Digoxin

Summary

This video provides an in-depth, NCLEX-focused overview of digoxin, a cardiac glycoside used to treat systolic heart failure and arrhythmias like atrial fibrillation. It explains how digoxin increases heart contractility by inhibiting the sodium-potassium ATPase pump, leading to higher intracellular calcium, while also slowing heart rate and AV conduction via the vagus nerve. The video covers signs of toxicity—including gastrointestinal, neurological, visual, and cardiac effects—high-risk patients, therapeutic ranges, and essential nursing interventions such as monitoring apical pulse and lab values. Practical tips on patient education and toxicity management, including the use of Digibind, are also highlighted.

Takeaways

• 💊 Digoxin, also known as Lanoxin or 'Dig,' is a cardiac glycoside used primarily for mild systolic heart failure and certain arrhythmias like atrial fibrillation or flutter.
• 🫀 Digoxin works by inhibiting the sodium-potassium ATPase pump in myocardial cells, which indirectly increases intracellular calcium and sodium, leading to stronger heart contractions (positive inotropic effect).
• ⏱️ It also has a negative chronotropic effect (slows heart rate) and a negative dromotropic effect (slows AV node conduction) through vagus nerve stimulation.
• 📈 By increasing stroke volume and controlling heart rate, digoxin helps improve cardiac output in patients with heart failure or arrhythmias.
• ⚠️ Common signs of digoxin toxicity include gastrointestinal issues (nausea, vomiting, anorexia), neurological symptoms (fatigue, confusion), visual disturbances (blurred vision, yellow-green halos), and new or worsening arrhythmias.
• 🧪 Patients most at risk for digoxin toxicity include those with renal impairment, low potassium (<3.5 mEq/L), high calcium (>10.2 mg/dL), or low magnesium (<1.5 mg/dL), especially if on diuretics like furosemide.
• 📊 Therapeutic digoxin levels are typically 0.5–2 ng/mL; levels above 2 ng/mL indicate toxicity, which requires holding the dose, notifying the healthcare provider, and possibly administering digoxin-specific antibody (Digibind).
• 💓 Before administering digoxin, always assess the apical pulse for a full minute. Hold the medication if the heart rate is below 60 bpm in adults, 70 bpm in children, or 90–110 bpm in infants.
• 🩺 Ongoing monitoring should include regular blood tests for digoxin levels, electrolytes (potassium, calcium, magnesium), and kidney function (BUN and creatinine).
• 📌 Patient education is crucial: teach patients not to double doses if they miss one, recognize signs of toxicity, and seek medical attention promptly if symptoms arise.

Q & A

What class of medication is Digoxin, and what are its primary clinical uses?

Digoxin is a cardiac glycoside primarily used to improve heart contractility in patients with systolic heart failure and to control heart rate in arrhythmias such as atrial fibrillation and atrial flutter.

How does Digoxin affect the sodium-potassium ATPase pump in myocardial cells?

Digoxin inhibits the sodium-potassium ATPase pump, reducing the pumping of sodium out of the cell and potassium into the cell. This leads to increased intracellular sodium.

Explain the role of the sodium-calcium exchanger in Digoxin’s mechanism of action.

The sodium-calcium exchanger normally moves sodium in and calcium out. When intracellular sodium increases due to Digoxin, less calcium is pumped out, leading to increased intracellular calcium, which enhances myocardial contractility.

What are the key physiological effects of Digoxin on the heart?

Digoxin has a positive inotropic effect (increases contractility), a negative chronotropic effect (slows heart rate), and a negative dromotropic effect (slows conduction through the AV node).

List common signs of Digoxin toxicity.

Signs include gastrointestinal symptoms (nausea, vomiting, anorexia), neurological symptoms (fatigue, confusion), visual disturbances (blurred vision, yellow-green halos), and cardiac arrhythmias.

Which patients are most at risk for Digoxin toxicity?

Patients with renal failure, electrolyte imbalances (hypokalemia, hypercalcemia, hypomagnesemia), and those taking diuretics, particularly loop diuretics like furosemide, are at higher risk.

What is the therapeutic range for Digoxin, and at what level is it considered toxic?

The therapeutic range is 0.5–2 ng/mL, and levels above 2 ng/mL are considered toxic according to NCLEX guidelines.

What steps should a nurse take if a patient shows signs of Digoxin toxicity?

The nurse should hold the medication, notify the healthcare provider, assess the patient for arrhythmias and other symptoms, and administer the antidote digoxin immune fab if ordered.

How should a nurse assess the apical pulse before giving Digoxin?

The apical pulse should be measured at the 5th intercostal space, midclavicular line, for a full 60 seconds. The medication should be held if the pulse is <60 bpm in adults, <70 bpm in children, or <90–110 bpm in infants.

Why should a patient not double a missed dose of Digoxin?

Doubling a missed dose can increase the risk of toxicity. Patients should take only the scheduled dose at the next regular time.

What blood tests are important for monitoring patients on Digoxin?

Blood tests should include Digoxin levels, electrolytes (potassium, calcium, magnesium), and kidney function (BUN, creatinine) to prevent toxicity and ensure safe therapy.

How does Digoxin increase cardiac output in patients with heart failure?

By increasing intracellular calcium, Digoxin enhances myocardial contractility (positive inotrope), which increases stroke volume. Combined with a controlled heart rate, this improves cardiac output.