S15C187 - Digoxin toxicity

Question 1

Digoxin Pharmacology

Answer 1

• increases intracellular Na, by blocking Na/K ATPase pump leading to increase in intracellular calsium resulting in increased inotropy
• allso decreases AV node conduction and therefore can treat SVT but leads to bradycardia
• normal dose: 125-250mcg
• toxic dose: 1-2mg (fatalities seen at 10mg adults 4mg children)

Question 2

Digoxin toxicity: clinical picture

Answer 2

• syncope, dysrhythmia
• GI Sx, dizzy, h/a, weak, Sz
• confusion, disorientation, delirium, hallucinations
• see yellow-green halos around objects

Question 3

Dig Tox DDx

Answer 3

-other toxins that cause bradyarrhythmias:
CCB
BB
class IA antiarrhythmics (procainamide, quinidine)
Clonidine
Organophosphate poisonoinng
Plants: rhododendron, monkshood, tobacco, false hellebore, yew berry
SSS

Question 4

ECG findings of a pt on digoxin (therapeutic)

Answer 4

• T wave flattening or inversion
• QT shortening
• Scooped ST segment with ST depression
• increased U wave amplitude

Question 5

Dig Toxicity and K

Answer 5

• hyperkalemia occurs d/t inhibition of Na/K ATPase pump in acute ingestions
• K may be normal in a chronic toxicity

Question 6

Dig levels

Answer 6

• do not rely on level for toxicity, clinical picture more important
• therapeutic levels: 0.5-2 nanograms/ml

Question 7

Dig Tox: Tx

Answer 7

-asymptomatic: cardiac monitor, charcoal, have digi-fab ready if needed
-symptomatic:
ABC (monitor)
D: charcoal
F: digiFab
bradyarrhythmia: atropine 0.5-2mg IV, PM
ventricular dysrhythmia: MgSO4- 2-4g IV, lidocaine, phenytoin, DC CV
arrest: ACLS
hyperkalemia: AVOID CALCIUM (stone heart), glucose-insulin, sodium bicarb, digiFab, kayexalate, HD
hypomagnesemia: MgSO4

• if given digiFab, send to ICU
• if asymptomatic monitor for 12h