What is the treatment for a patient with digoxin toxicity?

Treatment for Digoxin Toxicity

Digoxin-specific antibody fragments (digoxin-Fab) are the definitive first-line treatment for life-threatening digoxin toxicity, with response rates of 80-90% and dysrhythmia resolution typically occurring within 30-45 minutes. 1

Immediate Management Algorithm

Step 1: Discontinue Digoxin and Assess Severity

• Immediately stop digoxin administration in all cases 2, 3
• Initiate continuous cardiac rhythm monitoring 2, 4
• Obtain serum digoxin level, potassium, magnesium, calcium, and renal function 2, 5
• Assess for life-threatening manifestations: sustained ventricular arrhythmias, progressive bradyarrhythmias, heart block causing hemodynamic compromise, hyperkalemia >5.0-6.0 mEq/L, or cardiac arrest 1, 5, 4

Step 2: Administer Digoxin-Fab for Severe Toxicity

Digoxin-Fab should be administered immediately for any life-threatening manifestation, as it carries a Class 1 (strongest) recommendation from the American Heart Association. 1, 5

Indications for Digoxin-Fab:

• Life-threatening ventricular arrhythmias (ventricular tachycardia, ventricular fibrillation) 1, 3
• Progressive symptomatic bradyarrhythmias or heart block with hemodynamic compromise 1, 3
• Hyperkalemia >5.0-6.0 mEq/L 5, 4, 6
• Serum digoxin concentration >4 ng/mL with serious arrhythmias 2, 5
• Cardiac arrest from digoxin poisoning 1

Dosing Strategy:

• Acute poisoning: Administer 80 mg (2 vials) as initial bolus, repeat as needed based on clinical response 6
• Chronic toxicity: Start with 40 mg (1 vial), repeat after 60 minutes if symptoms persist 1, 6
• Imminent cardiac arrest: Consider empiric dose of 10-20 vials (400-800 mg) when immediate treatment is critical 5
• Each 40 mg vial binds approximately 0.5 mg of digoxin 1, 6
• Response typically occurs within 30-45 minutes; survival rate is 54% even in patients presenting with cardiac arrest 1

Step 3: Correct Electrolyte Abnormalities

Maintain serum potassium between 4.0-5.5 mEq/L, as hypokalemia potentiates digoxin toxicity even at therapeutic levels. 2, 3

• Administer oral or intravenous potassium for hypokalemia, monitoring ECG for peaked T waves 3
• Critical caveat: Do NOT give potassium in massive acute overdose with hyperkalemia, as this can be lethal 3
• Correct hypomagnesemia with intravenous magnesium sulfate, particularly for ventricular arrhythmias 1, 2, 4
• In massive overdose with life-threatening hyperkalemia, treat with glucose and insulin as temporizing measure while awaiting digoxin-Fab 3

Step 4: Temporizing Antiarrhythmic Measures (While Awaiting Digoxin-Fab)

For Bradydysrhythmias:

• Atropine may be reasonable as a temporizing measure, though evidence is limited to case reports with variable effects 1, 4
• Temporary transvenous pacing may be considered for refractory symptomatic bradycardia or heart block, but complications occur in 36% of cases 1, 4

For Ventricular Arrhythmias:

• Lidocaine or phenytoin may be reasonable until digoxin-Fab can be administered 1, 5, 4
• Bretylium was historically used but is no longer manufactured 1
• Intravenous magnesium is often administered for ventricular arrhythmias 2, 4

Step 5: Gastrointestinal Decontamination (Acute Ingestion Only)

• Administer activated charcoal if ingestion occurred within 2 hours and patient is alert with intact airway 3, 7
• Do NOT induce emesis or attempt gastric lavage if patient is obtunded or has toxic manifestations, as vagal stimulation can worsen arrhythmias 3
• Multiple-dose activated charcoal (MDACID) can enhance elimination through interruption of enterohepatic recirculation 8, 9

Management of Mild Toxicity

For patients without life-threatening manifestations:

• Discontinue digoxin and monitor cardiac rhythm for 24-48 hours 2, 5
• Correct electrolyte abnormalities (potassium, magnesium) 2, 3
• Recheck digoxin level in 24-48 hours to confirm declining trend 5
• Digoxin-Fab is NOT indicated for mild, asymptomatic toxicity 1, 2

Interventions That Do NOT Work

Hemodialysis, hemofiltration, hemoperfusion, and plasmapheresis are NOT recommended for digoxin removal due to its large volume of distribution (5-10 L/kg). 1, 4

The only exception is life-threatening hyperkalemia in massive overdose when digoxin-Fab is unavailable, though dialysis removes potassium, not digoxin 3

Critical Pitfalls to Avoid

• Never administer calcium in digoxin toxicity, as hypercalcemia sensitizes the myocardium to digoxin and can precipitate fatal arrhythmias 2
• Avoid potassium supplementation in massive acute overdose with hyperkalemia, as this worsens toxicity 3
• Do not rely on serum digoxin levels after digoxin-Fab administration, as levels become unreliable due to Fab-bound digoxin 1, 5, 4
• Monitor for rebound toxicity after digoxin-Fab, as both digoxin and digoxin-Fab have prolonged half-lives (>100 hours in renal failure) 6
• Watch for hypokalemia after digoxin-Fab, as potassium shifts back intracellularly once digoxin is neutralized 1, 4, 6

Post-Treatment Monitoring

• Monitor cardiac rhythm continuously for at least 24-48 hours 5
• Check potassium levels frequently, as they can shift dramatically after digoxin-Fab 1, 5
• Monitor for exacerbation of heart failure or increased ventricular rate in atrial fibrillation (uncommon adverse effects of digoxin-Fab) 4, 6
• Allergic reactions to digoxin-Fab are rare 4, 6

Reinitiation of Digoxin Therapy

If digoxin must be restarted after toxicity resolves:

• Use lower maintenance doses (0.125 mg daily or every other day) 2
• Target therapeutic serum concentration of 0.5-0.9 ng/mL 2, 5
• Avoid loading doses to minimize recurrence risk 2
• Address risk factors: correct electrolyte abnormalities, adjust for renal dysfunction, review drug interactions (amiodarone, clarithromycin, erythromycin, verapamil, quinidine) 2