Lilley Chapter 25: Heart Failure Drugs Flashcards
(13 cards)
A patient about to receive his morning dose of digoxin has an apical pulse of 70 beats per minute. What should the nurse do?
a. Administer the dose
b. Withhold the dose and notify the physician.
c. Notify the physician and monitor the patient’s vital signs.
d. Recheck the pulse, making sure to count for 1 full minute.
a. Administer the dose
The dose should only be held if the apical pulse is 60 beats per minute or less or higher than 120 beats per minute.
Apical pulse < 60 bpm?
Put the syringe down, Dr. Doom. This is a classic sign of bradycardia, and digoxin can make it worse.
• Digoxin slows the heart rate. Giving it when the rate’s already low can lead to:
• Severe bradycardia
• Heart block (aka your heart giving up on teamwork)
• Syncope (fainting, aka the patient dramatically flopping like a Victorian ghost)
• Worst case: asystole aka flatline aka “No more heart party”
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Now, what if the pulse is too high?
Apical pulse > 120 bpm?
You’re probably looking at tachycardia, and that could signal:
• A possible underlying condition (like fever, arrhythmia, or drug toxicity)
• Or that the patient’s just not stable enough for digoxin at that moment
Giving digoxin then could cause:
• Worsened arrhythmias—it slows the AV node conduction, but that’s not always helpful if something else is already going haywire
• Digoxin toxicity—especially in the elderly or renally impaired, which is basically 80% of patients in med-surg
The nurse is assessing the patient before administration of cardiac glycoside. Which condition can predispose a patient to digitalis toxicity?
a. Hypokalemia
b. Hyperkalemia
c. Hypocalcemia
d. Heart failure
a. Hypokalemia
First up: What is digoxin?
Digoxin is a cardiac glycoside (fancy term for “heart drug”) that helps the heart pump better.
It slows the heart down and makes each beat stronger—like a motivational coach for your left ventricle.
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What is digitalis toxicity?
That’s when there’s too much digoxin in the body and your heart goes, “Uhh, I can’t even,” and starts misfiring like a cheap sparkler.
Signs of toxicity include:
• Nausea, vomiting
• Blurry vision (hello, yellow halos)
• Confusion
• Irregular heart rhythms (cue dramatic EKG music)
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Now, what the heck is hypokalemia?
“Hypo” = low
“Kalemia” = potassium in the blood
So, hypokalemia = low potassium
And here’s where the tea gets hot:
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Why does low potassium cause digoxin toxicity?
Digoxin and potassium basically compete for the same parking spot on the cells of your heart.
So if potassium is low, digoxin strolls in and takes over like a power-hungry intern who just found out the manager’s on vacation.
Result? More digoxin binds to heart cells → Higher risk of toxic effects → Your heart throws a tantrum.
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Why not the other options?
• b. Hyperkalemia (high potassium): This actually reduces digoxin’s effect, not worsen it. It’s a different kind of heart risk, but not the digoxin drama.
• c. Hypocalcemia (low calcium): Doesn’t affect digoxin toxicity directly. Wrong party.
• d. Heart failure: Sure, the reason you might be taking digoxin, but not the reason you overdose on it.
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Big Takeaway:
Low potassium = high digoxin danger
Check potassium before giving digoxin, or your patient might go into rhythm roulette.
“DIG the grave if the K is too low
The nurse who is assessing a patient who is receiving IV digitalis recognizes that the drug has a negative chronotropic effect. How is a negative chronotropic effect evident in a patient?
a. By an increased heart rate.
b. By a decreased heart rate.
c. By decreased conduction
d. By increased ectopic beats
b. B y a decreased heart rate.
What is a chronotropic effect?
Let’s break the word down:
• Chrono = time (like a chronological timeline)
• Tropic = affecting
So in the land of cardiology, a chronotropic effect = how a drug affects heart rate over time.
Simple.
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Now for the juicy part: positive vs. negative
• Positive chronotropic effect = increases heart rate (your heart speeds up)
• Negative chronotropic effect = decreases heart rate (your heart chills out)
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So, what is digitalis (aka digoxin) doing here?
Digoxin has a negative chronotropic effect—it slows down the heart rate. That’s one of the reasons it’s given for heart failure and atrial fibrillation: it calms your racing heart so it can pump more effectively without flailing.
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Back to the question:
“How is a negative chronotropic effect evident in a patient?”
• a. Increased heart rate → WRONG, that would be positive • b. Decreased heart rate → CORRECT, textbook digoxin move • c. Decreased conduction → That’s more of a dromotropic effect (yep, that’s a real word too. Sorry.) • d. Increased ectopic beats → That’s a sign of arrhythmia or digoxin toxicity, not the regular expected effect
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TL;DR:
Chronotropic = heart rate.
Negative chronotropic = slower heart rate.
Digoxin does that.
