Collection: The Complete Guide to Defibrillators: Types, UK Law, Costs and How to Choose

Around 30,000 out-of-hospital cardiac arrests occur each year in the UK, and fewer than 1 in 10 people survive. When an automated external defibrillator (AED) is used within the first few minutes, survival rates can climb above 70%. This guide covers everything you need to know about defibrillators: how they work, which type suits your setting, what UK regulations apply, and how to choose the right one for your workplace or community.

What Is a Defibrillator and How Does It Work?

A defibrillator is a medical device that delivers a controlled electrical shock to the heart during a sudden cardiac arrest (SCA). When someone collapses from SCA, their heart enters an abnormal rhythm called ventricular fibrillation, where the heart quivers instead of pumping blood. A defibrillator analyses the heart rhythm, determines whether a shock is needed, and delivers it to reset the heart back to a normal pattern.

Modern public-access AEDs are designed so that anyone can use them, even with no medical training. The device provides clear voice prompts, visual instructions, and in many cases will refuse to deliver a shock unless one is genuinely required. You cannot accidentally harm someone with a properly functioning AED.

What Are the Different Types of Defibrillator?

There are three main categories, each designed for different users and settings.

1. Fully Automatic AEDs

A fully automatic AED analyses the heart rhythm and delivers the shock without the user pressing a button. The device warns bystanders to stand clear and then shocks automatically. This type is ideal for workplaces, schools, and public spaces where the rescuer may be untrained or under extreme stress.

2. Semi-Automatic AEDs

A semi-automatic AED analyses the rhythm and advises the user to press a shock button when a shock is needed. This gives the rescuer a moment to confirm that nobody is touching the patient before delivering the shock. Semi-automatic models are popular with trained first aiders and healthcare professionals who want that extra layer of control.

3. Manual and Professional Defibrillators

Manual defibrillators are used by paramedics, doctors, and advanced clinical staff. They display the ECG rhythm on screen and allow the operator to choose the energy level and timing of each shock. These units often include pacing, 12-lead ECG, and SpO2 monitoring. They are not suitable for untrained bystanders.

Should I Choose a Semi-Automatic or Fully Automatic AED?

The right choice depends on who will be using it and where it will be placed.

Factor	Fully Automatic	Semi-Automatic
Shock delivery	Automatic after warning	User presses button
Best for	Untrained bystanders, schools, public spaces	Trained first aiders, healthcare settings
User confidence needed	Minimal	Moderate
Rescuer control	Less (device decides)	More (rescuer confirms)
Hesitation risk	Eliminated	Possible (user may delay pressing)

For most workplaces and community settings, a fully automatic AED is the safer choice. It removes the risk of hesitation in a high-stress moment. Semi-automatic models are preferred where trained responders want to verify that bystanders are clear before the shock is delivered.

Are Defibrillators a Legal Requirement in the UK?

There is no single UK law that mandates defibrillators in workplaces. However, several overlapping obligations make having one strongly advisable for most employers.

Health and Safety (First Aid) Regulations 1981

Every employer must carry out a first aid needs assessment and provide "adequate and appropriate" first aid equipment. The HSE does not specifically list AEDs, but assessing the risk of cardiac arrest in your workplace is part of this duty. If your premises are large, remote from emergency services, or have high foot traffic, an AED is likely to be considered appropriate.

Duty of Care (Common Law)

Employers owe a duty of care to employees, visitors, and anyone using their premises. The Resuscitation Council UK has noted the "potential consequences for some employers under common law if an AED is not provided." As public awareness of AEDs grows, courts may increasingly view their absence as a failure to take reasonable precautions.

BS 8599-1:2019+A1:2026

The April 2026 amendment to the British Standard for workplace first aid kits raised expectations significantly. It recommends that AEDs should be available in most workplaces with five or more people present, and that the device must be reachable within two minutes from any area of the building. While a British Standard is not law, it represents best practice. Enforcement bodies and insurers increasingly reference it when assessing compliance.

Schools

All state-funded schools in England have received a free AED through the Department for Education programme. Independent schools and early years settings are strongly encouraged to have one.

How Much Does a Defibrillator Cost in the UK?

The total cost of ownership includes the device, storage, and ongoing consumable replacements.

Item	Typical Cost (ex. VAT)	Replacement Frequency
Public-access AED unit	£700 to £1,800	One-off purchase
Professional/clinical AED	£1,800 to £4,000+	One-off purchase
Indoor cabinet or wall bracket	£20 to £350	One-off
Heated outdoor cabinet	£400 to £700	One-off (plus electricity)
Replacement electrode pads	£35 to £155	Every 2 to 4 years
Replacement battery	£50 to £350	2 to 3 times over 10 years
AED signage	£5 to £37	One-off

At Vena Cava, our public-access AEDs start from £774 (ex. VAT) for the ViVest PowerBeat X1, with fully automatic options such as the Lifepak CR2 at £949.99 and the Zoll AED Plus at £1,462.99. We also carry indoor cabinets from £77.99 and heated outdoor cabinets from £589.99.

Where Should You Place a Defibrillator?

Placement is as important as the device itself. A defibrillator locked in a cupboard or placed in an obscure corridor will not save a life.

Key placement principles:

• Visibility: Mount the AED at chest height in a high-traffic area such as a reception, lobby, or main corridor. Use clear AED signage to mark its location.
• Accessibility: The device should be reachable within two minutes from any part of the building (BS 8599-1:2019+A1:2026 guidance). Larger buildings may need multiple units.
• No locked barriers: Avoid placing the AED behind locked doors, in staff-only areas, or in rooms that are inaccessible outside business hours if the building is used 24/7.
• Environmental protection: Indoor devices need a simple wall bracket or cabinet. Outdoor installations require a weatherproof, heated cabinet to protect the electronics and pads from temperature extremes and moisture.

