Digitalis Overdose

First Things First (assess & treat for the following)

  • Treat life-threatening conditions
  • Begin with ABCs
    • Correct hypoxia, hypoglycemia, hypovolemia, and electrolyte abnormalities
    • Dysrhythmias
      • Bradydysrhythmias
        • Atropine
        • Cardiac pacing
        • Fab fragments
      • Ventricular dysrhythmias
        • Fosphenytoin or lidocaine
        • IV magnesium
        • Fab fragments
        • Cardioversion—last resort
    • Hyperkalemia
      • Glucose, insulin, sodium bicarbonate, enteral potassium binding resin
      • Fab fragments
  • GI decontamination
    • Activated charcoal
  • Pharmacology
    • Digoxin is the most common preparation of digitalis.
    • Found in foxglove, oleander, lily of the valley
    • Inhibits Na+- K+- ATPase pump
      • Normally this pump concentrates Na+ extracellularly and K+ intracellularly.
      • Provides the Na+ gradient that powers the Na+- Ca++ antiporter, which extrudes Ca++ from the cell
    • May also increase cytosolic Ca++ by interactions with the L-type calcium channels and interactions with the Ca++ triggered calcium release from the myocardial sarcoplasmic reticulum
    • Effects of increased Ca++ inside the cell are:
      • Increased inotropy
      • Increased automaticity
      • Shortening of atrial and ventricular repolarization
      • Decreased rate of conduction through the sinoatrial and atrioventricular nodes both directly and through increased vagal tone
      • Excessive increase in Ca++ by excessive digoxin results in transient late depolarizations that may initiate contractions.
  • EKG
    • Decrease in ventricular response rate for SVT
    • QT segment shortening
    • ST segment and T-wave forces opposite in direction to the major QRS forces

There's more to see -- the rest of this topic is available only to subscribers.

Last updated: April 26, 2010