan
Premedication: Dexmeditomidine + Hydromorphone
Induction: Ketamine + Diazepam
Maintenance: Sevoflurane
Intra-op / Post-op: LS Epidural (Morphine + Bupivacaine) + Post-op carprofen
