Automated External Defibrillators, usually called AEDs or defibrillators, can play a vital role when someone has a sudden cardiac arrest.
You may see defibrillators in workplaces, schools, gyms, shopping centres, community buildings and outdoor cabinets across the UK. However, simply having more defibrillators available does not save lives. Someone needs to recognise cardiac arrest, call 999, start CPR, locate the AED and use it as quickly as possible.
Current UK statistics show why those first few minutes matter so much.
How Many Cardiac Arrests Happen in the UK Each Year?
More than 40,000 out-of-hospital cardiac arrests occur in the UK each year, according to current figures published by the British Heart Foundation.
Fewer than one in ten people survive an out-of-hospital cardiac arrest in the UK.
A cardiac arrest means the heart has suddenly stopped pumping blood effectively around the body. The person will become unresponsive and will not be breathing normally.
This is different from a heart attack. A heart attack happens when the blood supply to part of the heart muscle becomes blocked. A heart attack can lead to cardiac arrest, but the two conditions are not the same.
When cardiac arrest occurs, immediate action can make a significant difference.
The Resuscitation Council UK adult basic life support guidelines emphasise the importance of early recognition, calling 999, CPR and using an AED.
How Often Are AEDs Used in Cardiac Arrests?
Despite the increasing number of public access defibrillators around the UK, AED use before the ambulance service arrives remains relatively uncommon.
Resuscitation Council UK’s 2025 cardiac arrest epidemiology data reports bystander AED use rates of:
- 9.0% in England
- 8.0% in Northern Ireland, based on January to March 2025 data
- 10.3% in Scotland
- 8.4% in Wales
This means a bystander AED was used in only around one in ten out-of-hospital cardiac arrests, or fewer, depending on the UK nation.
That represents an important opportunity to improve survival.
How Much Difference Can an AED Make?
Timing is critical.
Resuscitation Council UK states that defibrillation within three to five minutes of collapse can produce survival rates as high as 50% to 70% in adults experiencing cardiac arrest.
Current UK guidelines also state that bystander CPR and AED use can increase the chance of survival two to four-fold.
These figures do not mean that using an AED guarantees survival. The person’s underlying condition, heart rhythm, how quickly someone recognises the cardiac arrest and several other factors can affect the outcome.
What they demonstrate is the importance of acting quickly.
Waiting for an ambulance before starting CPR or attempting to find an AED loses valuable time.
Why Does Early Defibrillation Matter?
During some cardiac arrests, the heart develops an abnormal electrical rhythm that prevents it from pumping blood effectively.
An AED analyses the heart’s electrical activity and determines whether a shock may help.
If the AED identifies a shockable rhythm, it instructs the rescuer to deliver a shock. The shock aims to allow the heart’s normal electrical activity to resume.
An AED will not simply shock everyone it is attached to.
The machine analyses the heart rhythm and only advises a shock when appropriate.
That makes modern AEDs suitable for members of the public to use.
Does Every Cardiac Arrest Need an AED Shock?
No.
Not every cardiac arrest has a shockable heart rhythm.
However, you cannot determine this simply by looking at the casualty.
If someone is unresponsive and not breathing normally, call 999, start CPR and send someone to get an AED if one is available.
Attach the AED as soon as possible and follow its instructions.
The AED will analyse the casualty’s heart rhythm and tell you whether it recommends a shock.
If it does not recommend a shock, continue CPR and follow the AED prompts.
Can Anyone Use a Defibrillator?
Yes.
You do not need to be a doctor, paramedic or trained first aider to use a public access AED.
Resuscitation Council UK states that AEDs can be used safely and effectively by people without previous training.
Once switched on, the AED provides spoken and/or visual instructions that guide you through the process.
This is an important message because fear and lack of confidence can prevent people from acting.
If somebody needs CPR and defibrillation, doing something is far better than standing back because you are worried about making a mistake.
You can read more in the Resuscitation Council UK guidance on defibrillation.
How Many Public Defibrillators Are Registered in the UK?
The UK now has a national public access defibrillator network called The Circuit.
According to Resuscitation Council UK’s 2025 epidemiology guidance, by mid-June 2025 there were 108,584 AEDs registered on The Circuit.
Registration matters because ambulance services need to know where defibrillators are located.
