Which medication is commonly used to reduce preload and afterload in heart failure?
Digoxin.
ACE inhibitors.
Beta-blockers.
Diuretics.
The Correct Answer is B
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale
When mixing insulin lispro (rapid-acting) with NPH (intermediate-acting), it is a standard and crucial procedure to draw the clear rapid-acting insulin first, followed by the cloudy NPH insulin. This is to prevent the contamination of the rapid-acting vial with the NPH suspension, which could alter the rapid-acting insulin's predictable onset and peak.
Choice B rationale
While unopened insulin vials should be stored in the refrigerator, the patient's current in-use vials can be stored at room temperature for up to 28 days to make injections more comfortable. Injecting cold insulin can cause discomfort and lipohypertrophy at the injection site. However, the refrigerator is where all unopened vials are stored.
Choice C rationale
Shaking the insulin for a full minute is not recommended. Vigorous shaking can cause foaming and bubble formation, which can lead to inaccurate dosing. NPH insulin, a suspension, should be gently rolled between the palms to ensure uniform mixing and proper suspension of the particles, which prevents clumping and allows for accurate dosing.
Choice D rationale
Administering an injection at a 30-degree angle is not standard practice for subcutaneous insulin injections. Insulin is injected into the subcutaneous fat layer. A 90-degree angle is commonly used for most patients, and a 45-degree angle may be used for very thin individuals or for injections into the arms. A 30-degree angle is not correct.
Correct Answer is ["B","D"]
Explanation
Choice A rationale
A low therapeutic index indicates a small difference between the therapeutic dose and the toxic dose, not that low doses are ineffective. The therapeutic index is a ratio that compares the dose that produces a therapeutic effect to the dose that causes toxicity. Therefore, the low end of the dose range can still be therapeutic, but the therapeutic window itself is narrow.
Choice B rationale
Barbiturates have a low therapeutic index, which means there is a narrow margin between the therapeutic and toxic drug concentrations. A small increase in dosage beyond the therapeutic range can lead to significant toxicity. This narrow therapeutic window necessitates close monitoring of patients to avoid adverse effects.
Choice C rationale
While barbiturates are indeed habit-forming and have a high potential for physical and psychological dependence, this characteristic is not what is meant by a "low therapeutic index.”. The low therapeutic index refers to the relationship between the effective dose and the toxic dose, not the potential for addiction.
Choice D rationale
A low therapeutic index signifies that the range between the minimum effective concentration and the minimum toxic concentration is narrow. This means the drug dosage must be carefully controlled and monitored to ensure it is effective without causing harmful side effects. Small dosing errors can lead to toxicity, highlighting the drug's narrow safe dosage range.
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