Case series (Gatson)

Question 1

Hyperthyroidism can be controlled with

Answer 1

Methimazole

Question 2

Physiologic concerns geriatric patients

Answer 2

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)

Question 3

Cats

Glucoronidation

Answer 3

Alteration in Phase 2 Hepatic Enzymes

Question 4

Cats

Differences in drug metabolism

Answer 4

Differences in drug metabolism - phenolic compounds

• propofol => Heinz body anemia with repeated doses
• Acetaminophen => highly toxic in cats

Question 5

Cats and opioids

Answer 5

Can cause hyperthermia during anesthesia

Opioid mania - high doses

• Pupillary dilation
• dysphoria

Less MAC reduction with opioids compared to dogs

Question 6

Cats and sedatives

Answer 6

Ace: sedation in dogs >>cats

Benzodiazepines

• cause excitement in cats

Question 7

Cats and obesity

Answer 7

Cats > 6kg are 3 X more likely to die perianesthetically

Dose at lean body weight, and titrate to effect

Question 8

Vomiting and Nausea

Opioids

Answer 8

Greatest:

• Morphine
• Hydromorphone
• Oxymorphone
• Meperidine
• Apomorphine (IM)

Least:

• Methadone
• Buprenorphine
• Butorphanol

Question 9

Vomiting and Nausea

Alpha-2 Agonists

Answer 9

Xylazine

Dexmeditomidine

Question 10

Acepromazine

Answer 10

Anti-emetic (cats only?)

Phenothiazine Tranquilizer

• Antagonist:
  
  • Dopamine (low dose)
  • Serotonin Receptors (low dose)
• Anticholinergic
  
  • Emetic Center (high dose)

Question 11

Cerenia

Answer 11

Neurokinin - 1 receptor antagonist

Question 12

Higher Centers

Vomiting and Nausea

Answer 12

Psychogenic

Trauma

Intracrania

Pressure

Question 13

Vestibular Apparatus

Vomiting and Nausea

Answer 13

Motion Sickness

Question 14

Emetic Center

Vomiting and Nausea

Answer 14

CTZ

• Blood-borne
• Drugs
• Toxins

Question 15

Peripheral Receptors

Vomiting and Nausea

Answer 15

Abdominal and thoracic organs

Irritation

Question 16

Ace vs cerenia as a premed

Answer 16

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

Question 17

Hyperthyroidism concerns

Cardiovascular

Answer 17

Cardiomyopathy

• reduced stroke volume
• reduced CO

Hypertension

Tachycardia

Arrhythmias

Inc myocardial O2 consumption

Question 18

Drugs to avoid with hyperthyroidism

Answer 18

Drugs that cause

• tachycardia
• inc myocardial O2 consumption

No ketamine

No anticholinergics

avoid stress

consider subclinical HCM

Question 19

Ideal PREMED

Answer 19

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

Question 20

Sugar Daddy anesthetic plan

12 y/o MC DSH

Vomiting past 2 months

Anorexic and lethargic for 1 week

Hyperthyroidism: controlled with methimazole

Answer 20

Anesthetic plan

Premed: Methadone + Maropitant

Induction: Alfaxalone

Maintenance: Sevoflurane

Intra-op / Post-op: Methadone

Question 21

Major functions of the Liver

1.

2.

3.

4.

5.

6.

7.

Answer 21

1. Nutrient storage and supply

• fat
• carbs
• protein metabolism

2. Protein homeostasis

• albumin => oncotic pressure
• clotting factors

3. Biotransformation
4. Biliary excretion
5. Removal of ammonia
6. Urea production
7. Host defense from bacteria / toxins from portal circulation

Question 22

Characteristics of ideal drugs for liver disease

1.

2.

3.

4.

