Defibrillators · Refresher Guide
AEDs explained: how a defibrillator saves a life
A plain-English refresher, featuring CellAED.
From the wall-mounted unit at your gym to a personal device in a kitchen drawer, an AED puts a life-saving shock within reach before an ambulance can arrive. Here is how they work, and how to use one.
- 8 min read
- Aligned to ARC guidelines
- For HLTAID009 / 011 graduates
Without CPR or defibrillation, a person in sudden cardiac arrest can be dead within minutes.
The big picture
The chain of survival
Survival from a sudden cardiac arrest isn’t one action, it’s a sequence, and each link depends on the one before it. It’s one of the most useful mental models to carry out of a first aid course.
Every second counts
For every minute without defibrillation, the odds of survival fall by about 10%.
Drag the timeline to see how fast the window closes. This is why a defibrillator within arm’s reach, not minutes away, changes everything.
at 1 minute without a shock
Don't confuse them
Cardiac arrest vs heart attack
People use these terms interchangeably, but they’re different emergencies, and an AED is for one of them.
A plumbing problem
A blocked artery starves part of the heart muscle of blood. The person is usually conscious and may have chest pain, breathlessness, or arm or jaw pain.
Don’t shock. Call 000, keep them calm and still.
vs
An electrical problem
The heart’s rhythm fails and it stops pumping. The person is unresponsive and not breathing normally.
This is what an AED is for.
A heart attack can trigger a cardiac arrest, which is why recognising the switch, from clutching their chest to collapsed and unresponsive, is critical.
The basics
What is an AED?
An Automated External Defibrillator (AED) is a portable medical device that reads a person’s heart rhythm and, if needed, delivers a measured electric shock to help restore a normal rhythm during sudden cardiac arrest.
The key word is automated. Because they’re designed to be used by ordinary people under pressure, AEDs do the clinical thinking for you. Once the pads are on, the device decides whether a shock will help. You can’t accidentally shock someone who doesn’t need it; if the rhythm isn’t shockable, the AED simply won’t deliver one. That single safety feature is why a bystander with no medical training can use one effectively.
Reads the heart
It analyses the rhythm and decides if a shock is needed, so you don't have to.
Guides you aloud
Clear voice and visual prompts walk you through every step.
Bystander-ready
No medical knowledge required. AEDs now live in gyms, offices, clubs and aircraft.
Under the hood
How does an AED work?
Every AED does the same core job: it delivers a precisely measured shock to a heart in cardiac arrest, aiming to reset the chaotic rhythm so the heart’s natural pacemaker can take over again. Once the pads are on the bare chest, it analyses the rhythm, decides whether a shock is needed, guides you out loud (including telling you to stand clear), and prompts you to continue CPR between rhythm checks.
Voice-guided
Prompts talk you through every step.
Self-deciding
Reads the rhythm and only shocks when it can help.
Bystander-ready
No medical knowledge required.
Recognising the moment
When should you use an AED?
Use an AED as part of DRSABCD when someone shows the signs of sudden cardiac arrest:
No reaction to your voice or a firm shoulder squeeze.
No breaths, or only occasional gasping (agonal) breaths.
The person dropped without warning, with no pulse you can find.
You've called 000, or sent someone to, before you start.
If those boxes are ticked: start CPR, send for the nearest AED, and apply it the moment it arrives.
Hands-on · interactive
How to use any AED
Brands differ, but every AED follows the same pattern. Learn the pattern and you can walk up to almost any unit in the country.
Turn it on
Open the lid or press power. It starts talking immediately.
Expose & prep the chest
Remove clothing and wipe the chest dry. Shave thick hair only if it stops the pads sticking.
Attach the pads
Peel and press firmly onto bare skin, following the pictures on the pads.
Stand clear to analyse
Don't touch the patient while it reads the rhythm.
Shock if advised
Make sure everyone is clear, then press the flashing button (or let an automatic unit deliver).
Resume CPR
Keep going, following the prompts, until the person recovers or help takes over.
The CellAED twist
As simple as Snap, Peel, Stick
A personal unit like CellAED turns those first steps into three quick actions.
