What is a defib?

A defib (or defibrillator) is lunchbox-sized piece of lifesaving equipment used in a First Aid emergency if a person is unconscious and not breathing normally – they are in ‘cardiac arrest’.

A defib can help reset a person’s heart rhythm if their heart is not beating correctly. Using a defib is the final stage of the St John Action Plan DRSABCD (click for plan).

Lifesaving defibrillator. Lunchbox sized:

Click to view the size of a defib

What do they do?

A defib is used when a person is unconscious (unable to be woken), and is not breathing normally.

A defib is used together with cardiopulmonary resuscitation (CPR).

A defib will analyse the heartbeat and shock the heart (only if required) to regain its normal heartbeat. It may take many shocks to successfully achieve a normal heartbeat again.

This is a normal heartbeat:


This is the heartbeat of someone in one type of cardiac arrest:


Are they easy to use?

Yes. Simply turn the defib on and follow the audio instructions, the defib will tell you what to do, how and how often.

WATCH: short video on how easy it is to use a defib.

However, in any First Aid emergency, having the confidence to know what do, when and for how long is crucial. It can be the difference between life and death.

Attendance at an instructor-led training course is the best way to build this confidence to ensure the best possible outcome for an injured person.

Are they expensive?

No. Some defibs cost as little as $2,500, and as a very effective piece of lifesaving equipment, they are invaluable for people who need them. St John sells the Laerdal (Philips) range of defibs, which you can buy here 

Why does my workplace need a defib?

Cardiac arrest can happen to anyone, anywhere, at any time.  Cardiac arrest can strike without any warning, and without immediate resuscitation (CPR and defibrillation), cardiac arrest will lead to death.  All workplaces have a duty of care to their employees, customers and suppliers. 

Can your workplace afford not to have one?


Defibrillator, defib, AED. Are these all the same?

Yes, a defib is short for defibrillator, also known as an AED – Automated External Defibrillator.

Aren't cardiac arrests just heart attacks that happen quickly?

No. A cardiac arrest is caused by a disruption to the heart’s rhythm causing the heart to stop pumping effectively, resulting in a lack of blood and oxygen reaching the brain and other vital parts of the body. Cardiac arrest can occur suddenly and without warning. A person in cardiac arrest becomes unconscious and stops breathing normally. As soon as you recognise this immediately call 000 (triple zero), perform CPR and use a defib, where available.

Learn the signs of cardiac arrest:

– Unconscious (unable to be woken)?

– Not breathing normally or only gasping?

Survival from cardiac arrest depends on immediate resuscitation (CPR).

A heart attack occurs when a blockage of an artery stops blood from reaching parts of the heart muscle, depriving it of blood supply. As a result, part of your heart muscle starts to die.

The longer the blockage is left untreated the more heart muscle is damaged. A person is still conscious (awake) and still breathing during a heart attack, however, if untreated this can cause cardiac arrest. If you recognise warning signs of a heart attack, call 000 (triple zero) immediately.

Learn the signs of heart attack, which include:

– Aches, discomfort or pain in your jaw and tightness in your chest

– Nausea, dizziness and/or a cold sweat

– Shortness of breath

Most importantly, heart attacks can be prevented by consulting your doctor to assess your risk category. Time to respond is critical.

Unfortunately, many cardiac arrests cannot be prevented and can happen to anyone, anywhere, anytime. For this reason alone, St John encourages workplaces, sporting clubs and other public places to have access to a defib, with people nearby that know how to respond in an emergency.

Defibs save lives.

Can defibs shock people at random?

No. A defib will only shock if it detects an irregular heart beat (called a shockable rhythm). They will not shock someone who doesn’t need it – ever.

How much maintenance will our defib need?

Defibs require extremely low maintenance, all have an indicator light showing an operational status of green (ready) red (not ready). Most defibs will only ‘beep’ if they require attention and it can be simple as pressing the flashing ‘info’ button to determine what needs replacing.

How long do the pads last?

Pads last for 2 ½ years. They can be purchased online here and are user replaceable by simply unplugging the old pads and plugging in the new pads – similar to charging a mobile phone or connecting your TV to a DVD player.

How long does the battery last?

Defib batteries last up to 4 years. They are user replaceable items and can be purchased online here.

Where can I learn about using a defib?

St John Ambulance run training courses run every week all around Australia. Find your next course date here or by calling 1300 STJOHN (78 56 46).