When administering an alpha blocker for the first time, it is most important for the nurse to assess the patient for the development of what adverse effect?
Renal failure.
Hypotension.
Blood dyscrasia.
Dysrhythmias.
The Correct Answer is B
Choice A rationale
Alpha blockers primarily exert their effects on the vascular smooth muscle by blocking alpha-1 adrenergic receptors. This action leads to vasodilation, which lowers blood pressure. They do not have a direct mechanism of action that would precipitate acute renal failure upon first dose administration. Renal function, while monitored, is not the most immediate or common adverse effect to assess for.
Choice B rationale
Alpha-1 adrenergic receptors, when blocked by alpha blockers, cause vasodilation of both arteries and veins. This leads to a decrease in peripheral vascular resistance and venous return, causing a significant drop in blood pressure. This effect, known as orthostatic hypotension or "first-dose phenomenon," is a common and critical adverse effect to assess for, as it can cause dizziness and fainting.
Choice C rationale
Blood dyscrasias, or disorders involving the cellular components of blood, are not a typical or immediate adverse effect associated with the first administration of an alpha blocker. While some medications can cause these rare side effects over long-term use, the acute and most common concern with the initial dose is related to its cardiovascular effects on blood pressure.
Choice D rationale
While alpha blockers can indirectly affect the heart rate through baroreceptor reflexes in response to hypotension, they are not typically associated with the direct induction of significant dysrhythmias as a primary adverse effect upon first administration. The immediate and most profound hemodynamic effect is the peripheral vasodilation and subsequent hypotension, which takes precedence in initial assessment.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
Metoprolol is a beta-blocker that reduces myocardial oxygen demand by decreasing heart rate, contractility, and blood pressure. While it is effective for long-term management and prevention of angina, it is not the preferred choice for immediate relief of an acute anginal attack due to its slower onset of action. Its primary role is prophylaxis.
Choice B rationale
Nitroglycerin is a potent vasodilator that works by relaxing vascular smooth muscle, primarily affecting veins, which reduces venous return (preload) and myocardial oxygen demand. It also dilates coronary arteries, increasing blood flow and oxygen supply to the heart muscle. Its rapid onset makes it the drug of choice for acute angina.
Choice C rationale
Amlodipine is a calcium channel blocker that works by inhibiting the influx of calcium into vascular smooth muscle and myocardial cells, causing vasodilation and reduced peripheral resistance. Although it is used for the long-term management of chronic stable angina, its onset of action is not rapid enough for immediate relief during an acute attack.
Choice D rationale
Aspirin is an antiplatelet agent that works by irreversibly inhibiting cyclooxygenase (COX) enzyme, preventing the formation of thromboxane A2. This reduces platelet aggregation and clot formation, which is crucial in preventing myocardial infarction in the setting of unstable angina, but it does not provide immediate relief from chest pain.
Correct Answer is B
Explanation
Choice A rationale
Digoxin is a cardiac glycoside that increases myocardial contractility and stroke volume, leading to improved cardiac output. It primarily affects the heart's pumping ability and heart rate, but it is not the main drug used to reduce both preload and afterload. Its role is more to manage symptoms of heart failure and improve cardiac output.
Choice B rationale
ACE inhibitors (e.g., lisinopril) work by blocking the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor. This leads to vasodilation, which decreases both systemic vascular resistance (afterload) and venous pressure (preload), making them a cornerstone for treating heart failure and reducing the workload on the heart.
Choice C rationale
Beta-blockers (e.g., carvedilol) block the effects of epinephrine and norepinephrine on beta receptors, leading to a decrease in heart rate and contractility. This reduces myocardial oxygen demand and can improve ventricular remodeling over time in heart failure, but they do not primarily reduce both preload and afterload in the same way as ACE inhibitors.
Choice D rationale
Diuretics (e.g., furosemide) work by increasing the excretion of sodium and water from the body, which reduces blood volume. This primarily reduces preload (volume returned to the heart) and is used to manage symptoms like edema and congestion, but it is not as effective at reducing afterload as ACE inhibitors.
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