Anesthesia

Question 1

During anesthesia, which physiological change most directly increases the risk of gastroesophageal reflux?

Answer 1

Decreased lower esophageal sphincter tone, which allows gastric contents to move into the esophagus more easily

Question 2

How many physical status classes are included in the American Society of Anesthesiologists classification system as applied to veterinary patients, and which class designates the highest risk patient?

Answer 2

Five classes; V is extreme risk, a moribund patient that is not expected to survive without the procedure

(class I is a normal, healthy patient)

An example of class V is a dog with gastric dilatation-volvulus.

Question 3

What does the letter “E” indicate when added to an American Society of Anesthesiologists physical status classification?

Answer 3

That the procedure is an emergency

Question 4

Why are multiple pharmacologic classes of drugs used in a balanced anesthesia technique?

Answer 4

Because no single agent provides all required anesthetic effects

(e.g., muscle relaxation, amnesia, unconsciousness, and analgesia)

Question 5

Which receptor interaction best explains the sedative and analgesic effects of opioids commonly used in veterinary anesthesia?

Answer 5

μ-opioid receptor agonism leads to decreased neurotransmitter release in pain pathways

Question 6

What is the primary role of antagonist drugs such as those used in opioid or alpha₂-adrenergic classes?

Answer 6

To block or reverse the effects of corresponding agonists

e.g., naloxone is an opioid receptor antagonist used to reverse opioids like morphine; yohimbine is an alpha₂-adrenergic antagonist used to reverse alpha₂-adrenergic agonists like xylazine.

Question 7

A cat received an overdose of hydromorphone and experienced respiratory arrest. What drug should you give to reverse the opioid?

• A. Butorphanol
• B. Flumazenil
• C. Naloxone
• D. Ketamine

Answer 7

C. Naloxone

(it is an opioid antagonist)

In respiratory arrest due to opioid overdose, give an antagonist to completely reverse the effects of the opioid. Butorphanol is a mixed agonist-antagonist and would be inappropriate in this situation.

Question 8

Why are anticholinergic drugs used in anesthetic management for some species, even though they are not true anesthetic agents?

Answer 8

To counteract parasympathetic effects

(e.g., bradycardia and excess salivation)

They are commonly used in dogs and cats and rarely used in horses and ruminants.

Question 9

Which anesthetic drug classes are especially likely to cause bradycardia, potentially necessitating anticholinergic use?

Answer 9

Opioids and alpha₂-adrenergic agonists

Question 10

What are the key differences between atropine and glycopyrrolate?

Answer 10

Glycopyrrolate:
* Has a slower onset and longer duration
* Is less likely to cause tachycardia or ileus
* Suppresses salivation more effectively
* Does not cross the blood-brain or placental barriers

Question 11

Define:

The ceiling effect, when referring to an anesthetic or sedative agent

Answer 11

A ceiling effect occurs when increasing the dose of a drug no longer increases the desired effect, but may increase the risk of adverse effects

(an example of a drug with a ceiling effect is acepromazine)

Question 12

What is the main mechanism responsible for the most significant adverse effect of acepromazine?

Answer 12

Acepromazine blocks alpha₁-adrenergic receptors, leading to peripheral vasodilation and hypotension

Question 13

What are the effects of benzodiazepines?

Answer 13

• Sedation
• Anxiety reduction
• Skeletal muscle relaxation
• Anticonvulsant

Question 14

Which cardiovascular effect is commonly associated with administration of alpha₂-adrenergic agonists?

Answer 14

Initial hypertension, followed by prolonged hypotension, along with bradycardia and decreased cardiac output

Question 15

Which species is more sensitive to xylazine: bovines or equines?

Answer 15

Bovines

(they require only about 10% of the dose used in horses)

Question 16

Why is routine use of anticholinergics with alpha₂-adrenergic agonists generally discouraged?

Answer 16

Can further decrease cardiac output, increase myocardial workload, and predispose patients to arrhythmias and hypertension

Question 17

What is the preferred administration route of alpha₂-antagonists in dogs and cats in non-emergent settings?

Answer 17

Intramuscular

(they can be given slowly IV in a crisis such as cardiac arrest)

Note: typically given IV in horses and ruminants

Question 18

Which receptor is primarily responsible for the analgesic and respiratory depressive effects of opioid agonists?