Answer 22

1. Doesn’t depend on liver for metabolism
2. Doesn’t alter hepatic blood flow
3. Has minimal protein binding
4. Is reversible

Question 23

Neuromuscular Blocking Agents

w/ Extra-hepatic Metabolism

Answer 23

Atracurium (Ester hydrolysis and/or Hofman elimination)

Succinylcholine (Plasma Cholinesterases…but made by liver)

Question 24

Opioids

w/ Extra-hepatic Metabolism

Answer 24

Remifentanil (Plasma esterases)

Fentanyl, Alfentanil, Sufentanil (liver + plasma esterases)

Question 25

Inhalants w/ Extra-hepatic Metabolism

Answer 25

Don't rely on liver/kidneys Desflurane (least liver metabolism) \> Isoflurane \> Sevoflurane **Isoflurane**: least effect on hepatic blood flow (think)

Question 26

Drug reversals ## Footnote 1. Dexmeditomidine: 2. Hydromorphone: 3. Butorphanol: 4. Midazolam: 5. Acepromazine:

Answer 26

1. Dexmeditomidine: Atipamazole 2. Hydromorphone: Naloxone 3. Butorphanol: Naloxone 4. Midazolam: Flumazenil 5. Ace: Nada

Question 27

Jack Perro: Anesthetic plan ## Footnote 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

Answer 27

Anesthetic Plan ## Footnote Premedication: Methadone Induction: Propofol Maintenance: Isoflurane Intra-op / Post-op: Remifentanil

Question 28

Jack Perro Additional concerns

Answer 28

Maintain blood glucose w/in reference range Test clotting factors (may need plasma) **Avoid NSAIDS** Benzodiazepines, Phenothiazines, Opioids * Prolonged duration of action

Question 29

Mast Cell Tumors Signs under general anesthesia Treatment

Answer 29

Signs * redness of skin * hives * hypotension * reflex tachycardia TX * Crstalloid fluid bolus * Epinephrine

Question 30

ABCB1 Mutation | (formerly MDR-1)

Answer 30

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

Question 31

Schmidty Anesthetic Plan ## Footnote 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

Answer 31

Anesthetic Plan ## Footnote Premedication: Benadryl + Dexmeditomidine + low dose Butorphanol Induction: Propofol Maintenance: Isoflurane Intra-op / Post - op: **nothing** **Consider reversing**

Question 32

Dalek Anesthetic Plan 15 y/o Quaterhorse mare Non-healing corneal ulcer Fungal keratitis Many ophthalmic meds + * Fluconazole * TMS * Banamine * Gastrogard Keratectomy OS

Answer 32

Anesthetic Plan ## Footnote Premedication: Xylazine + Butorphanol Induction: Ketamine + Propofol Maintenance: Isoflurane Intra-op / Post-op: Xylazine

Question 33

Drugs that induce liver metabolism

Answer 33

Phenobarb induces cytochrome P450 liver enzymes * faster drug metabolism * shortened pharmacologic action

Question 34

Drugs that inhibit liver metabolism

Answer 34

Fluconazole inhibits CYP3A4 * This enzyme metabolizes many anesthetic agents * midazolam

Question 35

Things that inc IOP

Answer 35

Intubation Head Extension Occluding jugulars Hypercapnia Hypoxemia Drugs: * Ketamine * Propofol (dogs) * Etomidate * Succinylcholine

Question 36

Things that decrease IOP

Answer 36

Hypocapnia Drugs: * Ketamine? * Barbiturates * Propofol (horses) * Alpha-2 Agonists * Benzos * Opioids * Inhalants * Nondepolarizing NMBA

Question 37

Mr. Wiggelsworth Anesthetic Plan ## Footnote 3 y/o MC Husky Completely torn left cranial cruciate ligament No medications Normal BW Aggressive

Answer 37

Anesthetic Plan ## Footnote Premedication: Dexmeditomidine + Hydromorphone Induction: Ketamine + Diazepam Maintenance: Sevoflurane Intra-op / Post-op: LS Epidural (Morphine + Bupivacaine) + Post-op carprofen