DVM Anesthesia and Surgical Principles 2 — Questions and Answers
Question 1: Which inhalant anesthetic has the highest blood:gas partition coefficient, resulting in the slowest induction and recovery?
- Isoflurane
- Sevoflurane
- Halothane (Correct answer)
- Desflurane
Correct answer: Halothane
Halothane has the highest blood:gas partition coefficient (~2.4) among common inhalants, meaning more drug must dissolve in blood before equilibrium is reached, slowing induction and recovery.
Question 2: A dog is in Trendelenburg position during abdominal surgery. Which physiologic consequence is most likely?
- Decreased venous return
- Increased intracranial pressure (Correct answer)
- Decreased cardiac preload
- Hypercapnia from reduced minute ventilation
Correct answer: Increased intracranial pressure
Trendelenburg (head-down) position shifts abdominal contents cranially and increases intracranial pressure by impeding venous drainage from the head.
Question 3: Which opioid is most appropriate for epidural analgesia in dogs due to its hydrophilicity and prolonged duration of action?
- Fentanyl
- Morphine (Correct answer)
- Buprenorphine
- Butorphanol
Correct answer: Morphine
Morphine's high hydrophilicity limits its spread within the epidural space, producing prolonged segmental analgesia lasting 12–24 hours.
Question 4: During anesthesia, a cat develops a heart rate of 240 bpm with narrow QRS complexes and no visible P waves. The most likely diagnosis is:
- Ventricular tachycardia
- Atrial fibrillation
- Supraventricular tachycardia (Correct answer)
- Third-degree AV block
Correct answer: Supraventricular tachycardia
Supraventricular tachycardia presents with narrow QRS complexes (indicating normal ventricular conduction) and absent or hidden P waves at rapid rates.
Question 5: Which local anesthetic has the longest duration of action and is most cardiotoxic in overdose?
- Lidocaine
- Mepivacaine
- Bupivacaine (Correct answer)
- Procaine
Correct answer: Bupivacaine
Bupivacaine provides the longest duration of local anesthesia but binds cardiac sodium channels with high affinity, making cardiac resuscitation after toxicity extremely difficult.
Question 6: Which parameter best reflects the minimum alveolar concentration (MAC) needed to prevent movement in 50% of patients exposed to a painful stimulus?
- ED50 of the inhalant in blood
- Alveolar partial pressure at steady state (Correct answer)
- Brain partial pressure at induction
- Inspired concentration during induction
Correct answer: Alveolar partial pressure at steady state
MAC is defined as the alveolar (end-tidal) partial pressure of an inhalant at steady state that prevents purposeful movement in 50% of subjects.
Question 7: A horse undergoing general anesthesia in lateral recumbency develops hypoxemia refractory to increasing FiO2. The most likely cause is:
- Hypoventilation alone
- Ventilation-perfusion mismatch due to dependent lung atelectasis (Correct answer)
- Anesthetic circuit disconnect
- Endobronchial intubation
Correct answer: Ventilation-perfusion mismatch due to dependent lung atelectasis
In lateral recumbency, the dependent lung receives more perfusion but less ventilation due to atelectasis and diaphragm compression, causing V/Q mismatch and refractory hypoxemia.
DVM Anesthesia and Surgical Principles 2
Which inhalant anesthetic has the highest blood:gas partition coefficient, resulting in the slowest induction and recovery?