Lesson 1 - Introduction to the course, anesthesia planning. Premedication.

What is the first phase of anesthesia?

pre-anesthetic assessment

What is the second phase of anesthesia?

premedication

What is the third phase of anesthesia?

IV catheter placement

What is the fourth phase of anesthesia?

induction/intubation

What is the fifth phase of anesthesia?

maintenance

What is the sixth phase of anesthesia?

recovery

A veterinary practice is reviewing their anesthetic protocols to improve patient safety. The practice manager asks you to identify when most anesthetic-related deaths occur so they can allocate additional monitoring resources and staff training to that critical period. What phase of the anesthetic process should be prioritized for enhanced safety measures?

recovery period

Why should you always be giving the patient O2 during IV catheter placement?

drugs can cause respiratory depression

What is an important part of the maintenance phase?

anesthesia record that records parameters every five minutes

What happens during the recovery phase?

turn off and remove monitoring devices except for O2, turn off inhalant anesthetics, give O2 for five minutes, disconnect O2, wait until the patient swallows before de-puffing and removing tube

A 4-year-old Labrador Retriever is scheduled for an orthopedic surgery. After completing the physical examination and obtaining owner consent, the veterinarian administers acepromazine and morphine intramuscularly. The dog is placed in a quiet kennel with a towel over the cage. What phase of anesthesia is being performed?

preanesthetic medication

What are the important components of a preanesthetic evaluation?

1. history

2. physical exam

3. age

4. species, breed, size

5. temperament

What history is important to know before administering anesthesia?

1. medical conditions

2. adverse drug reactions

3. current medications

4. prior anesthetic experiences

When should the physical exam be completed?

12-24 hours before anesthesia and repeated if acute changes occur

What age patients often have altered drug responses and increased anesthetic risk?

neonatal and pediatric

What age patients often have health issues that make anesthesia more challenging?

geriatric

What are some size/breed/species factors that should be considered?

1. anatomical factors (brachycephalics)

2. breed-specific predispositions (cardiac issues)

3. hypothermia in small patients

4. overdosing in giant breeds

What preanesthetic diagnostics should be run in young healthy dogs?

1. hematocrit

2. total protein

3. creatinine

4. glucose

What preanesthetic diagnostics should be run in young healthy cats?

1. hematocrit

2. total protein

3. creatinine

4. BUN

5. glucose

What preanesthetic diagnostics should be run in young healthy rabbits?

1. hematocrit

2. total protein

3. glucose

What preanesthetic diagnostics should be run in critically ill patients?

CBC, total protein, albumin, biochem, blood gas analysis, urinalysis, ECG, x-rays, abdominal ultrasound, coagulation tests

What are some anesthesia planning considerations?

1. ASA status categorization

2. Risk factor mitigation

3. Procedure considerations

4. Equipment preparation

5. Anesthetic protocol

6. Fasting time

7. Owner consent

What is an ASA I?

normal patient with no disease

What is an ASA II?

patient with mild systemic disease that does not limit normal function

What is an ASA III?

patients with severe systemic disease

What is an ASA IV?

patient with severe systemic disease that is aconstant threat to life

What is an ASA V?

moribund patients not expected to survive 24h without intervention

What is an ASA E?

emergency (delay in treatment of the patient would lead to significant increase in the threat to life or body part)

What is an example of an ASA I?

heathy patient scheduled for elective procedure like castration

What are some examples of an ASA II?

controlled diabetes mellitus, mild cardiac valve insufficiency, skin tumor

What are some examples of an ASA III?

uncontrolled diabetes mellitus, symptomatic heart disease

What are some examples of an ASA IV?

sepsis, organ failure, heart failure, toxemia

What are some examples of an ASA V?

multiple organ failure, severe shock, severe trauma

What are some examples of an ASA E?

GDV, colics, open fracture

What are some risk factors?

1. age

2. species

3. breed

4. health condition

5. type of procedure

What are some age related risk factor for geriatric patients?

impaired cognitive or organ function that alters drug responses

What are some age related risk factor for neonatal patients?

immature liver function limiting the metabolism of anesthetic drugs

What species are prone to laryngospasm?

cats and pigs

What species is very sensitive to some sedatives?

ruminants

What breed is at a higher risk for upper airway obstruction?

brachycephalics

What breed is very sensitive to acepromazine?

boxers

What breed is commonly affected by MDR1 mutation?

collies

What dogs breeds are prone to heart disease?

large breeds

What are some actions that can be taken to mitigate anesthetic risk?

1. Preanesthetic physical exam

2. Premedication to reduce stress

3. Dedicated anesthetist

4. IV catheter placement

5. Oxygen supplementation

6. Comprehensive monitoring (Cardiovascular, Respiratory, Temp)

7. Continued monitoring in recovery

What are the procedure considerations?

1. Type of procedure (soft tissue, orthopedic)

2. Length of the procedure

3. Possible complications

4. Patient's position

5. X-rays?

What equipment preparations are needed?

1. IV catheter

2. Intubation

3. Fluid pumps/syringe drivers

4. Breathing system

5. Anesthesia machine

6. Monitoring

7. Ventilator

8. Crash cart

How long should food be withheld from healthy adult patients before anesthesia?

4-6 hours

How long should food be withheld from patients <8 weeks or <2kg before anesthesia?

no longer than 1-2 hours

How long should food be withheld from diabetic patients before anesthesia?

2-4 hours

How long should water be withheld from patients before anesthesia?

0 hours

How long should food and water be withheld from patients with a history of or a high risk for regurgitation?

