AED Defibrillators

What are AED Defibrillators?

AED (automatic external defibrillator) type defibrillators are the type typically found in public environments for public use or they may be privately owned or rented by a business or organisation to provide a vital life saving solution in the case of immediately life threatening cardiac arrest (the heart has stopped) events.

AED Defibrillator

AED’s are small, lightweight, therefore portable electrical devices (self contained battery on board). As part of an emergency plan, an AED should be mobilised in the event that someone has collapsed or is in danger of doing so (due to accident or sudden onset of illness, for example a heart attack). Although mobilised the AED should only be turned on and used if a casualty is, or becomes unconscious (unresponsive) and stops breathing normally.

When the AED is turned on it will give loud and clear verbal instructions to provide a potentially untrained rescuer step by step guidance in the use of the equipment. All AED’s work with this voice prompt system – they ask the rescuer(s) to call 999 and ask for the ambulance service.

How Do AED Defibrillators work?

The AED has two sticky electrode pads that will be attached to the casualty’s body. Once the pads are on the casualty’s body the AED will analyse the electrical activity in the casualty’s heart. Should the AED detect a catastrophic (immediately life threatening) electrical arrhythmia (abnormal electrical activity known as ‘VF’ – ventricular fibrillation) it will either instruct the rescuer(s) to press the shock button to deliver a defibrillation shock (a significant and specific type of electrical energy) to the casualty’s heart or it will deliver the shock automatically after giving a clear warning that it is about to do so.

The endeavour here is for the defibrillation shock to momentarily stop all the electrical activity in the heart for just a few moments (2 – 3 seconds). Then the hope is that the heart’s on board pace maker ‘fires’ and initiates a normal sequence of electrical impulses that are required for the heart to operate normally, thus saving the casualty’s life. Defibrillators are incredibly reliable at doing just this.

If there is no immediate response from the defibrillation shock the AED will also instruct the rescuer(s) to provide CPR (resuscitation) as part of the emergency response. Most AED’s will provide a metronome bleep to help pace the compressions during CPR and some machines coach the rescuer in order to optimise the CPR process.

It is important to know that while no previous training in the use of AED equipment is required to use one in an emergency, outcomes of rescues where rescuers have had formal competency training are likely to be more favourable – quite simply the difference between a life saved or a life lost.

AED Defibrillator Training

At First Aid Training Now we are able to provide appropriate competency training in the use of AED equipment. Please see our course ‘Responding to incidents with an AED’ on ‘First Aid Courses’ page.

Please note that we deliver full AED competency training on our 3 day First Aid at Work course and AED awareness training on our 1 day Emergency First Aid at Work course.

Defibrillator training

For further information on AED defibrillators and if you wish to rent or buy an AED, please visit our sister organisation


0800 112 3885


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