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Digoxin

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Digoxin

Key Points

  • Digoxin is a cardiac glycoside that can improve contractility and help control rate/rhythm in selected pediatric cardiac conditions.
  • Digoxin is also used as second-line therapy in selected adult heart-failure or atrial-fibrillation contexts when safer alternatives are insufficient.
  • Therapeutic benefit in congenital-HF pathways includes improved forward flow and reduced pulmonary/systemic congestion burden.
  • Pediatric digoxin has a narrow safety margin; small dosing errors can cause severe dysrhythmia and death.
  • Adult heart-failure use is adjunctive after first-line optimization and often requires individualized loading-versus-maintenance planning.
  • In adults, a common pre-dose hold parameter is apical heart rate under 60 bpm unless a different provider order exists.
  • Digoxin reference serum range is commonly about 0.5-2 ng/mL; mortality risk may rise at higher concentrations (for example at or above about 1.2 ng/mL) in some cohorts.
  • In infants, hold parameters commonly include apical heart rate under 100 bpm before dosing unless provider order states otherwise.
  • Hypokalemia and hypomagnesemia increase digoxin-toxicity risk, especially when combined with diuretic therapy.
  • Digoxin immune fab is the antidote for life-threatening toxicity, including very high levels (for example about >6-10 ng/mL) with clinical instability; post-antidote monitoring should include worsening HF/AF and hypokalemia.

Mechanism of Action

Digoxin has a positive inotropic effect by increasing myocardial contractile force and a negative chronotropic/conduction effect by slowing atrioventricular node conduction. This combination can improve cardiac output while reducing excessive ventricular response in selected rhythm contexts.

Mechanistically, digoxin inhibits the sodium-potassium ATPase pump, increasing intracellular sodium and secondary calcium influx in cardiac myocytes, which strengthens contraction.

In pediatric heart-failure pathways, improved contractility and longer ventricular filling time can reduce blood backup in the lungs, improve systemic perfusion, and support renal perfusion.

Indications

  • Second-line treatment in selected adult heart-failure or atrial-fibrillation contexts.
  • Symptom management in selected pediatric heart-failure pathways.
  • Rate/rhythm support in provider-selected pediatric arrhythmia contexts.
  • Adjunct in congenital-heart-disease care plans when hemodynamic goals include improved perfusion and reduced congestion burden.

Dosing and Monitoring Context

Safety Focus

Use institution-specific pediatric protocols and exact provider orders; weight-based double-checks are mandatory before administration.

  • Loading phase (digitalization) may be ordered to rapidly reach therapeutic effect (for example total loading dose over about 24 hours in divided dosing).
  • Maintenance dosing is weight-based and often split into two daily doses.
  • Pediatric reference example used in congenital-HF pathways: loading about 20-40 mcg/kg over 24 hours, then maintenance about 8-10 mcg/kg/day in two divided doses (always follow current provider order/protocol).
  • Renal impairment requires dose reduction because clearance is decreased.
  • Serum digoxin levels are interpreted with timing context; levels are commonly drawn after adequate post-dose distribution interval.
  • Adult monitoring commonly uses a therapeutic range of about 0.8-2 ng/mL, with additional clinical correlation for toxicity signs.

Nursing Assessment

  • Auscultate apical pulse for a full 60 seconds before each dose.
  • In adults, hold and notify provider when apical heart rate is below 60 bpm unless alternate ordered parameters exist.
  • Hold dose and notify provider for infant apical heart rate under 100 bpm unless alternative ordered threshold exists.
  • Follow ordered age-specific heart-rate hold parameters for older children.
  • Monitor ECG/rhythm trends for bradycardia, conduction delay, or new dysrhythmias.
  • Screen adult contraindication patterns before dosing, including acute myocardial infarction context, ventricular fibrillation, and Wolff-Parkinson-White pathways.
  • Assess for toxicity cues: nausea, vomiting, visual changes (for example halos), poor feeding, bradycardia, rhythm instability, and perfusion decline.
  • Recognize increased toxicity risk with decreased renal function, hypokalemia, hypercalcemia, hypomagnesemia, and advanced age.
  • Monitor potassium and magnesium trends closely; depletion lowers toxicity threshold.
  • Reconcile concurrent medications, especially diuretics and other rate/rhythm agents.

Nursing Interventions

  • Perform independent dose verification with weight-based calculation before administration.
  • Administer digoxin separately (not mixed with formula or breast milk) to avoid incomplete dosing.
  • Coordinate serum-level timing and electrolyte monitoring per pediatric protocol.
  • Escalate suspected toxicity immediately and prepare for urgent rhythm/perfusion support.
  • Anticipate digoxin immune fab for life-threatening toxicity and monitor closely after administration for worsening heart failure, worsening atrial fibrillation, and hypokalemia.
  • Reinforce caregiver teaching on schedule consistency and missed-dose handling; if a child vomits after a dose, do not redose and give the next scheduled dose unless provider gives different instructions.
  • Reinforce immediate reporting of poor feeding, repeated vomiting, lethargy, bradycardia, or breathing changes.
  • Document pre-dose apical heart rate, administered/held decision, and clinical response after dosing.

Narrow Therapeutic Index

Digoxin toxicity can progress quickly in infants and children; early signs must be treated as high-acuity findings.

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