Defibrillation

In defibrillation—conversely to electrical cardioversion—shocks are not synchronized with the electrocardiographic (ECG) R wave. External defibrillation is performed by delivering a shock from the defibrillator through the chest wall. Automated defibrillation is performed using an automated external defibrillator (AED), which is capable of analyzing the heart rhythm and indicating whether a shock is necessary.

IndicationsTop

Cardiac arrest caused by ventricular fibrillation (VF); pulseless ventricular tachycardia (VT) including the fastest form: ventricular flutter (monomorphic VT at a rate up to 300 beats/min).

ContraindicationsTop

None, assuming the use of defibrillation is not excluded based on the patient’s previously expressed wishes.

ComplicationsTop

Asystole, skin burn at the electrode application sites.

EquipmentTop

Defibrillator, adhesive electrode pads or manually applied defibrillator paddles, conductive gel, disposable gloves.

Defibrillators are classified based on delivered electrical shock as:

1) Monophasic: Delivered current travels in one direction between the electrodes.

2) Biphasic: Delivered current travels in both directions between the electrodes.

Monophasic defibrillators require a higher energy discharge, are less effective, and are no longer manufactured, but older models may still be in use in some centers. All AEDs are biphasic.

ProcedureTop

1. Manual defibrillator: see Cardiac Arrest.

2. AED: see Cardiac Arrest.