Morning Report: 7/7/2015

by Jay Khadpe MD • July 7, 2015 • Comments Off

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/

The views expressed on this blog are the author's own and do not reflect the views of their employer. Please read our full disclaimer here. Any references to clinical cases refer to patients treated at a virtual hospital, Janus General Hospital.

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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