To use an automated external defibrillator (AED), you need to switch it on and follow its voice prompts. Bare the person's chest and stick the pads where the pictures show, with one below the right collarbone and the other on the left side below the armpit. Keep everyone clear while the AED analyses the heart rhythm, press the shock button only if it tells you to, and then restart CPR straight away.
What does an AED do?
An AED reads the heart's electrical rhythm through two sticky pads and decides whether a shock could help. It should only be used on someone who is unresponsive and not breathing normally.
The AED looks for a shockable rhythm, such as ventricular fibrillation (VF), in which the heart quivers and no longer pumps blood. It will not shock a normal heartbeat, or a flat line with no electrical activity at all.
The Australian and New Zealand Committee on Resuscitation (ANZCOR) says that CPR alone will not save someone in VF, and that survival drops by about 10% for every minute defibrillation is delayed. For this reason, the final step in the DRSABCD action plan, which stands for Danger, Response, Send for help, Airway, Breathing, CPR and Defibrillation, is to attach an AED as soon as one arrives.
How do you use an AED?
Switch it on and do what it tells you. AEDs give spoken instructions for every step, and most also have pictures or a screen showing what to do.
CPR needs to keep going until the AED is on and the pads are attached. If there are two of you, one person keeps pushing while the other sets up the AED. If nobody has called Triple Zero (000), call now on speaker so that the call-taker can talk you through CPR and the AED.
How do you prepare the chest for AED pads?
Expose the whole chest and make sure that the skin is dry, so that the pads can stick firmly.
- Cut or pull clothing off the chest, including a bra.
- Wipe the chest dry if it is wet or sweaty.
- Shave a small patch only if thick chest hair would stop a pad sticking.
If the AED has a prep kit, use the scissors and razor in it, but do not let this delay the shock.
Where do AED pads go on an adult?
One pad goes just below the right collarbone and the other on the left side of the chest, below the armpit. This is ANZCOR's standard adult position, which puts the heart between the pads so that the shock passes through it.
Match each pad to the diagram on it, peel off the backing and press it down firmly. If the person has large breasts, place the left pad to the side of the breast, avoiding breast tissue.
Why does an AED say 'stand clear'?
The AED says this because it is analysing the heart rhythm, and touching the person can interfere with the reading. Stop CPR when it tells you to, say 'stand clear' out loud and hold your hands up so that others keep off too.
'Shock advised' means that it has found a shockable rhythm. 'No shock advised' means that a shock will not help right now. It does not mean that the person has recovered, so you need to go straight back to CPR, and the AED will recheck the rhythm in about two minutes.
Do you have to press the shock button?
You only have to press it on a semi-automatic model, and even then the AED decides whether a shock is needed. When it advises one, check that nobody is touching the person, including you, and then press the flashing shock button. A fully automatic AED has nothing to press, as it tells everyone to stand clear, counts down and delivers the shock itself.
What do you do after an AED shock?
Restart chest compressions straight away, without pausing to see whether the shock worked. ANZCOR's CPR guideline says not to interrupt compressions to check for a response or breathing, so carry on with 30 compressions to 2 breaths, or compressions only if you cannot give breaths.
Leave the pads on and the AED switched on, because it will stop you about every two minutes to recheck the rhythm and it may advise more shocks.
Keep going until the person responds or breathes normally, a paramedic or other health professional takes over, or you are too exhausted to continue. If they start breathing normally, leave the pads on in case they need another shock.
Can you use an AED on someone who is wet or has a pacemaker?
Yes, with a few precautions.
- Get the person out of the water and dry their chest before attaching the pads. Although ANZCOR says there are no reports of rescuers being harmed by defibrillation in wet environments, nobody should touch the person during a shock.
- Pacemakers and implanted defibrillators sit under the skin of the upper chest, most often on the left. If you can see or feel one, keep the pad at least 8 cm away from it.
- Never put a pad on top of a medication patch, such as a nicotine or pain-relief patch, because it can block the shock and cause small burns. Peel the patch off and wipe the skin first.
Can you use an AED on a child?
Yes. Adult pads are suitable for children over 8. For younger children and babies, use paediatric pads and the AED's child setting where possible, or adult pads if it has neither. If the pads would touch on a small chest, put one on the front and the other on the upper back, between the shoulder blades. Our post on infant and child CPR covers what else changes.
Where can you find a public AED in Victoria?
You can search Ambulance Victoria's AED registry, which is available as a map from its Find an AED page. Owners add their AEDs to the registry through GoodSAM, the app that alerts registered responders to nearby cardiac arrests.
Registered AEDs are shared with Triple Zero call-takers, and GoodSAM responders who are alerted to a cardiac arrest receive the location of the nearest one. Because AEDs are only shared while they are accessible, one inside a locked building will not be shared.
It is a good idea to look up the AEDs nearest your home and workplace before you need one. In buildings, check the foyer or reception and look for a green sign with a white heart and lightning bolt. If your workplace owns an AED, make sure to register it and check it monthly, as Ambulance Victoria recommends.
Where can you practise using an AED?
You can practise on a CPR course, using a training AED. Although you do not need training to use a real one, ANZCOR notes that even brief training makes people faster and more accurate with the pads. If you are considering Scope Institute, our HLTAID009 Provide CPR course includes hands-on AED practice, and you are assessed on a training defibrillator and a simulated cardiac arrest. For a team, you are welcome to ask about on-site training at your workplace in metropolitan Melbourne.
Sources
- Guideline 7 – Automated External Defibrillation in Basic Life Support – ANZCOR
- Guideline 8 – Cardiopulmonary Resuscitation (CPR) – ANZCOR
- Basic Life Support flowchart – ANZCOR
- Defibrillators and AEDs – Healthdirect
- How to use an AED – Victor Chang Cardiac Research Institute
- Register my AED – Ambulance Victoria
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