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Using an AED (Automated External Defibrillator)

The UK has seen a huge increase in the prevalence of AEDs, both in the workplace and within communities. In the UK, less than one in 10 people survive a cardiac arrest, and for every minute without defibrillation, a person’s chance of survival decreases by around 10 percent.

How to Use an AED

1. Switch on the AED

  • As soon as you arrive at the casualty’s side with the AED, turn it on, whilst CPR is continued.
  • Remove or cut through clothing and wipe away sweat from the chest if necessary
2. Stick on the Pads
  • Attach the pads to the casualty's chest in the positions indicated on the pads

3. Follow the Instructions

  • Follow the voice and/or visual prompts given by the machine.
  • AED

Continue until: emergency help arrives; the casualty shows signs of becoming responsive – such as coughing, opening eyes, speaking or moving purposefully – and starts breathing normally; or you are too exhausted to continue.

Do not leave the casualty to search for an AED. Instead, call for help and ask for the nearest AED. If no one is available you should call 999/112 from your mobile phone and turn on your loudspeaker and commence CPR. The general principles remain the same for any AED.


The use of an AED can only improve chances of survival – you cannot accidentally administer a shock to a patient who does not require it, as the AED itself will assess the heart rhythm and will only charge if it detects a shockable rhythm.

You can purchase an AED along with other first aid supplies from our St John Cymru supply website.

If your workplace has an AED and you would like training or if you'd like to learn how to use one yourself, find out more about our AED training here.

The Welsh Government encourages all organisations and communities to register their AEDs via the Welsh Ambulance Service – this can be accessed via this link click here.

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St John Cymru Wales
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