Snap
Snap the unit in half to switch it on. It starts talking to you straight away.
Peel
Peel the liner off the two pads to expose the sticky gel surface.
Stick
Stick the pads on the bare chest as the pictures show, then follow the voice.
- Quick note: where do the pads go?
Adults & children over about 8 years (25 kg): one pad on the upper-right chest, one on the lower-left side. Smaller children & infants: use paediatric pads or mode if available; otherwise place one pad on the centre of the chest and one on the back (front to back). Always follow the diagrams printed on the pads.
Quick reference
Do's & don'ts
- Expose and dry the chest before applying pads
- Place pads exactly as the diagram shows
- Stand clear during analysis and shock
- Resume CPR immediately after a shock
- Keep the device findable, in date and known to others
- Don't delay CPR while setting up the device
- Don't touch the patient when told to stand clear
- Don't use on a wet surface or in standing water
- Don't place pads over jewellery or medication patches
- Don't reuse a single-use unit after activation
- Special situations, fast
- Water: move off a wet surface, dry the chest, never in standing water.
- Hairy chest: press pads firmly; shave only if needed.
- Pacemaker lump: place the pad about 8 cm to the side.
- Metal: no one touching the patient during a shock.
- Medication patch: remove it and wipe the skin.
- Pregnancy: use as normal, it's safe and recommended.
Don't skip this
Does this make CPR training redundant?
Not at all, for three reasons
Many people wouldn't recognise a cardiac arrest or realise CPR and defibrillation are needed. Training teaches you to spot the signs and act.
Compressions keep blood and oxygen moving to the brain in the critical seconds before a defibrillator is on the chest, and that can decide survival.
Continuing CPR even after an AED is attached is vitally important.
Practice tool · interactive
Find the right compression rhythm
Effective CPR means pushing hard and fast, 100 to 120 compressions a minute, about 5 to 6 cm deep. Start the metronome and push in time. It’s the same beat as “Stayin’ Alive.
Audio plays through your device, turn the volume up. A practice aid, not a substitute for hands-on accredited CPR training.
Spotlight
CellAED, the personal single-use AED
Designed for every home
CellAED is a single-use AED built for the home or to carry while travelling: compact, lightweight, and simple to use whatever your training. While AEDs are already in many public places, CellAED is designed to be affordable enough to eventually sit in every home, like a smoke alarm. It was created in Australia after its founder kept his partner alive with CPR through a cardiac arrest at home, then set out to put a defibrillator within everyone’s reach.
Hand-sized and around 300 g, with no servicing, batteries or gel pads to maintain. It has a fixed product expiry, replace it on or before that date, or when the status light tells you.
Confirm current price, dimensions and shelf life before publishing specific figures.
Myth vs fact · tap to reveal
Clearing up the myths
Common questions
Frequently Asked Questions
Can an AED hurt someone who isn't in cardiac arrest?
No. It analyses the heart rhythm and only shocks when a shockable rhythm is detected.
Do I need training to use one?
AEDs are designed for untrained bystanders, but CPR and AED training means you’ll recognise a cardiac arrest sooner and act faster and more confidently.
Heart attack or cardiac arrest, does the AED tell the difference?
You don’t have to diagnose it. If the person is unresponsive and not breathing normally, apply the AED and let it analyse the rhythm.
Can I use it on a child or baby?
Yes. Use paediatric pads or mode where available. If not, use adult pads following the age and placement guidance above.
What about water, metal, pacemakers or patches?
Dry the chest, avoid standing water and contact with metal during shocks, place pads about 8 cm from a pacemaker, and remove medication patches under pads.
How is CellAED different from the AED on the wall?
It’s personal, single-use and pocket-sized, so it travels with you and can be on a chest within a minute or two, instead of hoping there’s a public AED nearby.
A defibrillator buys time.
Knowing how to use it saves lives.
Book a same-day, nationally accredited CPR or first aid refresher with First Aid Pro and practise compressions, rescue breaths and AED use hands-on with an experienced trainer.
