Lecture 13 Special Considerations in Anesthesia Part 1

Question 1

What are 2 anesthetic concerns for liver disease

Answer 1

1. —Glucose homeostasis
   
   • —Hypoglycemia
2. —↓ Drug Metabolism
   
   • —Prolonged recovery
3. —↓ Protein Synthesis

Question 2

What does decrease protein synthesis cause in patients with liver failure regarding anesthesia

Answer 2

1. —Drug binding
   
   • —drugs protein bound
   • —↑ unbound drug, ↑ effect
2. —Oncotic pressure
   
   • —albumin 80% oncotic pressure
   • —Hypotension
3. —Coagulation Factors
   
   • —↑ hemorrhage, blood loss

Question 3

What are the liver assessment tests

Answer 3

1. —ALT
   
   • —alanine transaminase
   • —‘leakage enzyme’
2. —ALP
   
   • —alkaline phosphatase
   • —cholestatsis
3. —Substances the liver makes
   
   • —BUN*
   • —Glucose*
   • —Albumin*
   • —Clotting Factors*
   • —Cholesterol
   • —Total Bilirubin, ↑indirect
   • —Bile Acids ​

Question 4

1. What is the value of glucose you don’t want for anesthesia
2. What can you do to fix it

Answer 4

1. < 60-70mg/dl
   
   • —Intra-op monitoring every hour
2. —Intra-op supplementation of —2.5-5% dextrose in IV fluids

Question 5

1. clinical signs by hypoglycemia
2. How can anesthesia affect these signs?

Answer 5

1. —Seizures, CNS depression
2. —Masked by anesthesia

Question 6

What are drugs that are not metabolized by liver used in anesthesia

Answer 6

1. —Inhalants
   
   • —Isoflurane .17%
   • —Sevoflurane 3-5%
   • —Desflurane 0%
   • —Nitrous Oxide 0%
2. —Propofol
   
   • —Extra-hepatic sites of metabolism
   • —Very short acting, 5-10 min
3. —Drugs that are reversible

Question 7

Order the inhalants of least to most that are metabolized by liver

Answer 7

1. —Desflurane 0%
2. —Nitrous Oxide 0%
3. —Isoflurane .17%
4. —Sevoflurane 3-5%

Question 8

What are the —Drugs that are reversible and what reverses them

Answer 8

1. —Opioids full mu agonists
   
   • —Morphine, Hydromorphone, Fentanyl
   • —Full reversal Naloxone
   • —Partial reversal Butorphanol
2. —Benzodiazepines
   
   • —Midazolam, Diazepam
   • —Flumazanil $$$
3. —Alpha-2 agonists
   
   • —Dexmedetomidine
   • Atipamazole

Question 9

—Drug Binding

—↓ dose, reversible drugs, drugs not metabolized by liver

Question 10

1. Because there is —↓ Oncotic pressure because of ↓Albumin what fluids will you use?
2. How will you treat hypotension

Answer 10

1. —Collioids
   
   • —Plasma, if practical
   • —Hetastarch
2. —Hypotension
   
   • —‘balanced anesthesia’ techniques, Isoflurane sparing
     
     • —Fentanyl CRI, nitrous oxide
   • —Vasopressors & positive inotropes

Question 11

What can you use to treat ↓ Clotting Factors during anesthesia

Answer 11

1. —Fresh Frozen Plasma
   
   • —Provides albumin & clotting factors
   • —May not be practical in large dogs for oncotic support
     
     • —Need 45ml/kg to raise albumin by 1g/dl
2. —Monitor Blood Loss
   
   • —Calculate total blood volume, allowable loss
   • —Quantitate blood loss intra-operatively
   • —Replace blood as indicated

Question 12

What % of tissues are found in the brain

Answer 12

• —Brain tissue 80%
• —CSF 10%
• —Blood 10%

Question 13

What does the —Monroe-Kellie Doctrine say

Answer 13

• —↑ in volume of one of the cranial constituents must be compensated by a ↓ in volume of another
• —↓CSF production, ↑CSF absorption

Question 14

What are causes of patients with neurolgic disease

Answer 14

1. —Brain tumor
2. —Trauma with brain edema
3. —Infectious disease/abcess
4. —Seizures => brain edema
5. —Hydrocephalus

Question 15

1. What is the MAP that you want during anesthesia
2. What do you want to do with cerebral blood flow (CBF)

Answer 15

1. —60 – 150 mmHg
2. —Do NOT ↑CBF

Question 16

1. What drugs can you use that do not increase cerebral blood flow (CBF)
2. Which drug to avoid?
3. What parameter is the biggest determinant of CBF

Answer 16

1. —Propofol, low dose inhalants
2. —Avoid Ketamine
3. —Keep PaCO2 in normal range =>
   
