NAVLE Veterinary Anesthesia and Pain Management 2 — Questions and Answers
Question 1: A dog under isoflurane anesthesia has an end-tidal CO2 (ETCO2) reading of 62 mmHg. What does this finding indicate?
- Adequate ventilation
- Hyperventilation with CO2 washout
- Hypoventilation with CO2 retention (Correct answer)
- Adequate tissue oxygenation
Correct answer: Hypoventilation with CO2 retention
Normal ETCO2 in anesthetized patients is 35–45 mmHg; a value of 62 mmHg indicates hypoventilation, meaning the patient is not eliminating CO2 adequately and intervention (e.g., manual or mechanical ventilation) is needed.
Question 2: Minimum alveolar concentration (MAC) is the inhalant anesthetic concentration that prevents gross movement in response to surgical stimulation in what percentage of patients?
- 25%
- 50% (Correct answer)
- 75%
- 100%
Correct answer: 50%
MAC is defined as the alveolar concentration of an inhalant anesthetic that prevents purposeful movement in response to a supramaximal noxious stimulus in 50% of patients, making it an ED50.
Question 3: Which of the following conditions or interventions would DECREASE MAC (reduce the anesthetic requirement) of an inhalant agent?
- Hyperthermia
- Chronic alcohol consumption
- Opioid premedication (Correct answer)
- Hyperthyroidism
Correct answer: Opioid premedication
Opioid premedication provides MAC sparing by 20–40%, reducing the amount of inhalant required; hyperthermia, chronic alcohol use, and hyperthyroidism all increase MAC.
Question 4: Malignant hyperthermia is a rare, life-threatening complication of anesthesia. Which drug is the treatment of choice?
- Dantrolene (Correct answer)
- Acepromazine
- Diazepam
- Propranolol
Correct answer: Dantrolene
Dantrolene sodium blocks calcium release from the sarcoplasmic reticulum, directly treating the uncontrolled skeletal muscle hypermetabolism characteristic of malignant hyperthermia.
Question 5: During anesthesia, a dog develops frequent premature ventricular contractions (PVCs) visible on ECG. What is the FIRST-LINE pharmacologic treatment?
- Epinephrine IV bolus
- Lidocaine IV bolus (Correct answer)
- Atropine IV
- Dopamine CRI
Correct answer: Lidocaine IV bolus
Intravenous lidocaine is the first-line antiarrhythmic for ventricular arrhythmias (PVCs, ventricular tachycardia) in anesthetized dogs due to its rapid onset and favorable cardiac profile.
Question 6: Which inhalant anesthetic is associated with the GREATEST cardiovascular depression and sensitization of the myocardium to catecholamine-induced arrhythmias?
- Isoflurane
- Sevoflurane
- Desflurane
- Halothane (Correct answer)
Correct answer: Halothane
Halothane causes significant myocardial depression, decreased cardiac output, and sensitizes the heart to catecholamine-induced arrhythmias, making it the most cardiotoxic of the inhalants; it is rarely used in modern veterinary practice for this reason.
Question 7: A cat anesthetized with isoflurane develops bradycardia (HR 70 bpm). What is the MOST appropriate first step before administering any drug?
- Administer atropine IV immediately
- Lighten anesthetic depth and reassess all parameters (Correct answer)
- Begin a dopamine CRI
- Increase the oxygen flow rate
Correct answer: Lighten anesthetic depth and reassess all parameters
Before administering any drug, the appropriate first response is to lighten anesthetic depth and assess all parameters, as anesthetic-induced vagal tone and excessive depth are common reversible causes of bradycardia.
NAVLE Veterinary Anesthesia and Pain Management 2
A dog under isoflurane anesthesia has an end-tidal CO2 (ETCO2) reading of 62 mmHg.
What does this finding indicate?