Chapter 46: Vasodilators Flashcards
What is the action of Hydralazine? What are its uses?
Action: Dilation of arterioles.
Uses: essential hypertension, hypertensive crisis, and heart failure.
What is the action/use of Nitroglycerin?
Action: VSM to promote vasodilation, acts primarily on veins.
Uses: Stable and Unstable angina pectoris, IV nitroglycerin is used in the control of perioperative blood pressure, controlled hypotension during surgery, and treatment of heart failure.
What is the action/use of Sodium Nitroprusside?
Action: Arteriole and venous dilation.
Uses: hypertensive emergencies, producing controlled hypotension during surgery.
Which drug is most effective and most commonly used in hypertensive emergencies?
Sodium Nitroprusside is most commonly used in hypertensive emergencies.
What is orthostatic hypotension? What is reflex tachycardia? What instructions might be given to minimize either of these effects?
Orthostatic Hypotension: a drop in blood pressure when changing from supine or seated position to a standing position. This is caused by relaxation of the smooth muscles in veins.
Reflex tachycardia: The dilation of arterioles and veins that results in a drop in blood pressure; the brain signals the heart to increase rate to compensate.
Instructions: Make positional changes slowly. Pretreatment with a beta blocker prior to administration of vasodilators to reduce risk of reflex tachycardia.
Which vessels are capacitance vessels? Which are resistance vessels?
Capacitance vessels: Veins
Resistance vessels: Arteries
What would happen to cardiac output if we dilated capacitance vessels? What impact would this have on the oxygen demands of the heart?
When capacitance vessels (veins) are dilated filling of the heart (preload) would DECREASE. The oxygen demands of the heart would also DECREASE.
What happens when resistance vessels are dilated?
Dilations of resistance vessels (arteries) would result in INCREASED tissue perfusion.
What is a side effect of the vasodilators that occurs especially when they are infused too fast?
An increase in blood volume may occur if vasodilators are used long term or infused too fast. The kidneys signal the adrenal glands to secrete increased ALDOSTERONE which acts on the kidney to retain sodium and water. Vasodilators decrease blood flow to the kidney and reduce GFR, which results in an increase of blood volume expansion.