   • — 35 – 40mmHg
   • Use— IPPV ​

Question 17

Cushing reflex

Answer 17

pressure increases in brain and then body will have to increase systemic blood pressure

Question 18

1. How do you monitor —Sudden, severe ↓ in HR
2. How to treat
3. What is a critical time for brain herniation

Answer 18

1. Check MAP
2. —Hypertonic Saline, mannitol
3. —*Induction is critical time

Question 19

What are general strategies for Patients with Cardiac Disease

Answer 19

1. —Maintain Cardiac Output
2. —Maintain good oxygenation/ventilation
3. —Avoid fluid overload
4. —Avoid hypo- or hypertension
5. —Avoid bradycardia or tachycardia
6. —Avoid ↑ myocardial work & O2 consumption
7. —Avoid drugs that cause arrhythmias & myocardial depression
8. —Use drug with mild CV effects
9. —‘Balanced Anesthesia’ & multi-modal approach
10. —Low dose Acepromazine to ↓stress, promote forward flow
11. —Judicious use of anti-cholinergics
12. —Pre-oxygenate
13. —↓ IV fluid rate

Question 20

What are drugs with mild cardiovascular effects

Answer 20

1. —Opioids –
   
   • pure u-agonists: Hydromorphone, Oxymorphone, Fentanyl, Morphine
2. —Benzodiazepines
   
   • Midazolam, Diazapam
3. —Etomidate, alphaxalone
4. —Nitrous Oxide

Question 21

What is the benefit of using Acepromazine for cardiac disease animals

Answer 21

• —to ↓stress
• promote forward flow so that BP and HR doesnt increase

Question 22

Why do you want to have a —Judicious use of anti-cholinergics for cardiac disease

Answer 22

If you decrease vagal tone you will increase HR

Question 23

1. What is the —Most common degenerative heart disease in dogs
2. Do you just need to know the diagnosis for this disease?

Answer 23

1. Mitral Valve Regurgitation
   
   • enlargement of right atrium
   • back up into lungs
2. —Progressive disease/need to establish extent of cardiac dysfunction

Question 24

1. What is the common cardiomyopathy in cats
2. What other disease is it associated with

Answer 24

1. Hypertrophic cardiomyopathy
2. —Associated with hyperthyroidism

Question 25

1. What will yo usee to HR with a cat with hypertrophic cardiomyopathy
2. BP?
3. Organ status

Answer 25

1. —Tachycardia, murmur, ‘gallop’ rhythm
2. —Hypertension,
3. renal failure

Question 26

How do you treat cats with hypertrophic cardiomyopathy or hyperthyroidism for anesthesia

Answer 26

1. —Stabilize pre-op with anti-thyroid, cardiac meds
2. —Avoid stress, tachycardia
3. —Opioid
   
   • —+/- Alphaxalone
   • —+/- benzodiazepine
   • —+/- low dose Acepromazine
   • —+/- low dose Dexmedetomidine

Question 27

What are the 2 general patients with respiratory disease

Answer 27

1. —Lower airway disease:
   
   • pneumonia, asthma, contusions
2. —Extra-pulmonary disease:
   
   • pneumothorax, pleural effusion, Diaphragmatic hernia
     
     • —!! Evacuate air, fluid !!

Question 28

How do you anesthetize Patients with Respiratory Disease

Answer 28

1. —Preoxygenate
2. —Rapid IV induction/intubation
3. —100% O2, +/- IPPV
4. +/- Positive end expiratory pressure (PEEP)
   
   • will hold pressure in alveoli

Question 29

What are the different problems with Brachycephalic Syndrome

Answer 29

1. —Stenotic nares
2. elongated soft palate
3. excessive pharyngeal tissue
4. everted laryngeal saccules
5. hypoplastic trachea => Upper Airway Obstruction

Question 30

How do you premedicate brachycephalic syndrome animals

Answer 30

1. —+/- LOW dose Acepromazine
   
   • —relieve stress from uppper airway obstruction/hypoxemia
2. —+/- Anticholinergics
   
   • —high vagal tone from uppper airway obstruction
3. —Continuous observation
4. —Variety of ET tube sizes 6.0-10mm

Question 31

How do you induce brachycephalic syndrome animals

Answer 31

1. —Pre-oxygenate
2. —Rapid IV induction/intubation
   
   • —Propofol drug of choice
     
     • quick recovery without residual effects

Question 32

How do you recover brachycephalic syndrome animals

Answer 32

1. —Continue O2, monitor SpO2
2. —Leave in IV catheter
3. —Sternal position, head elevated
4. —Quiet/dim light surroundings
5. —Leave in ET tube as long as possible
6. —Be prepared to re-intubate
   
   • —Laryngoscope, ET tube, induction agent, O2 source/IPPV (anesthetic machine)
7. —Monitor SpO2 after extubation
   
   • —Sternal, prop open mouth, extend tongue