How Does an Automated External Defibrillator (AED) Work?

There are several cases where one’s heart collapses and goes into sudden cardiac arrest. In this case, emergency medical devices such as the defibrillator are required to save the person.

So the question is, how does an automated external defibrillator work? This blog will discuss the automated external defibrillator (AED) and how it works.

What is a defibrillator?

Defibrillators are devices that send an electric pulse or shock to the heart to restore a normal heartbeat. They prevent or correct an uneven heartbeat.

If the heart suddenly stops, defibrillators can help it beat again. An automated external defibrillator (AED) is a lightweight, portable device that delivers an electric shock through the chest to the heart.

How exactly does an AED work?

AED generates a relatively high electrical current (up to 360 joules for some models of AEDs) and then passes it through to the heart. In this way, the heartbeat comes back to normal immediately.

The device doesn’t ‘restart the heart’ literally. Instead, it resets the heart's natural pacemaker (which makes it beat with a regular rhythm), thus restoring the normal functioning of the heart.

How to use the AED?

Though AEDs feature automated functionality, and many are installed in public locations and even guide the user through the process, it’s still important to know how to use them to treat victims as quickly as possible.

If you have a helper, ask them to continue CPR while you get the AED ready. If they are untrained, ask them to give chest compressions only. And follow these steps:

  • Switch on the AED immediately and follow the voice prompts.
  • Attach the leads to the AED if necessary and attach the pads to the victim's bare chest (do this while your help performs CPR).
  • You may need to towel dry or shove the chest so the pods stick correctly. Only shave excessive hair and don't delay defibrillation; a razor is not immediately available.
  • Peel the backing from one pod at a time and place it firmly in position, following the instructions in the pods.
  • Place one pad below the casualty's right collarbone.
  • Place the other pad around the casualty's left side, over the lower ribs.
  • DO NOT remove the pads if you have placed them the wrong way around, and the AED will still work.
  • While the AED analyses the rhythm-stop CPR and ensures no one touches the casualty.
  • If a shock is indicated, deliver the shock.
  • Make sure that nobody is touching the casualty.
  • Push the shock button as directed (fully automatic AEDs will deliver the shock automatically).
  • Immediately restart CPR at a ratio of 30:2.
  • Continue as directed by the voice/visual prompts.
  • If a shock is not indicated, continue CPR.
  • Immediately restart CPR at a ratio of 30:2.
  • Continue as directed by the voice/visual prompts.

How to use an AED on children and babies?

Most AEDs can connect ‘Paediatric’ pads or have a paediatric setting to reduce shock size. And this is best for babies or children under 8 years. If you only have adult pads, you should use them (this is better than not using an AED at all).

Where can I get AED training?

The Mandatory Training Group UK offers CPR and AED online training courses. You may also visit

Where can I find online automated external defibrillator (AED) training courses, qualifications and programmes?

The Mandatory Training Group is the leading UK provider of accredited online automated external defibrillator (AED) training courses for all sectors, including health and social care, education, local government, private companies, charitable and third sector organisations.

Alternatively, you can contact our helpful Support Team byclicking hereto tell us your more about online automated external defibrillator (AED) training courses.

Online training courses and qualifications about automated external defibrillator (AED)

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How does an Automated External Defibrillator (AED) Work? - The Mandatory Training Group UK.

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