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In Australia, sudden cardiac arrest is one of the leading causes of death, which can affect people of any age, anywhere, at any time. It is estimated that approximately 15,000 people die from sudden cardiac arrest in Australia each year1a statistic we hope to improve through increased awareness of and access to Automatic External Defibrillators (AEDs).


If an AED is applied within the first few minutes of a cardiac arrest, survival rates can increase from 10% to as high as 70%. This is the only definitive treatment for cardiac arrest, highlighting how crucial it is to have access to an AED in such an emergency.


Below we have answered some of the most commonly asked questions about AEDs so you will have the confidence to understand better how to help someone experiencing a sudden cardiac arrest.


1. What does ‘AED’ stand for?

‘AED’ stands for Automatic External Defibrillator – also known as a defibrillator or ‘defib’.


2. What is an AED?

An AED is an automated, accurate medical device that analyses a person’s heart rhythm and recognises whether it requires a shock. AEDs are essential for increasing survival rates of sudden cardiac arrest.


3. What is defibrillation?

Defibrillation is the process of attempting to restore the heart’s normal rhythm. During a cardiac arrest, electrical activity in the heart muscle is interrupted, causing an irregular heart rhythm and preventing the heart from beating and pumping blood normally.


4. What does an AED do?

An AED delivers a brief electric shock to the heart after analysing an abnormal heart rhythm. The AED will determine whether a shock is needed via the adhesive electrode pads on the patient’s chest. The shock aims to restore the heart’s normal electrical rhythm and allow it to start beating again.


5. How does the AED work?

Once the AED has identified an abnormal heart rhythm from the electrode pads on the patient’s chest, it will deliver an electric shock. This shock interrupts the chaotic, irregular rhythm the heart has been in and gives it a chance to return to its normal rhythm and pump blood around the body again.


6. How do I use an AED?

Using an AED is very simple – anyone can use one, and no training is required. Once you open the case and turn the device on, it will automatically start to give voice prompts instructing you what to do.


To further increase survival rates, CPR should also be performed while someone else is retrieving the AED. This will give a better chance of keeping the heart in ‘fibrillation’ or a ‘shockable rhythm’.


7. Is an AED dangerous to use?

No – the AED assesses the patient’s heartbeat to determine whether a shock is needed. If the heartbeat is normal, the AED will say ‘do not shock’. If the heartbeat is abnormal, the device will advise you to press the shock button. The AED will not shock someone who does not require it.


8. Do I need training to use an AED?

No – anyone can use an AED. The voice prompts given by the machine will tell you exactly what to do.

However, St John encourages First Aid and AED training to increase your confidence in using an AED, and can perform CPR while another is retrieving an AED. First Aid training also helps people understand where the AED fits into the DRSABCD process and the Chain of Survival. 


9. Can AEDs be used on children?

Yes – standard adult AED pads are used on children over 8 years. There are separate children’s pads for children under 8 years. The placement of these electrode pads is different to adults, as instructed by the graphics on the pads. Some AEDs even have a child-safe mode that adjusts the strength of the electric shock to suit a child. It is not recommended to use an AED on children aged less than 1 year.


10. Can AEDs be used on pregnant women?

Yes, it is safe to use an AED on a pregnant woman.



Having an AED close by in your workplace or community club can make all the difference for surviving a cardiac arrest by giving early access to defibrillation, and therefore the best chance of survival.


St John Ambulance Australia has an AED register and as part of best practice First Aid, St John promotes the importance of saving lives through resuscitation training and making defibrillators more accessible to the public. Share your AEDs life-saving power with others and register (if suitable) your publicly accessible defibrillator with St John. Once registered, the location of your defibrillator will be made available by the St John AED website. To complete an AED Registration, please visit


St John Ambulance (Qld) offers a range of defibrillators and accessories to suit your business and budget. For more information regarding our June 2018 AED* bundle offers, please visit


References: 1, accessed 6 June 2018.

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