Answer 18

Mu receptor

Agonism produces analgesia, respiratory depression, miosis, hypothermia, and euphoria

Question 19

Name two drugs that could reverse or partially reverse opioids.

Answer 19

• Naloxone (complete reversal)
• Butorphanol (partial reversal - this is a mixed agonist-antagonist)

Question 20

Which adverse effect is most concerning immediately after rapid IV administration of propofol?

Answer 20

Apnea and respiratory depression

Question 21

Why should propofol be administered cautiously in hypotensive patients?

Answer 21

It worsens hypotension by causing vasodilation and decreased cardiac contractility

Question 22

Which dissociative anesthetic agents are most commonly used in veterinary patients?

Answer 22

• Ketamine
• Tiletamine

Question 23

Which cardiovascular effect is characteristic of dissociative anesthetics?

(e.g., ketamine)

Answer 23

Increased heart rate and blood pressure due to sympathetic nervous system stimulation

Question 24

What is the primary clinical use of guaifenesin in veterinary anesthesia?

Answer 24

Injectable muscle relaxant and sedative

It is administered in combination with other anesthetic agents, particularly in large animal patients, to improve induction and recovery or for short procedures.

Question 25

What does **minimum alveolar concentration** (MAC) represent?

Answer 25

The concentration preventing movement in 50% of patients | (a measure of anesthetic potency)

Question 26

# Define: Blood-gas partition coefficient

Answer 26

Measurement of tendency of an inhalant anesthetic agent to dissolve in blood ## Footnote Agents with a low blood-gas partition coefficient dissolve less in blood, resulting in faster induction and recovery.

Question 27

Why might **sevoflurane** be preferred for **mask induction** over isoflurane?

Answer 27

Sevoflurane does not irritate mucous membranes | (and this reduces patient breath-holding and struggling)

Question 28

Which **endotracheal tube feature** allows airflow if the tip becomes **occluded**?

Answer 28

The Murphy eye - it is a side opening towards the distal end of the tube ## Footnote It permits airflow if the distal tip occludes.

Question 29

What measurement is used to describe **endotracheal tube size**?

Answer 29

Internal diameter | (expressed in millimeters)

Question 30

Which system of the **anesthesia machine** is responsible for delivering oxygen at a **controlled flow rate**? * A. Scavenging system * B. Anesthetic vaporizer * C. Carrier gas supply * D. Breathing circuit

Answer 30

C. Carrier gas supply

Question 31

What does the **flowmeter** on an anesthesia machine **control**?

Answer 31

Regulates the flow of oxygen and other carrier gases

Question 32

What does an **anesthetic vaporizer** do?

Answer 32

Converts liquid anesthetic into a precise concentration of vapor and mixes it with carrier gases

Question 33

What is the purpose of a **scavenger system** of an anesthesia machine?

Answer 33

Removes waste anesthetic gases from the anesthesia machine | (to reduce environmental contamination and personnel exposure)

Question 34

You are checking an anesthetic nonrebreathing system for leaks, and the reservoir bag, filled to 30 cm H₂O, stays inflated for at least 10 seconds after oxygen flow is stopped. **What does this finding tell you about the system?** * A. Need to change the sodalime * B. There is a slow leak but the system is safe to use * C. The pressure manometer is broken * D. The system is leak-free

Answer 34

D. The system is leak-free

Question 35

# True or False: The **pop-off valve** allows excess gas to escape from the breathing circuit, preventing overpressurization and potential lung injury.

Answer 35

True

Question 36

Which type of **anesthetic breathing circuit** is recommended for patients **weighing < 7 kg**?

Answer 36

Nonrebreathing systems are recommended for small patients (< 7 kg) | (because they minimize resistance to airflow)

Question 37

What is a **major advantage** of an anesthetic **rebreathing** system compared with a nonrebreathing system?

Answer 37

Conserve heat and moisture by allowing recirculation of exhaled gases

Question 38

Which factor can cause a **reservoir bag** to **overfill**?

Answer 38

Closed pop-off valve ## Footnote If this occurs, the patient can develop pneumothorax, which may be fatal.

