ABA Fundamentals & Core Concepts 3 — Questions and Answers
Question 1: The minimum alveolar concentration (MAC) of an inhalational anesthetic is DECREASED by:
- Hyperthermia and chronic alcohol use
- Hypothermia and opioid premedication (Correct answer)
- Hyperthyroidism and anxiety
- Young age and increased CNS stimulants
Correct answer: Hypothermia and opioid premedication
Hypothermia, opioids, barbiturates, benzodiazepines, advanced age, and acute alcohol intoxication all decrease MAC requirements.
Question 2: Which volatile anesthetic is MOST associated with nephrotoxicity due to inorganic fluoride production?
- Isoflurane
- Desflurane
- Sevoflurane (Correct answer)
- Halothane
Correct answer: Sevoflurane
Sevoflurane undergoes the greatest degree of biodegradation among modern volatile anesthetics, producing inorganic fluoride that can cause renal tubular dysfunction at very high exposures.
Question 3: In the context of anesthetic pharmacology, 'context-sensitive half-time' refers to:
- The half-life of a drug in hepatic disease
- The time for plasma concentration to decrease 50% after stopping an infusion of a given duration (Correct answer)
- The duration of action based on protein binding
- The time required to reach steady-state during continuous infusion
Correct answer: The time for plasma concentration to decrease 50% after stopping an infusion of a given duration
Context-sensitive half-time accounts for drug redistribution from peripheral compartments back to plasma after stopping an infusion, and varies with infusion duration.
Question 4: The pulmonary vascular resistance (PVR) is INCREASED by which condition?
- Alkalosis and hyperoxia
- Nitric oxide administration
- Hypoxia and hypercapnia (Correct answer)
- Calcium channel blockers
Correct answer: Hypoxia and hypercapnia
Hypoxic pulmonary vasoconstriction (HPV) and hypercapnia increase PVR by causing pulmonary arterial smooth muscle constriction.
Question 5: Which statement about succinylcholine is CORRECT?
- It is a competitive antagonist at nicotinic receptors
- Its effects can be reversed with neostigmine
- It causes fasciculations followed by flaccid paralysis (Correct answer)
- It has a prolonged duration in patients with elevated pseudocholinesterase
Correct answer: It causes fasciculations followed by flaccid paralysis
Succinylcholine depolarizes the motor end plate causing fasciculations, then produces flaccid paralysis due to phase I blockade as the end plate remains depolarized.
Question 6: Which monitoring parameter most directly reflects cerebral oxygenation during carotid endarterectomy?
- End-tidal CO2 monitoring
- Near-infrared spectroscopy (NIRS) or regional cerebral oximetry (Correct answer)
- Invasive arterial blood pressure
- Central venous pressure monitoring
Correct answer: Near-infrared spectroscopy (NIRS) or regional cerebral oximetry
Near-infrared spectroscopy (NIRS) measures regional cerebral oxygen saturation non-invasively by detecting the ratio of oxygenated to deoxygenated hemoglobin in brain tissue.
Question 7: Dead space ventilation (VD/VT) is INCREASED by which of the following?
- Pulmonary embolism and low cardiac output (Correct answer)
- Increased tidal volume and high PEEP
- Supine position and controlled ventilation
- Bronchospasm and pulmonary edema
Correct answer: Pulmonary embolism and low cardiac output
Pulmonary embolism obstructs blood flow to ventilated alveoli, creating alveolar dead space; low cardiac output similarly reduces perfusion relative to ventilation.
ABA Fundamentals & Core Concepts 3
The minimum alveolar concentration (MAC) of an inhalational anesthetic is DECREASED by: