- Preparing the defibrillator

The first step in preparing the defibrillator is to ensure that it is set to deliver a synchronised shock. An unsynchronised shock could coincide with a T wave and cause ventricular fibrillation (VF). By avoiding the relative refractory period, the risk of inducing VF is minimised.

You should ensure that you give a shock of the correct energy to your patient, preferably a biphasic shock unless only monophasic equipment is available:

For a broad-complex tachycardia or atrial fibrillation, start with a 120 - 150 J biphasic shock (200 J monophasic) and increase in increments if this fails.

Atrial flutter and regular narrow-complex tachycardia will often be terminated by lower-energy shocks: start with 70 - 120 J biphasic (100 J monophasic).

For patients who are in atrial fibrillation or atrial flutter, use anteroposterior self-adhesive pad positions when it is practicable to do so.

When delivering the shock, press the shock button and keep it pressed until after the shock has occurred – there may be a slight delay before the shock is delivered. If further shocks are needed, reactivate the synchronisation switch before each shock if necessary.