Question 39

What happens to the patient's **blood pH** if the **CO₂ absorbent** granules in the anesthesia machine are **saturated**?

Answer 39

pH decreases as CO₂ buildup in the blood stream leads to hypercapnia and respiratory acidosis

Question 40

Why should **pediatric breathing tubes** be used in small patients undergoing anesthesia?

Answer 40

Reduce mechanical dead space and resistance

Question 41

What is the **effect of dead space** on patient respiration? * A. No effect * B. Reduces fresh oxygen delivery to alveoli * C. Increases risk of pneumothorax * D. Causes apnea

Answer 41

B. Reduces fresh oxygen delivery to alveoli

Question 42

A universal F-circuit may be used when anesthetizing a small animal patient. **What is the purpose of this circuit?**

Answer 42

Inhalation tube is positioned within the exhalation tube, so that warm expired gases warm incoming gases, conserving body heat

Question 43

Which problem may occur if an **endotracheal tube** is **too long** and advanced into only one mainstem bronchus?

Answer 43

Inadequate ventilation and hypoxemia

Question 44

What is the recommended **end position** of an **endotracheal tube** in most patients?

Answer 44

Tip of the nose to the thoracic inlet

Question 45

What diameter of **endotracheal tube** is typically prepared for an **adult horse**?

Answer 45

22-30 mm

Question 46

# True or False: **Endotracheal intubation** is performed blindly in **horses**

Answer 46

True | (because cannot visualiz the larynx from the mouth in horses)

Question 47

What **drug**, when topically applied, **reduces laryngospasm**?

Answer 47

Lidocaine

Question 48

# True or False: When **intubating** a **ruminant** be sure to keep the head below the rumen to reduce the risk of passive regurgitation.

Answer 48

False ## Footnote Keep the head slightly extended and elevated to minimize risk of regurgitation and aspiration during intubation.

Question 49

What does **palpation** of two firm tubular structures in the neck suggest during endotracheal **intubation**?

Answer 49

Esophageal intubation | (i.e., palpating the trachea AND the tube in the esophagus) ## Footnote You should only be able to palpate one firm tubular structure (the trachea) if the tube is properly in the trachea.

Question 50

Why is checking **unidirectional valve motion **of an anesthetic circuit not always reliable for **confirming endotracheal tube placement**?

Answer 50

Valve motion can coincide with bag movement even if the tube is misplaced into the esophagus

Question 51

If the ETCO₂ monitor shows a **flatline waveform after intubation**, what is the most likely cause?

Answer 51

Tube malpositioned in the esophagus or disconnection in the circuit

Question 52

What is the most likely **complication** if an endotracheal tube cuff is **underinflated**?

Answer 52

Aspiration of stomach contents or foreign material into the airway/lung ## Footnote This leads to aspiration pneumonia, which can be fatal.

Question 53

Which **complication** is associated with an **overinflated** endotracheal tube cuff?

Answer 53

Tracheal necrosis and possible tracheal rupture

Question 54

Which **stage** of general anesthesia is also called the **“excitement stage”**, characterized by involuntary movements, irregular breathing, and elevated heart rate?

Answer 54

Stage II, period of involuntary movement

Question 55

What is **stage II anesthesia** characterized by?

Answer 55

* Progressive muscle relaxation * Decreasing heart and respiratory rates * Loss of reflexes

Question 56

Name **two ocular signs** observed during **stage III anesthesia** as the patient progresses from light to deep surgical anesthesia.

Answer 56

* Pupils gradually dilate * Tear production decreases * Pupillary light reflex is lost

Question 57

Which **reflex** is generally absent in small animals during **surgical anesthesia** but should still be present in horses and ruminants until a moderately deep plane of anesthesia?

Answer 57

Palpebral reflex

Question 58

# True or False: A **ventromedial eye position** in anesthetized patients usually indicates they are in a plane of **surgical anesthesia**.

Answer 58

True

Question 59

Name **three factors** that affect **pulse oximetry** probe function.

Answer 59

* Tissue pigmentation * Motion * Excessive pressure * Ambient lighting * Anemia * Icterus * Vasoconstriction * Edema

Question 60

What are the positive effects of **preoxygenating a patient** prior to anesthetic induction?

Answer 60

Increases body's oxygen storage and tolerance of apnea