VTNE Veterinary Anesthesia 2 — Questions and Answers
Question 1: Which breathing system is MOST appropriate for patients weighing less than 7 kg due to its low resistance and minimal rebreathing?
- Circle rebreathing system
- Mapleson F (Norman Elbow) system (Correct answer)
- To-and-fro system
- Large animal circle system
Correct answer: Mapleson F (Norman Elbow) system
The Mapleson F system (Norman Elbow/Bain modification) is preferred for small patients because it offers low resistance and reduces rebreathing without requiring a CO2 absorber.
Question 2: A dog under inhalant anesthesia shows a sudden decrease in end-tidal CO2 from 45 mmHg to 15 mmHg. What is the MOST likely cause?
- Hypoventilation
- Pulmonary thromboembolism or cardiac arrest (Correct answer)
- Hyperthermia
- Excessive anesthetic depth
Correct answer: Pulmonary thromboembolism or cardiac arrest
A sudden dramatic drop in EtCO2 is a classic sign of pulmonary thromboembolism or cardiac arrest, where CO2 delivery to the lungs ceases.
Question 3: What is the primary mechanism of action of acepromazine as a preanesthetic?
- Alpha-2 adrenergic agonism
- Dopamine receptor antagonism (Correct answer)
- NMDA receptor antagonism
- Opioid receptor agonism
Correct answer: Dopamine receptor antagonism
Acepromazine is a phenothiazine tranquilizer that works primarily by blocking dopamine receptors in the CNS, producing sedation and reducing anxiety.
Question 4: During anesthesia, a cat's respiratory rate drops to 4 breaths per minute. Which intervention is MOST appropriate?
- Increase the vaporizer setting
- Administer atropine IV
- Assist or control ventilation manually (Correct answer)
- Administer doxapram IV
Correct answer: Assist or control ventilation manually
Severe hypoventilation requires immediate ventilatory support via manual or mechanical ventilation to prevent hypercapnia and hypoxemia.
Question 5: Which of the following is the CORRECT placement site for a pulse oximeter probe in an anesthetized dog?
- Dorsal surface of the carpus
- Lingual (tongue) mucosa (Correct answer)
- Corneal surface
- Dorsal pedal artery
Correct answer: Lingual (tongue) mucosa
The tongue is one of the most reliable sites for pulse oximetry in dogs because of good tissue perfusion and minimal pigmentation interference.
Question 6: What does a 'pop-off' (pressure relief) valve set to 2 cm H2O on an anesthesia machine primarily prevent?
- Rebreathing of CO2
- Barotrauma from excessive airway pressure (Correct answer)
- Oxygen flush activation
- Vaporizer overfill
Correct answer: Barotrauma from excessive airway pressure
The pop-off valve vents excess gas to prevent dangerous airway pressure buildup that could cause pulmonary barotrauma.
Question 7: Which local anesthetic has the LONGEST duration of action and is commonly used for epidural analgesia in veterinary patients?
- Lidocaine
- Procaine
- Bupivacaine (Correct answer)
- Mepivacaine
Correct answer: Bupivacaine
Bupivacaine has the longest duration of action (4–8 hours) among commonly used veterinary local anesthetics and is preferred for epidural analgesia.
VTNE Veterinary Anesthesia 2
Which breathing system is MOST appropriate for patients weighing less than 7 kg due to its low resistance and minimal rebreathing?