defibrillation (electrical cardioversion, automated external difibrillation, AED)

Indications

• termination of life-threatening ventricular arrhythmias
  • ventricular tachycardia (VT)
  • ventricular fibrillation/flutter (VF)
• termination of supraventricular tachyarrhythmias
  • hemodynamic compromise
  • atrial fibrillation/atrial flutter refractory to carotid sinus massage or chemical cardioversion
  • if atrial fibrillation/atrial flutter is known to be of < 48 hours in duration, attempt synchronized cardioversion
  • patients without hemodynamic compromise for which atrial fibrillation or atrial flutter may be of > 48 hours in duration should be anticoagulated for 3 weeks prior to cardioversion
    • anticoagulation should be continued for 3 weeks after cardioversion
  • synchronized cardioversion
    • begin 50 joules
    • then 100, 200, 300, 360 joules

Contraindications

• atrial fibrillation with digitalis toxicity toxicity should be alleviated before cardioversion/ defibrillation

Benefit/risk

• number needed to treat (NNT)
  • rapid defibrillation after cardiac arrest
    • 2.5 to prevent 1 death
    • no identified harm

Procedure

Protocol: automated external defibrillator

Also see protocol for manual defibrillators

• turn on defibrillator
• attach to victim
  • select correct pad size for victim's size & age
  • open package, expose adhesive surface & attach to victim upper right sternal border & cardiac apex
  • attach directly to chest wall, do NOT defibrillate through clothing
  • attach cables if needed
• analysis, place in analysis mode
  • announce 'Analyzing rhythm - stand clear'
  • verify
    • no victim movement
    • no one in contact with victim
  • analyze, press analyze (some AEDs omit this control)
• shock
  • if VF/VT is present, AED will charge to 150-360J
  • announce 'shock is indicated - stand clear'
  • verify no one is touching victim
  • apply 25 lbs of pressure on both paddles
  • press 'shock' button'
• resume CPR after shock
  • continue CPR for 2 minutes prior to analyzing rhythm
  • cycles of 2 minutes of CPR, analyze rhythm, shock if rhythm is shockable
  • repeat cycle of 2 minutes after shock until VF/VT no longer present

Notes

Other considerations:

• unconscious adults with return of spontaneous circulation after out-of-hospital cardiac arrest be cooled to 32 to 34 Celsius for 12 to 24 hours when the initial rhythm was ventricular fibrillation

More general terms

• cardioversion

Additional terms

• 'quick-look' paddle
• protocol for manual defibrillators