A patient has been taking digoxin at home but has developed toxicity. The physician has ordered digoxin immune Fab (digibind). The patient asks the nurse why the medication has been changed. Which is the nurse’s best response?
a. “It works faster than digoxin”
b. “It is safer than digoxin and can be taken orally”
c. “It helps to convert the fibrillating atria to a more normal rhythm”
d. “This new drug is an antidote to digoxin and will help to lower the blood levels”
d. “This new drug is an antidote to digoxin and will help to lower the blood levels”
What is Digibind?
Digibind is basically a monoclonal antibody fragment—a lab-made protein that’s designed to specifically bind to digoxin like it’s playing Pokémon and digoxin is the one card it’s obsessed with catching.
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What does it do?
It binds to free digoxin in the bloodstream, forming inactive complexes. Once bound, the digoxin can no longer:
• Bind to the sodium-potassium ATPase pump
• Mess with potassium levels
• Cause bradycardia, nausea, visual halos, and all the other fun symptoms of toxicity
Instead, the immune Fab-digoxin complex gets filtered out by the kidneys and excreted like yesterday’s bad decisions.
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In short:
Digibind = “Digoxin sponge.”
It mops up the extra digoxin so it can’t do more harm, and helps bring the blood levels down fast.
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When do we use it?
• Life-threatening digoxin toxicity
• Serious arrhythmias caused by digoxin
• Serum digoxin level > 10 ng/mL (acute) or > 6 ng/mL (chronic)
• Hyperkalemia + digoxin toxicity = medical panic mode
A patient has been placed on a milrinone infusion as part of the therapy for end-stage heart failure. What risk should the nurse keep in mind while assessing this patient during the infusion?
a. Hypotension
b. Hyperkalemia
c. Hypertension
d. Decreased urine output
a. Hypotension
Milrinone is basically the Red Bull of cardiac meds: it amps up contractility (positive inotrope) and relaxes the vascular smooth muscle (vasodilator), so the heart can pump more effectively. But while it’s helping the heart pretend it’s in better shape than it is, it also drops systemic vascular resistance like it’s hot — leading to hypotension.
So yes, it makes your heart pump harder while making your arteries wider.
A patient with atrial fibrillation has been started on digoxin, and 1 week later a digoxin level is drawn. Which result is within the normal therapeutic levels for digoxin?
a. 0.1 - 0.6
b. 0.7 - 1.5
c. 2.0 - 2.5
d. 2.5 to 3.0
c. 2.0 - 2.5
According to Lilley text: The digoxin therapeutic window is between 0.8 and 2.0.
The correct therapeutic range for digoxin is typically 0.8 to 2.0 ng/mL. Some sources may say 0.5 to 2.0, depending on the clinical setting, but anything above 2.0 risks toxicity—think nausea, confusion, and funky yellow vision (digoxin is weird like that).
So even though the question marks 2.0–2.5 as correct, that would actually be pushing it. In practice, 1.0–1.5 is often considered a sweet spot
Which medication results in a drug interaction if given to a patient taking digitalis?
a. Acetylsalicylic acid
b. Acetaminophen
c. quinidine sulphate
d. Vitamin K
c. quinidine sulphate
The most common drug-drug interactions with digoxin are with amiodarone, quinidine sulphate, and verapamil. These three drugs can increase digoxin levels by 50%.
it decreases digoxin clearance, so the blood levels go way up. And since digoxin toxicity is a real drama queen (visual disturbances, nausea, arrhythmias), that’s a big deal.
A patient is beginning digoxin therapy. Which food should the nurse tell this patient to avoid when taking the digoxin dose?
a. Cooked vegetables
b. Canned fruits
c. Fried foods
d. Bran muffins
d. Bran muffins
Bran muffins, in large amounts may decrease the absorption of oral digitalis drugs.
The nurse is assessing a patient before administration of cardiac glycoside. Which laboratory result can increase the toxicity of the drug?
a. Potassium level of 2.8 mmol/L
b. Potassium level of 4.9 mmol/L
c. Sodium level of 140 mmol/L
d. Calcium level of 10 mmol/L
a. Potassium level of 2.8 mmol/L
Hypokalemia increases the chance of digitalis toxicity
The nurse is administering the phosphodiesterase inhibitor milrinone. What is the drug’s positive inotropic effect?
a. Increased heart rate.
b. Increased blood vessel dilation.
c. Increased force of cardiac contraction
d. Increased conduction of electrical impulses across the heart.
c. Increased force of cardiac contraction
Which condition predisposes a patient to digitalis toxicity?
a. Hypercalcemia and advanced age.
b. Hyperthyroidism and liver dysfunction
c. Ventricular fibrillation and hyperkalemia
d. Dysrhythmias and hypernatremia
a. Hypercalcemia and advanced age.
Which assessment result is the most important indicator of an exacerbation of heart failure?
a. Increased weight
b. Hypokalemia
c. Increased pulse
d. Increased oxygen saturation
a. Increased weight
Patients should be weighed at the same time each day with the same amount of clothing because weight is an important indicator of fluid volume overload or the exacerbation of heart failure.
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