Thanks to Dr. Kopping for presenting today’s Morning Report!

 

Digoxin Toxicity

  • Digoxin falls under cardioactive steroids
    • Fox glove, oleander, dried toad secretions
  • Na/K ATPase inhibition
    • Resting potential more positive, more likely to depolarize
    • Increases inotropy by preventing Ca leaving cell via Na/Ca channel
    • Increases automaticity
  • Narrow therapeutic window
    • Poisoning carries with it high morbidity/mortality when left untreated
  • Symptoms
    • GI (N/V/D), fatigue, vision changes, yellowing of vision, confusion, delirium, hallucinations, bradycardia, occasionally tachycardia
  • Prior to advent of treatment, if K level is
    • <5 0% mortality
    • 5-5.5 50% mortality
    • >5.5 100% mortaility
    • Hypokalemia potentiates toxicity
  • EKG findings
    • Just about anything accept for a supraventricular tachycardia with 1:1 conduction given AV nodal block
    • Specific- Bidirectional ventricular tachycardia (more than 1 ectopic foci)
    • Specific- accelerated junctional tachy
  • Treatment
    • Supportive- Intubation, fluid status, etc
      • Potential for GI decontamination/gastric lavage/activated charcoal in acute ingestions
    • Hyper K
      • Stay away from calcium salts
      • Other typical treatments
    • Hypo K
      • Replete immediately, will only potentiate toxicity if not
    • Digibind/fab
      • Binds to intravascular digoxin which is then cleared via kidneys
      • Complex able to be removed using HD, although slow
      • Because volume of distribution is large, goes into tissues
        • Start removing complex, dig from tissues goes into intravascular space- “rebound toxicity”
      • How much?
        • Acute poisoning:
          • number of vials = Ingested dose (mg) x 0.8 (bioavailability) x 2 (note that 0.8 represents the 80% oral bioavailability of digoxin)
          • Unknown dose start with 5 vials if HD stable, 10 if HD unstable, 20 if in cardiac arrest. Re-dose every 30 minutes if still symptomatic
        • Chronic poisoning:
          • (serum digoxin concentration – ng/L) x (weight – kg) ÷ 100, round up
          • Many labs will give nM/L à divide by 1.28
          • Unknown level, start with 2 vials, re-dose in 30 minutes as needed
        • Initial response in 20-30 minutes, max at 90

 

References:

http://www.docstoc.com/docs/83478943/Digoxin-Toxicity-%28PowerPoint%29

http://www.nlm.nih.gov/medlineplus/ency/article/000165.htm

http://lifeinthefastlane.com/ccc/digoxin-toxicity/

 

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Jay Khadpe MD

  • Editor in Chief of "The Original Kings of County"
  • Assistant Professor of Emergency Medicine
  • Assistant Residency Director
  • SUNY Downstate / Kings County Hospital

Latest posts by Jay Khadpe MD (see all)


Jay Khadpe MD

  • Editor in Chief of “The Original Kings of County”
  • Assistant Professor of Emergency Medicine
  • Assistant Residency Director
  • SUNY Downstate / Kings County Hospital

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