When to use an AED is a question of life and death, and the choice falls to an ordinary bystander. In the minutes between a sudden collapse and the arrival of paramedics, the people standing nearby hold the only tool that can restart a stopped heart. An ordinary person willing to act can be the reason someone survives one of the deadliest emergencies there is.
What is an Automated External Defibrillator?
When to use an AED is the rescuer’s decision; what happens next is the device’s. Once the pads are pressed onto a person’s bare chest, the AED analyses the heart’s electrical rhythm and delivers a shock only when one can correct it. The rescuer never has to judge the heart or decide whether a shock is needed.
The AED speaks a prompt at each step, from placing the AED pads to standing clear before a shock. Each pad has a printed diagram showing where it goes on the chest. AEDs are safe to use, and Australian resuscitation guidance does not limit them to people trained in first aid.
What is Sudden Cardiac Arrest?
Sudden cardiac arrest happens when the heart’s electrical system fails and the heart suddenly stops beating and is unable to pump blood to the brain and the rest of the body within seconds. The person collapses, falls unresponsive, and stops breathing normally, though some take slow, gasping breaths for a short time. This is the single emergency that answers when to use an AED. Every minute without a shock drops a person’s chance of survival by around 10%.
In many cases of cardiac arrest, the heart’s lower chambers quiver rapidly instead of pumping. This state, called ventricular fibrillation, sends no useful blood out of the heart. An electric shock can stop the quiver and let the heart return to a normal rhythm. CPR keeps blood moving to the brain in the meantime, but on its own it cannot restart an irregular heart rhythm.
The DRSABCD Protocol: When to Find an AED
DRSABCD is the standard action plan for first aid in Australia, and it pinpoints when to use an AED within the wider rescue:
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Danger: Check the area is safe for you before you go near the person.
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Response: Squeeze their shoulders and ask loudly whether they can hear you.
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Send for help: Call 000, and send someone to find an AED while you stay with the person.
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Airway: Tilt their head back gently and clear their mouth of anything blocking it.
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Breathing: Look, listen, and feel for normal breathing for up to ten seconds.
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CPR: If they are unresponsive and not breathing normally, start CPR with 30 chest compressions and two breaths.
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Defibrillation: Attach the AED as soon as it arrives and follow its spoken prompts.
The moment to send for an AED comes at the Send step. Start CPR straight away and keep going until the AED is switched on and the pads are attached.
What to Do After Using AEDs
The question of when to use an AED does not end at the first shock. After a shock, return to chest compressions at once and continue CPR. About every two minutes, the AED checks the heart’s rhythm again and either tells the rescuer to stand clear for another shock or to keep going with CPR.
Keep going until the person starts breathing normally on their own, until help arrives and takes over, or until you can no longer continue. If the person wakes and breathes normally, roll them onto their side and keep watching them. Their heart can stop again even after it restarts. Leave the AED pads attached until paramedics take over.
Learn to Use an AED
Anyone can use a defibrillator. When to use an AED is whenever someone collapses from cardiac arrest. With the device handling the shock, the only thing asked of a bystander is speed. Whether you freeze or act in that moment can depend on whether your hands have been through the motions even once before. A CPR course is where you get that first attempt, long before a stranger’s survival ever depends on it. The few hours you spend training in cardiopulmonary resuscitation could be why a stranger’s heart starts again the day it stops.
FAQs
Is Cardiac Arrest the Same as a Heart Attack?
No. A heart attack happens when blood flow to part of the heart muscle is suddenly blocked, usually leaving the person awake and breathing rather than collapsed. Cardiac arrest is different: the heartbeat stops outright, and a heart attack can sometimes set it off.
Can You Use an AED on Children?
Mostly. For a child under eight, use paediatric pads or a paediatric setting if the AED has them; these give a smaller shock suited to a small body. However, using an AED on a child under one year old requires changes to the pads that should only be carried out by a trained medical professional like a paramedic or doctor,
Can You Use an AED on a Pregnant Woman?
Yes. An AED can and should be used on a pregnant woman in cardiac arrest, using the same pads, placement, and prompts as for anyone else.
