Free DVM Doctor of Veterinary Medicine Anesthesia and Surgical Principles Questions and Answers — Questions and Answers
Question 1: The Minimum Alveolar Concentration (MAC) of an inhalant anesthetic is used to compare agents based on which characteristic?
- The speed of induction and recovery
- The degree of cardiovascular depression
- Potency (Correct answer)
- Solubility in the blood
Correct answer: Potency
Minimum Alveolar Concentration (MAC) is defined as the concentration of an inhaled anesthetic in the alveoli needed to prevent movement in 50% of subjects in response to a noxious stimulus. Therefore, it is a direct measure of the agent's potency. A lower MAC indicates a more potent anesthetic. Solubility (blood:gas partition coefficient) determines the speed of induction/recovery, and cardiovascular depression is a side effect, not the primary measure of potency.
Question 2: During a routine ovariohysterectomy on a healthy canine patient, the end-tidal CO2 (ETCO2) on the capnograph abruptly drops from a steady 40 mmHg to near 0 mmHg. The patient's other vital signs are initially unchanged. What is the MOST likely cause of this change?
- Severe hypoventilation
- Malignant hyperthermia
- Disconnection of the breathing circuit or esophageal intubation (Correct answer)
- A sudden increase in cardiac output
Correct answer: Disconnection of the breathing circuit or esophageal intubation
An abrupt drop of the ETCO2 reading to zero or near zero indicates a sudden lack of CO2 being delivered to the sensor. The most common mechanical causes are a disconnection of the endotracheal tube from the breathing circuit or an accidental esophageal intubation, both of which prevent expired gas from reaching the capnograph. Hypoventilation would cause ETCO2 to rise, while malignant hyperthermia would cause a rapid and profound increase in CO2 production and ETCO2.
Question 3: A surgeon requires a suture material for closing the linea alba of a 40kg dog undergoing an exploratory laparotomy. The ideal material should be absorbable but retain significant tensile strength for at least 4-6 weeks to accommodate the slow healing of this fascial tissue. Which of the following is the most appropriate choice?
- Polyglactin 910 (Vicryl)
- Polydioxanone (PDS) (Correct answer)
- Surgical Gut (Chromic)
- Silk
Correct answer: Polydioxanone (PDS)
Polydioxanone (PDS) is a synthetic, monofilament, absorbable suture known for its extended tensile strength retention. It retains approximately 50-70% of its strength at 4 weeks, making it ideal for slow-healing tissues like the linea alba. Polyglactin 910 and Surgical Gut lose their strength too quickly for this application. Silk is non-absorbable and its multifilament nature can increase the risk of infection.
Question 4: A 9-year-old feline patient with known hypertrophic cardiomyopathy (HCM) requires anesthesia for multiple dental extractions. Which of the following drugs should be used with extreme caution or avoided as part of the anesthetic protocol due to its sympathomimetic effects, which increase heart rate and myocardial oxygen demand?
- Buprenorphine
- Meloxicam
- Lidocaine (as a dental block)
- Ketamine (Correct answer)
Correct answer: Ketamine
Ketamine causes a release of catecholamines, leading to sympathomimetic effects such as increased heart rate, blood pressure, and myocardial oxygen demand. These effects can be detrimental in a cat with hypertrophic cardiomyopathy (HCM), a condition characterized by a thickened, stiff ventricle where increased heart rate can worsen diastolic dysfunction and potentially exacerbate outflow tract obstruction. Buprenorphine, meloxicam (with care), and local lidocaine are generally considered safer choices.
Question 5: While monitoring a 7-year-old dog under isoflurane anesthesia for a mass removal, you note the mean arterial pressure (MAP) has dropped to 55 mmHg. The patient's heart rate is stable at 90 bpm and anesthetic depth is appropriate. What is the most appropriate FIRST step to manage this hypotension?
- Administer a bolus of an intravenous crystalloid solution. (Correct answer)
- Increase the isoflurane vaporizer setting.
- Start a constant rate infusion of dopamine.
- Administer a dose of atropine intravenously.
Correct answer: Administer a bolus of an intravenous crystalloid solution.
The most common cause of hypotension under inhalant anesthesia is vasodilation. The first and most appropriate step to correct this is to increase the intravascular volume by administering a bolus of an isotonic crystalloid fluid (e.g., 5-10 mL/kg). Increasing the isoflurane would worsen vasodilation and hypotension. Starting a pressor like dopamine is a second-line treatment if fluid therapy is ineffective. Atropine is an anticholinergic and is not indicated as the heart rate is not bradycardic.
Question 6: Which of the following methods is considered the gold standard for achieving sterility of common stainless steel surgical instruments, such as hemostats and scalpels, in a veterinary practice?
- Soaking in glutaraldehyde-based solution for 30 minutes.
- Wiping all surfaces with 70% isopropyl alcohol.
- Using a glass bead sterilizer for 45 seconds.
- Autoclaving with pressurized steam at 121°C (250°F) for 15 minutes. (Correct answer)
Correct answer: Autoclaving with pressurized steam at 121°C (250°F) for 15 minutes.
Steam sterilization (autoclaving) is the gold standard for sterilizing heat-tolerant surgical instruments. The combination of pressurized steam at a high temperature (a common standard is 121°C for at least 15 minutes) effectively kills all microorganisms, including resilient bacterial spores. Cold sterilization with glutaraldehyde is high-level disinfection but may not kill all spores, alcohol is a disinfectant, and glass bead sterilizers only sterilize the tips of instruments.
Free DVM Doctor of Veterinary Medicine Anesthesia and Surgical Principles Questions and Answers
The Minimum Alveolar Concentration (MAC) of an inhalant anesthetic is used to compare agents based on which characteristic?