Digoxin toxicity: Difference between revisions
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*[[Digoxin Immune Fab]] | *[[Digoxin Immune Fab]] | ||
*[[Toxidromes]] | *[[Toxidromes]] | ||
*[[Digoxin]] | |||
== Source == | == Source == |
Revision as of 21:52, 18 November 2011
Background
- Positive inotropic effect
- Inhibits Na-K pump -> incr extracelluar K, incr intracellular Na -> incr intracellular Ca
- Increases vagal tone
- Can lead to bradyarrhythmias (esp in young)
- Increases automaticity
- Can lead to tachyarrhythmias (esp in elderly)
- Renally cleared
- Hemodialysis does not work
- 1 fab vial binds 0.5mg of digoxin
Risk Factors
- Electrolyte Imbalance
- Hypokalemia, hypomagnesemia, Hypercalcemia
- Hypovolemia
- Renal insufficiency
- Cardiac ischemia
- Hypothyroidism
- Meds
- CCBs, amiodarone
Clinical Manifestations
Cardiac
- Any type of dysrhythmia is possible except for rapidly conducted atrial arrhythmias
- Most common:
- PVCs
- Bradycardia
- Digitalis Effect
- T wave changes
- QT interval shortening
- Scooped ST segments with depression in lateral leads
GI
- Nausea/vomiting
- Abdominal pain
Neuro
- Confusion
- Weakness
- Visual disturbances
- Yellow halos
- Scotomas
- Delirium
Work-Up
- Dig level
- Normal = 0.8-2 ng/mL (ideal = 0.7-1.1)
- May have toxicity even with "therapeutic" levels
- Measure serum level at least 6 hours after acute ingestion (if stable), immediately for chronic ingestion
- If measure before this may be falsely elevated due to incomplete drug distribution
- Normal = 0.8-2 ng/mL (ideal = 0.7-1.1)
- Chemistry
- Hyperkalemia level correlates with degree of toxicity
- Hypokalemia increases susceptibility in chronic toxicity
- Hypomagnesemia is common
- Cr/BUN
- Urine output
- ECG (serial)
Treatment
- Digoxin Immune Fab
- Activated Charcoal
- Questionable efficacy
- Only an adjunctive tx; NOT an alternative to fab fragment therapy
- Consider only if present within 1 hr of ingestion
- 1g/kg (max 50g)
Rhythm Disturbances
- Fab fragments is the agent of choice for all dysrhythmias!
- Bradyarrhythmias (symptomatic)
- Atropine 0.5mg IV
- Pacing
- Tachyarrhythmias
- Lidocaine
- 1-3mg/kg over several minutes, followed by 1-4mg/min
- Phenytoin
- May enhance AV conduction
- Infuse at 25-50 mg/min to a loading dose of 10-15mg/kg
- Lidocaine
- Cardioversion
- Consider lower energy settings (25-50J)
Hyperkalemia
- Treat with Fab, not with usual meds
- Once fab is given hyperkalemia will rapidly correct
- Aggressive tx with potassium-lowering agents could cause sig hypokalemia following therapy
- If Fab is not available and hyperkalemia is life-threatening then treat
- Calcium is controversial (some say dangerous, others say not)
Hypokalemia
- Chronic intoxication
- Raise level to 3.5-4
- Acute intoxication
- Do not treat (likely that potassium level is rapidly rising)
Hypomagnesemia
- Treat with 1-2g over 10-20 min
- Monitor for resp depresion
- Avoid in pts with:
- Renal failure
- Bradydysrhythmias/conduction blocks
See Also
Source
Rosen's