A patient was admitted to the intensive care unit with cardiogenic shock and a blood pressure of 78/38. Which vasopressor medication does the nurse identify as the first-line treatment for cardiogenic shock?
Dopamine
Norepinephrine
Epinephrine
Vasopressin (Pitressin)
The Correct Answer is B
Choice A rationale:
Dopamine was once considered a first-line vasopressor for cardiogenic shock. However, recent studies have shown that it is associated with increased mortality compared to norepinephrine.
Dopamine has dose-dependent effects on dopamine receptors, beta receptors, and alpha receptors. At low doses (1-5 mcg/kg/min), it primarily stimulates dopamine receptors, leading to renal vasodilation and increased urine output. At moderate doses (5-10 mcg/kg/min), it stimulates beta receptors, resulting in increased heart rate and contractility. At high doses (>10 mcg/kg/min), it stimulates alpha receptors, causing vasoconstriction.
The main concern with dopamine is its potential to cause arrhythmias, particularly at higher doses. This is due to its effects on beta receptors, which can increase heart rate and myocardial oxygen demand.
Additionally, dopamine can cause tachyphylaxis, meaning that its effects can diminish over time, requiring higher doses to achieve the same effect.
Choice B rationale:
Norepinephrine is a potent alpha-adrenergic agonist that causes vasoconstriction, leading to an increase in blood pressure. It has minimal effects on beta receptors, so it is less likely to cause tachycardia and arrhythmias compared to dopamine.
Norepinephrine also has some inotropic effects, meaning that it can increase the strength of contraction of the heart muscle.
Studies have shown that norepinephrine is associated with improved survival rates in patients with cardiogenic shock compared to dopamine.
It is generally well-tolerated, with the most common side effects being hypertension and peripheral vasoconstriction.
Choice C rationale:
Epinephrine is a potent alpha- and beta-adrenergic agonist that causes vasoconstriction, increased heart rate, and increased contractility.
It is typically used as a second-line agent in cardiogenic shock, after norepinephrine has failed to achieve adequate blood pressure.
Epinephrine can cause significant tachycardia and arrhythmias, so it should be used with caution in patients with underlying heart disease.
Choice D rationale:
Vasopressin is a hormone that causes vasoconstriction by acting on V1 receptors in vascular smooth muscle. It is sometimes used as an adjunct to norepinephrine in patients with refractory cardiogenic shock.
Vasopressin has the potential to cause coronary vasoconstriction, so it should be used with caution in patients with coronary artery disease.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Rationale for Choice A:
It is not recommended to always consume levothyroxine with food. In fact, food can interfere with the absorption of levothyroxine, leading to decreased efficacy of the medication.
Consuming levothyroxine with food can decrease its absorption by up to 30%, which can significantly impact its ability to manage hypothyroidism symptoms.
Certain foods, such as those high in fiber, calcium, or iron, can be particularly problematic, as they can bind to levothyroxine in the gut and further reduce its absorption.
While taking levothyroxine with a small amount of food may be necessary for some individuals who experience gastrointestinal side effects, it's generally recommended to take it on an empty stomach for optimal absorption.
Rationale for Choice B:
Milk is not an ideal beverage to take with levothyroxine, as it can also interfere with absorption. Milk contains calcium, which can bind to levothyroxine and reduce its absorption.
It's best to avoid consuming milk or other calcium-rich beverages within a few hours of taking levothyroxine.
Rationale for Choice C:
Similar to milk, juice and crackers are not ideal choices to take with levothyroxine.
Juice, especially those high in acidity, can affect the absorption of levothyroxine in the gut.
Crackers, often made with refined grains, can be high in fiber, which can also interfere with absorption.
Rationale for Choice D:
Taking levothyroxine on an empty stomach, typically 30-60 minutes before breakfast, is generally recommended to ensure optimal absorption.
This allows the medication to be absorbed more efficiently in the small intestine without being affected by the presence of food.
By taking levothyroxine on an empty stomach, patients can maximize its effectiveness in treating hypothyroidism.
Correct Answer is C
Explanation
Choice A rationale:
Hypertension is not a primary contraindication for mannitol use. While it's important to monitor blood pressure during mannitol administration, it's not the most concerning factor in this scenario.
Mannitol can even be used cautiously in hypertensive patients with conditions like intracranial hypertension or acute renal failure, where its benefits may outweigh the potential risks of exacerbating hypertension.
Choice B rationale:
Mannitol is actually indicated for the treatment of increased intracranial pressure (ICP). It works by drawing fluid from the brain tissues into the bloodstream, thereby reducing pressure within the skull.
Therefore, a patient with ICP would not be a concern for mannitol administration; rather, they would be a potential candidate for its use.
Choice D rationale:
While fluid volume overload can be a concern with mannitol use, it's typically managed with careful monitoring and fluid restriction.
The more significant concern in this scenario is congestive heart failure (CHF).
Choice C rationale:
Mannitol is contraindicated in patients with congestive heart failure (CHF). Here's why:
Increased Circulating Volume: Mannitol is an osmotic diuretic, meaning it draws fluid from the tissues into the bloodstream, increasing circulating blood volume. This can overload the already compromised heart in CHF patients, leading to worsening heart failure and pulmonary edema.
Elevated Blood Pressure: Mannitol can also cause a transient increase in blood pressure due to its osmotic effects. This can further strain the heart and worsen CHF symptoms.
Renal Impairment: CHF patients often have impaired renal function, which can reduce their ability to excrete mannitol effectively. This can lead to fluid retention and electrolyte imbalances, further complicating CHF management.
In summary, administering mannitol to a patient with CHF could potentially lead to:
Exacerbation of heart failure symptoms Pulmonary edema
Worsening renal function Electrolyte imbalances Increased risk of mortality
Therefore, it's crucial to avoid mannitol use in patients with CHF and to closely monitor fluid status and electrolytes in those who must receive it for other indications.
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