If someone has a cardiac arrest, a defibrillator can help restore their normal heart rhythm while you’re waiting for the emergency services to arrive.

More than 30,000 people have an out-of-hospital cardiac arrest in the UK every year. Defibrillators are currently used in less than 1 in 20 cardiac arrests.  

A cardiac arrest is when someone’s heart stops beating. It’s a medical emergency and every second matters. Anyone can have a cardiac arrest.  

In the UK, fewer than 1 in 10 people survive an out-of-hospital cardiac arrest. Chances of survival decrease by up to 10% for every minute that passes without medical help.  

When someone has a cardiac arrest, 4 things need to happen to give them the best chance of survival.  

These 4 actions are called the ‘chain of survival’. 

They are:  

1. Early recognition and call for help: know when cardiac arrest is happening and call 999.  
2. Early CPR: deliver chest compressions to save the person’s life. This is called ‘cardiopulmonary resuscitation,’ or CPR.
3. Early defibrillation: shock the heart using a defibrillator. Every second counts so this should happen as soon as possible. A quick response gives someone the best chance of survival.  
4. Post-resuscitation care: this is what happens once the person has been resuscitated and is in the care of medical professionals.  

A defibrillator is a portable device that delivers a controlled electric shock safely. It tries to get the heart to beat normally again when someone has had a cardiac arrest.

You may hear people call defibrillators a PAD or AED.  

• PAD stands for ‘public access defibrillator’.
• AED stands for ‘automated external defibrillator’.  

You can use either type of defibrillator if someone has a cardiac arrest.  

Defibrillators are easy to use, even if you’ve not had training. The emergency operator will talk you through what to do. Many defibrillators will tell you what you need to do and when to do it. There are two steps to using a defibrillator.  

1. You put the defibrillator pads on the person’s chest.  
2. The defibrillator checks their heart rhythm and delivers a shock if they need one.  

Some defibrillators do this automatically, while some will tell you to press a button to deliver the shock.

Next: Do you need a defibrillator? →