When someone calls 999 about a suspected cardiac arrest, an ambulance call handler may be able to direct a bystander to a nearby registered AED.
A defibrillator that nobody can find during an emergency cannot fulfil its potential.
Organisations responsible for public access AEDs should therefore make sure their device is registered and its details remain up to date.
You can find information about registering a defibrillator through The Circuit.
What Should You Do If Someone Has a Cardiac Arrest?
If you find someone who is unresponsive and not breathing normally:
- Call 999 immediately and put the phone on speaker if possible.
- Start CPR.
- Send someone to find an AED if one is available.
- Continue CPR while someone retrieves the AED.
- As soon as the AED arrives, switch it on.
- Expose the casualty’s chest and attach the pads as shown on the AED.
- Follow the AED’s spoken or visual instructions.
- Make sure nobody touches the casualty while the AED analyses the heart rhythm.
- Deliver a shock if the AED tells you to do so.
- Immediately resume CPR when instructed.
Continue until the casualty shows signs of life, professional help takes over or you become unable to continue.
If you are on your own, the 999 call handler can guide you through CPR and help identify whether a registered defibrillator is nearby.
Where Should AED Pads Be Placed?
For an adult, remove clothing from the chest and apply the pads to bare skin.
AED pads normally show a diagram indicating exactly where to position them.
Typically, one pad goes on the upper right side of the chest below the collarbone and the other goes on the left side of the chest below the armpit.
If the chest is wet, dry it quickly before attaching the pads.
If excessive chest hair prevents the pads from sticking properly, you may need to shave the areas where the pads will sit. Do not unnecessarily delay defibrillation.
Once attached, follow the AED’s instructions.
What If I Put the AED Pads the Wrong Way Around?
Do not waste valuable time removing correctly attached pads simply because you have placed them the opposite way around.
The current Qualsafe first aid guidance used within our training states that the AED will still work if the two pads have accidentally been placed the wrong way around.
The priority is to minimise interruptions to CPR and deliver defibrillation as quickly as possible when the AED recommends it.
Should Workplaces Have an AED?
UK workplaces do not automatically have a legal requirement to provide an AED simply because they employ staff.
However, organisations should consider AED provision as part of their wider first aid and risk management arrangements.
Factors can include the number and age profile of people on site, workplace activities, location, access for emergency services and the distance to an existing publicly accessible AED.
Resuscitation Council UK provides specific guidance on considering an AED as part of a first aid needs assessment.
Having an AED on site can reduce the time between cardiac arrest and attempted defibrillation.
AEDs Need to Be Ready for an Emergency
Installing an AED is only the beginning.
Someone should take responsibility for checking the device and making sure it remains ready for use.
Checks should follow the manufacturer’s instructions and include things such as:
- The AED’s readiness indicator
- Battery condition or expiry
- AED pad expiry dates
- Damage or missing equipment
- Accessibility of the AED
- Cabinet condition where applicable
- Clear signage
Public access defibrillators should also be registered on The Circuit and their status kept up to date.
An AED needs to be accessible and rescue-ready when somebody needs it.
AED Usage Statistics: The Numbers That Matter
The statistics tell a straightforward story.
More than 40,000 people experience an out-of-hospital cardiac arrest in the UK each year, yet fewer than one in ten survive.
Bystander AED use currently occurs in only around 8% to 10% of cases across the UK nations.
However, defibrillation within three to five minutes can produce survival rates as high as 50% to 70% in appropriate circumstances, and bystander CPR combined with AED use can increase someone’s chance of survival two to four-fold.
There were also more than 108,000 AEDs registered on The Circuit by mid-June 2025.
The problem is therefore not simply about buying more defibrillators.
People need to recognise cardiac arrest, know where AEDs are, have the confidence to retrieve them and, most importantly, use them without delay.
Learn CPR and AED Skills with FAST
An AED is designed so that anyone can use it, even without previous training. However, practical training can give you the confidence to recognise cardiac arrest, perform effective CPR and use a defibrillator without unnecessary delay.
First Aid and Safety Training provides practical, regulated first aid training courses across the North East, including Emergency First Aid at Work, First Aid at Work and Paediatric First Aid.
You can book a first aid course or contact First Aid and Safety Training to discuss training for your workplace or organisation.
You can also find First Aid and Safety Training on Google to view our business information and customer reviews.
