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
- Acute poisoning:
- Supportive- Intubation, fluid status, etc
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/
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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