How Do You Use a Defibrillator? (Step by Step)

Using an AED does not require medical training. Follow these steps:

Step 1: Call 999
If someone collapses, is unresponsive, and is not breathing normally, call 999 immediately (or ask a bystander to call). The ambulance dispatcher can guide you through the process.

Step 2: Start CPR
Begin chest compressions at a rate of 100 to 120 per minute, pressing down 5 to 6 centimetres on the centre of the chest. CPR keeps blood flowing to the brain and vital organs until the AED is ready.

Step 3: Switch on the AED
Turn on the device (some activate when you open the lid). It will begin giving voice instructions immediately.

Step 4: Attach the pads
Peel the adhesive pads from their packaging and place them on the patient's bare chest as shown on the diagrams. One pad goes below the right collarbone, the other on the left side beneath the armpit. The device will pause CPR to analyse the heart rhythm.

Step 5: Follow the prompts
If a shock is advised, the device will either deliver it automatically (fully automatic) or tell you to press the shock button (semi-automatic). Ensure nobody is touching the patient. After the shock (or if no shock is advised), resume CPR as directed until paramedics arrive.

How Do You Maintain a Defibrillator?

AEDs are low-maintenance devices, but they do require regular checks to stay rescue-ready.

• Weekly visual check: Confirm the status indicator light is green (or shows a tick). A red light or warning symbol means the device needs attention.
• Electrode pad expiry: Check the expiry date on the pads every month. Replace them before they expire, as dried-out pads may not adhere properly or conduct the shock effectively.
• Battery monitoring: Most modern AEDs run daily or weekly self-tests and will alert you when battery power is low. Batteries typically last 4 to 5 years on standby.
• Software updates: Some models (such as the Lifepak CR2) support USB data transfer for firmware updates and post-event data review.
• Record keeping: Maintain a simple log of your checks. This demonstrates due diligence and supports compliance with your first aid needs assessment.

Do You Need Training to Use a Defibrillator?

No formal training is required to use a public-access AED in the UK. The devices are designed to be used by complete beginners, with voice prompts guiding every step. You cannot deliver a shock to someone who does not need one, as the device analyses the heart rhythm and will only allow a shock for a shockable rhythm.

That said, training builds confidence and reduces hesitation. A half-day first aid course covering CPR and AED use costs between £50 and £150 per person and can be delivered on-site. The Resuscitation Council UK, British Heart Foundation, and St John Ambulance all offer accredited courses. Even a free 15-minute online refresher can make a significant difference in an emergency.

Can You Use a Defibrillator on a Child?

Yes. Most modern AEDs can be used on children over 1 year of age. Many models include a paediatric mode (activated by a switch or by using smaller child pads) that reduces the energy delivered to a level appropriate for a child's body. The Lifepak CR2, for example, includes a built-in child mode that can be activated without changing the pads.

If child-specific pads are not available, adult pads can be used on a child. Place one pad on the chest and one on the back to avoid the pads overlapping. Using an AED on a child who needs it is always better than not using one at all.

How to Choose the Right Defibrillator for Your Setting

Consider these factors when selecting an AED:

• Who will use it? Untrained staff or members of the public should have a fully automatic model. Trained first aiders may prefer semi-automatic for the added control.
• Where will it be stored? Indoor settings need a wall bracket or cabinet. Outdoor or exposed locations require a heated, weatherproof cabinet with an IP65 or higher rating.
• Paediatric capability: Schools, nurseries, and family-oriented venues should choose a model with a built-in child mode or ensure child pads are available.
• Self-testing: Look for models that run automatic daily or weekly self-checks and display a clear ready/not-ready indicator. This reduces the maintenance burden.
• Consumable availability: Check that replacement pads and batteries are readily available and affordable for your chosen model. Some manufacturers bundle pads and battery into a single replacement cartridge for convenience.
• Budget: Factor in the total cost of ownership over 10 years, including 2 to 3 battery replacements and 3 to 5 sets of pads, not just the upfront device cost.

Frequently Asked Questions

Can a defibrillator restart a stopped heart?

A common misconception. An AED treats ventricular fibrillation (a chaotic, quivering rhythm), not a flatline (asystole). It resets the abnormal rhythm so the heart can resume its normal pattern. CPR is still essential to maintain blood flow while the AED prepares to shock.

Can you be sued for using a defibrillator on someone?

In the UK, the Social Action, Responsibility and Heroism Act 2015 protects people who act in good faith during an emergency. No bystander in the UK has ever been successfully sued for using an AED. The greater legal risk is in failing to provide one when a reasonable employer should have done so.

How long do defibrillator pads last?

Unopened electrode pads typically have a shelf life of 2 to 4 years, depending on the manufacturer. Check the expiry date monthly and replace them before they expire. At Vena Cava, we stock replacement electrode pads for most major AED brands.

Do defibrillators need servicing?

Most public-access AEDs are designed to be maintenance-free beyond replacing pads and batteries. They run automatic self-tests (daily or weekly) and display a ready indicator. A weekly visual check and a monthly pad-expiry check are all that is needed.

What is the difference between cardiac arrest and a heart attack?

A heart attack occurs when blood flow to part of the heart is blocked (a plumbing problem). A cardiac arrest occurs when the heart suddenly stops pumping effectively (an electrical problem). A heart attack can sometimes trigger a cardiac arrest, but they are different conditions. A defibrillator is used for cardiac arrest, not a heart attack.

Where can I register my defibrillator so the ambulance service knows about it?

Register your AED on The Circuit (thecircuit.uk), the national defibrillator network database. When someone calls 999, the ambulance service can direct the caller to the nearest registered AED. Registration is free and takes about five minutes.