DIGOXIN: The drug, the myth, the poisoning
* 60% renal eliminated; RENAL FAILURE makes it stick around longer (6 days!)
* Cellular effect = INCREASED potassium OUTSIDE the cell
* Systemic effect = INCREASED inotropy, slowed AV nodal conduction
* When do I suspect it?? Because chronic toxicity may have a normal digoxin level...
= Lethal combination of hyperkalemia, dysrhythmia and cardiac arrest
- In cases where the digoxin level is normal:
* increased automaticity/irritability (PACs, PVCs) gives you a 70% chance of dig toxicity;
* increased automaticity with ANY OTHER FEATURE (bradycardia, GI symptoms...) give you >80% likelihood of dig toxicity
* For more about normal dig levels with toxicity: https://www.ncbi.nlm.nih.gov/pubmed/23685098
* Treatment:
Prevent cardiac arrest. Period.
DIGIBIND is DEFINITIVE
Symptomatic control:
* Bradyarrhythmias:
- Atropine and adrenaline (but may increase cardiac irritability)
- Pacing: usually doesn't work
* Tachyarrhythmias:
- Consider MAGNESIUM
- Cardioversion: usually doesn't work
* Hyperkalemia:
- Calcium: To give or not to give, that is the question. (This is its own POD. For now, read this: https://lifeinthefastlane.com/ccc/calcium-digoxin-toxicity-and-stone-heart-theory/)
- Insulin, glucose, bicarbonate
But again: DIGIBIND, DIGIBIND, DIGIBIND
* Take this in the clinical context that one vial of digibind = $700
* Hard indications = digoxin at home plus:
cardiac arrest
life-threatening dysrhythmia
K>5
bad GI s/s
any of the above + new renal failure
* ACUTE: # vials needed = dose (mg) x 1.6 OR:
stable = 5 vials
unstable = 10 vials then repeat doses of 5 vial q30mins until improved EKG
cardiac arrest 2/2 digoxin toxicity = 20 vials (if you have that much!)
* CHRONIC: # vials needed = dig level (ng/L) x wt (kg) / 100 OR: if unk dose = 2 ampules, observe for clinical response