Resuscitation with an AED (Automated External Defibrillator)

Automated External Defibrillation

Appendix Resuscitation with an AED

The most common cause for a heart to stop (cardiac arrest) is a ‘heart attack’.
It is worth noting that a heart attack does not always cause a cardiac arrest and the majority of people who suffer a heart attack stay conscious and survive. 

If a heart attack (or other cause) results in a cardiac arrest, it is usually because it has interrupted the heart’s electrical impulses. When this happens the heart quivers chaotically instead of beating in a co-ordinated rhythm. This is called ‘Ventricular Fibrillation’ (VF).

The definitive treatment of Ventricular Fibrillation is to deliver a controlled electric shock through the heart, to stop the ‘quivering’ and enable it to beat normally again. This is called ‘defibrillation’. 

An Automated External Defibrillator (AED) is a safe, reliable, computerized device that can analyze heart rhythms and enable a non-medically qualified rescuer to safely deliver the life saving shock with a small amount of training. 

The use of an AED can dramatically increase the chances of survival if a patient’s heart stops beating, but it must be used promptly – for every one minute delay in delivering the shock, the patient’s chance of survival reduces by up to 10%.

Your fast action and decision making helps increase the chance of survival for a casualty.

Resuscitation with an AED


  • Check that it is safe for you to help the casualty. Do not put yourself at risk.
  • Consider the safety implications of using an AED in this situation.

Appendix Resuscitation with an AED 2


• Gently shake the shoulders and ask loudly ‘Are you alright?’

If there is no response:

  • Shout for help immediately.
  • If possible, ask one helper to dial 999 and another to get the AED, but do not leave the casualty yourself just yet.


  • Carefully open the airway by using ‘head tilt’ and ‘chin lift’.
  • Look inside the mouth to see if there are any obvious obstructions.

Appendix Resuscitation with an AED 3


  • Keeping the airway open, look, listen and feel to see if the breathing is normal. Take no more than 10 seconds to do this.
  • If the casualty is breathing normally, consider possible injuries and carefully place them in the recovery position.

Appendix Resuscitation with an AED 4

If the casualty is not breathing normally

  • If you are on your own, dial 999 for an ambulance and get the AED – you may need to leave the casualty to do this.
    If you have help – start CPR immediately whilst your helper(s) get the AED and dial 999.
  • Continue CPR until the AED arrives.

When the AED arrives

  • If you have a helper, ask them to continue CPR whilst you get the AED ready.

Appendix Resuscitation with an AED 5

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 whilst your helper performs CPR if possible).
  • You may need to towel dry or shave the chest so the pads adhere properly. Only shave excessive hair and don’t delay defibrillation
    if a razor is not immediately available.
  • Peel the backing from one pad at a time and place firmly in position, following the instructions on the pads.

Appendix Resuscitation with an AED 8

  • Place one pad below the victim’s right collar bone.
  • Place the other pad on the victim’s left side, over the lower ribs. Place this pad vertically if possible (see below).

Appendix Resuscitation with an AED 9

  • DO NOT remove the pads if you have placed them the wrong way around – the AED will still work.
  • Whilst the AED analyses the rhythm – stop CPR and
    ensure that no one touches the casualty.

If a shock is advised

  • Ensure that nobody touches the casualty (check from top to toe and shout ‘stand clear!’)

Appendix Resuscitation with an AED 6

  • Push the shock button as directed (fully-automatic AEDs will deliver the shock automatically).
  • Continue as directed by the voice / visual prompts.

Appendix Resuscitation with an AED 7

If a shock is NOT advised

  • Immediately resume CPR using a ratio of 30 chest compressions to 2 rescue breaths.
  • Continue as directed by the voice and visual prompts.

Placement of the pads

Wet chest

  • If the patient’s chest is wet (perfuse sweating for example), it must be dried before applying the pads so they adhere to the chest properly.
  • Also dry the chest between the pads so electricity does not ‘arc’ across the wet chest.

Appendix Resuscitation with an AED 13

Excessive chest hair

  • Chest hair will prevent the pads adhering to the skin and will interfere with electrical contact. Only shave the chest if the hair is excessive and even then spend as little time as possible on this.
  • Do not delay defibrillation if a razor is not immediately available.

Appendix Resuscitation with an AED 14

Pad positioning

Recent studies have found that the position of the pad on the lower left chest can affect the effectiveness of the shock.

Ensure the pad is placed around the side of the chest (not on the front) and place it vertically (see picture). This ensures the maximum electricity flows through the heart rather than across the chest surface.

Until manufacturers update them, some AED pads will have diagrams showing horizontal placement – ignore this and place the pad vertically.

Appendix Resuscitation with an AED 10Appendix Resuscitation with an AED 11

Appendix Resuscitation with an AED 12

AED safety considerations

Electrical shock

Recent tests have shown that if the patient’s chest is dry ijrtd the pads are stuck to the chest correctly, the risk of electrical shock is very low, because the electricity only wants to travel from one pad to the other, not to ‘earth’ like mains electricity. To be extra safe however, briefly check that nobody is touching .the patient before delivering a shock.

DO NOT delay delibrillation because the patient is on a wet or metal surface – providing the chest is dry it is safe to deliver the shock.

Medication patches

Some patients wear a patch to deliver medication (such as a nicotine patch). Some heart patients wear a ‘glyceryl tri-nitrate’ (GTN) patch. This type of patch can explode if electricity is passed through it, so remove any visible medication patches as a precaution before delivering the shock.

Appendix Resuscitation with an AED 15

Highly flammable atmosphere

There is a danger of the AED creating a spark when the shock is delivered, so it should not be used in a highly flammable atmosphere (in the presence of petrol fumes for example).


Take care not to place the pads over jewellery such as a necklace. This would conduct the electricity and burn the patient. There is no need to remove pierced jewellery, but try to avoid placing the pads over it.

Appendix Resuscitation with an AED 16

Implanted devices

Certain heart patients may have a pacemaker or defibrillator implanted. You can often see or feel them under the skin when the chest is exposed and there may be a scar. They are usually implanted just below the left collar bone, which is not in the way of the AED pads, but if a device has been implanted elsewhere, try to avoid placing the pad directly over it.

Appendix Resuscitation with an AED 17

Inappropriate shock

AEDs are proven to analyse heart rhythms extremely accurately, however, the patient needs to be motionless whilst the AED does this. Do not use an AED on a patient who is fitting (violent jerking movements) and ensure vehicle engines or vibrating machinery are switched off whenever possible.

AED use on children

Normal ‘adult’ AED pads are suitable for a child older than 8 years. Smaller pads that reduce the current delivered are available for children aged 1 to 8. These should be used for that age range where available. Some AEDs have a ‘pediatric’ setting. 

If the child is older than 1 year and you only have adult pads, use the AED as it is. The use of adult pads on a child under 1 year is not recommended.

Appendix Resuscitation with an AED 18

Book Your First Aid Training

These lessons and information do not replace actual attendance on a first aid course, getting hands on practice with your first aid skills is the best way to ensure you are a competant and capable first aider.

If you would like to book a first aid course or if you have a question for us please call 0191 7166601, email or complete our online enquiry form and a member of the team will get back to you shortly.

We provide workplace onsite training for Emergency First Aid, First Aid at Work and Paediatric First Aid but a range of other First Aid Courses across the North East, our first aid training centre is based in South Shields

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