6-12 hours

What should you explain to owners before having them sign a consent form?

1. procedure

2. pet-specific risks

3. reassure them that a dedicated anesthetist and an individualized plan are in place to maximize safety

4. never declare that there are no risks (even an ASA I has a risk)

A 7-year-old Labrador retriever is presented for removal of a small benign lipoma on the shoulder. The dog has well-controlled diabetes mellitus managed with insulin therapy and regular monitoring, and the owner reports no recent complications. Physical examination reveals normal cardiovascular and respiratory parameters. What is the most appropriate ASA status for this patient?

ASA II

What is the anesthetic mortality rate for dogs?

0.69%

What is the anesthetic mortality rate for cats?

0.63%

What is the anesthetic mortality rate for horses?

1.2%

What is the anesthetic mortality rate for rabbits?

2.05%

What can increase anesthetic mortality risk in dogs?

↑ ASA status, age, obesity, surgery type, schedule and duration

What can increase anesthetic mortality risk in cats?

↑ ASA status, cachexia, mechanical ventilation, type of surgery

What can increase anesthetic mortality risk in horses?

↑ ASA status, surgery schedule and duration, colic, ketamine CRI, age, pregnant

What can increase anesthetic mortality risk in rabbits?

↑ ASA status, ↓weight (<1kg), nonroutine procedures, fentanyl-based protocols, Netherland Dwarf rabbits

What can decrease anesthetic mortality risk in dogs?

sedatives, opioids, NSAIDs, locoregional anesthesia, sevoflurane

What can decrease anesthetic mortality risk in cats?

Alpha2 agonists, opioids, locoregional anesthesia

What can decrease anesthetic mortality risk in horses?

monitoring invasive arterial pressure, end-tidal CO2, blood gases and body temperature. Combination of agonistantagonist opioids and NSAIDs, Alpha2 agonists during recovery

What can decrease anesthetic mortality risk in rabbits?

supraglottic device (V-gel), medetomidine-based protocols

Why are premeds used?

1. Calming effect

2. Facilitate handling

3. Analgesia

4. Reduce sympathetic responses

5. Reduce anesthetic requirements

6. Smooth induction and recovery

What are the categories of medications that are used for preanesthetics?

1. phenothiazines

2. benzodiazepines

3. alpha 2 adrenergic receptor agonists

4. butyrophenones

5. opioids

6. trazadone

What are the main effects of acepromazine?

1. sedation

2. hypotension

3. hypothermia

4. antiarrhythmic

5. antiemetic

6. antihistaminic

What are the main receptors that acepromazine antagonizes?

1. dopamine 1

2. dopamine 2

3. alpha 1

What pre-med drug has no reversal and provides no analgesia?

acepromazine

What is the duration of action of acepromazine?

4-6 hours

What using acepromazine for a preanesthetic, what other type of drug would you want to combine with it?

opioid

What is the onset of action like for acepromazine?

slow

What drug causes splenic sequestration of RBC and platelets?

acepromazine

What could occur after a patient becomes hypotensive from acepromazine?

decrease in PCV up to 20% from splenic sequestration

Why does acepromazine cause tachycardia?

adrenaline can't bind to alpha-1 so it binds to beta-1 receptors in the heart

Why is there an increased risk of gastroesophageal reflux with acepromazine?

reduces lower gastroesophageal sphincter tone

How does a boxer present when given acepromazine?

heavy sedation and hypotension with bradycardia

What do we use acepromazine for during recovery?

help manage opioid-induced dysphoria

What are the contraindications for acepromazine?

1. breeding stallions

2. hypovolemia

3. dehydration

4. hypotension

5. coagulopathies

6. anemia

What premed is not reliable in cats?

acepromazine

What ASA levels can we use acepromazine for?

ASA 1-3

What premed is good for long sedations and transportation?

acepromazine

What are the receptors responsible for the sedative effect of acepromazine?

dopamine 1 & 2 receptors

What are the main effects of alpha-2 agonists?

1. sedation

2. muscle relaxation

3. analgesia

4. hypertension

5. bradycardia

6. emetic

What is the duration of action of alpha-2 agonists?

1 - 1.5 hours

What drugs produce a dose-dependent biphasic hemodynamic effect?

alpha-2 agonists

What is part of phase 1 of the biphasic hemodynamic effect?

peripheral vasoconstriction and hypertension followed by reflex bradycardia

How long does phase 1 of the biphasic hemodynamic effect last?

20 minutes

What is part of phase 2 of the biphasic hemodynamic effect?

blood pressure returns to normal but bradycardia remains due to presynaptic CNS effects

What secretion is decreased with alpha-2 agonists?

1. insulin

2. ADH

3. renin

When would we want to use an alpha-2 agonist along with a benzidiazepine?

non-painful procedures like diagnostic imaging

What are the contraindications for alpha-2 agonists?

1. pediatric patients

2. patients with cardiovascular disease

3. critically ill patients

4. blocked cats

5. diabetic patients

What reversal drug do we use when reversing sedative, analgesic, and cardiovascular effects of alpha-2 agonist?

atipamezole

What reversal drug do we use when reversing only cardiovascular effects of alpha-2 agonists?

vatinoxan

What are benzodiazepines used for?

1. anxiolytic sedative

2. muscle relaxant

What type of drugs has a reversal agent but provides no analgesia?

benzodiazepines

What is the reversal agent for benzodiazepines?

flumazenil

What receptor do benzodiazepines act on?

positive modulators of GABA

Why do we not use benzodiazepines in healthy dogs and cats?

may cause excitation instead of sedation