CCP Vasoactive Drug Pharmacology 3 — Questions and Answers
Question 1: Which vasoactive drug is the first-line agent recommended by AHA/ACC for vasoplegic syndrome following cardiac surgery?
- Epinephrine
- Vasopressin (Correct answer)
- Phenylephrine
- Milrinone
Correct answer: Vasopressin
Vasopressin is recommended as a first-line agent for vasoplegic syndrome because it restores vascular tone via V1 receptors in patients refractory to catecholamines.
Question 2: The alpha-to-beta receptor activity ratio of epinephrine shifts at higher doses to primarily:
- Increase beta-2 activity causing bronchodilation
- Increase alpha-1 activity causing vasoconstriction (Correct answer)
- Increase beta-1 activity causing tachycardia only
- Decrease all adrenergic receptor stimulation
Correct answer: Increase alpha-1 activity causing vasoconstriction
At high doses, epinephrine's alpha-1 agonist activity predominates, overriding beta-2 vasodilation and causing significant systemic vasoconstriction.
Question 3: Nitroglycerin's preferential vasodilation of venous capacitance vessels over arterioles makes it most useful for treating:
- Systemic hypotension
- Pulmonary hypertension
- Acute pulmonary edema with elevated preload (Correct answer)
- Low cardiac output syndrome
Correct answer: Acute pulmonary edema with elevated preload
By dilating venous capacitance vessels, nitroglycerin reduces preload and ventricular filling pressures, making it ideal for acute pulmonary edema.
Question 4: A patient on CPB receives phenylephrine to treat hypotension. The expected hemodynamic response includes:
- Increased heart rate and cardiac output
- Increased SVR with reflex bradycardia (Correct answer)
- Decreased SVR with increased heart rate
- Increased contractility with unchanged SVR
Correct answer: Increased SVR with reflex bradycardia
Phenylephrine is a pure alpha-1 agonist that increases SVR; the resulting rise in blood pressure triggers a baroreceptor-mediated reflex bradycardia.
Question 5: Which of the following best describes tachyphylaxis as it relates to continuous nitroglycerin infusion?
- Increased drug toxicity with repeated dosing
- Progressive loss of hemodynamic response over 24–48 hours (Correct answer)
- Allergic sensitization after first exposure
- Paradoxical hypertension upon discontinuation
Correct answer: Progressive loss of hemodynamic response over 24–48 hours
Continuous nitroglycerin infusion leads to tachyphylaxis—diminished vasodilatory response—within 24–48 hours due to depletion of sulfhydryl groups needed for nitric oxide generation.
Question 6: During CPB, isoproterenol is occasionally used to treat which specific condition?
- High SVR with normal cardiac output
- Sinus bradycardia or heart block requiring chronotropy (Correct answer)
- Pulmonary hypertension refractory to milrinone
- Hypertensive crisis during aortic cross-clamp
Correct answer: Sinus bradycardia or heart block requiring chronotropy
Isoproterenol, a non-selective beta agonist, is used for chronotropy in bradycardia or heart block when temporary pacing is unavailable or insufficient.
Question 7: Inhaled nitric oxide (iNO) is used perioperatively primarily to reduce:
- Systemic vascular resistance
- Left ventricular afterload
- Pulmonary vascular resistance (Correct answer)
- Coronary vasospasm
Correct answer: Pulmonary vascular resistance
Inhaled NO selectively dilates the pulmonary vasculature by activating soluble guanylate cyclase in pulmonary smooth muscle, reducing PVR without causing systemic hypotension.
CCP Vasoactive Drug Pharmacology 3
Which vasoactive drug is the first-line agent recommended by AHA/ACC for vasoplegic syndrome following cardiac surgery?