USMLE Prep - Medical Reference Library

Digoxin Toxicity — Digoxin Immune Fab

System: Cardiology • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Bradyarrhythmias, gastrointestinal symptoms, and hyperkalemia suggest toxicity; treat unstable rhythms, give digoxin immune Fab for standard indications, and correct electrolytes.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

For Digoxin Toxicity Digifab, frame the differential by acuity and pathophysiology, then align diagnostics to the leading hypotheses. Prioritize stabilization while obtaining high‑yield studies such as EKG (Rhythm/ischemia), Troponin (Myocardial injury), CXR (Pulmonary edema/size), BMP/Mg2+ (Electrolytes/renal). Incorporate bedside imaging and targeted labs to define severity and identify complications; synthesize results with clinical trajectory to refine the working diagnosis and disposition needs.


Treatment Strategy & Disposition

Initiate disease‑directed therapy alongside supportive care, titrating to objective response. Pharmacologic options commonly include Aspirin, P2Y12 inhibitor, Heparin/LMWH, Beta-blocker. Use validated frameworks (e.g., When to Give Fab (Abbrev.)) to guide escalation and site of care. Address precipitating factors, de‑escalate empiric therapies with data, and arrange follow‑up for monitoring and risk‑factor modification; admit patients with instability, high risk of deterioration, or needs for close monitoring.


Epidemiology / Risk Factors

  • Atherosclerotic risk (HTN, DM, HLD, smoking)
  • Age/family history of premature CAD

Investigations

TestRole / RationaleTypical FindingsNotes
EKGRhythm/ischemiaST-T changes/arrhythmiaSerial
TroponinMyocardial injuryDynamic rise/fallTrend
CXRPulmonary edema/sizeCardiomegaly/edema
BMP/Mg2+Electrolytes/renalDerangements
CBC/CoagsBleeding riskAbnormal/INR

When to Give Fab (Abbrev.)

ScenarioRationale
Life threatening arrhythmiaHigh mortality risk
Severe hyperkalemia with toxicityMarker of severe poisoning
Massive ingestion with level elevationPreempt severe toxicity

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Digoxin immune FabAntibody fragmentMinutesUnstable arrhythmia/hyperkalemiaAllergy; rebound HF
Potassium correctionElectrolyteHoursAvoid hypokalemiaArrhythmia

Prognosis / Complications

  • Prognosis by ischemic burden/LV function
  • Arrhythmias and HF are complications

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

Notes

Fab dosing can be calculated from ingested dose or level; consult poison center for complex cases.


References

  1. ACMT Digoxin Toxicity Guidance — Link
  2. AHA Arrhythmia Statements — Link