Digoxin toxicity Flashcards
therapeutic range for digoxin
0.8-2.0 ng/ml and cleared by kidneys
what can lead to digoxin toxicity
recent illnesses (gastrointeritis) can lead to volume depletion, AKI which can cause digoxin to NOT clear. Can have hypokalemia, hypomagnesemia, hyperCal and myocardial ischemia
Presentation of acute digoxin toxcity
lethargy, fatigue, delirium, confusion, disorientation, weakness, visual changes in color scotomas, blindness)
Cardiac arrhythmias from digoxin
parosymal atrial tachycardia,
AV block, PVCs,
regularized a fib (regular R to R interval) ,
bidirectional VT (QRS complexes from 2 ectopic foci) or V fib.
bradycardia (due to markedly enhanced vagal effect)
acute digoxin toxicity with GI symptoms:
anorexia, nausea, vomiting, abdominal pain.
Chronic digoxin toxicity
less GI symptoms and more neurological and visual symptoms (changes in vision color, scotomas or blindness
what are scotomas
areas in visual field which are blind
what makes digoxin toxicity so dangerous
the cardiac arrhythmias
does serum digoxin levels correlate well with digoxin toxicity?
no they don’t. DIgoxin toxicity can occur within “normal” or subtherapeutic levels.
Need to diagnose digoxin toxicity based on clinical presentation and EKG findings
initial treatment of digoxin toxicity:
IVFs,
then give digoxin specific antibody (Fab) fragments for anyone with:
life threatening cardiac arrhythmia (AV block with junctional rhythm as this pt)
end organ dysfunction due to hypoperfusion
hyperkalemia (serum K >5.5 mEq)
treat hypokalemia if present
no medications that can increase K (succinylcholine in rapid sequence intubation)
does dialysis help with clearing/treating digoxin toxicity?
no. it doesn’t help because high molecular weight and large volume of distribution for drug
but can be an option if digoxin specific antibodies fail
what electrolyte abnormalities are associated with digoxin toxicity?
elevated K >5.5
drug stops Na/K ATPase pumping of potassium into cells.
how does digoxin cause hyperkalemia?
it causes excessive inhibition of sodium potassium ATPase in cardiac myocytes leading to hyperkalemia.
High K is a predictor of mortality and severity in acute digoxin toxicity so instead of treating high K aim to decrease digoxin
Do we ever give IV amiodarone to treat digoxin induced atrial or ventricular tachyarrhtymias?
no and contraindicated in acute digoxin toxicities because it competes with digoxin for renal excretion and can increase serum digoxin levels
EKG changes with digoxin toxicity?
See shortened QT intervals and scooped ST segments and T wave abnormalities.
most frequent rhythms are sinus arrest, atrial tachycardia, junctional tachycardia, AV block, PVCs and VT.
virtually any rhythm can be seen.
