How do you use an automated external defibrillator (AED)?

Many companies, public spaces and buildings are equipped with automated external defibrillators (heart defibrillators) nowadays. These devices are easy to use, even if you haven’t ever come across one before. Defibrillators can often be recognized as such based on the abbreviation “AED” and/or a green sign with a heart symbol on it.

How do automated external defibrillators work?

Put simply, an AED is a box with a handle and a case, and it looks a bit like a first aid kit or a small tool box. The box has two cables attached to it, each with a postcard-sized sticker on the end of it (the electrodes). The electrode pads connect the device to the unconscious person.

Defibrillators are easy to use: The box gives spoken instructions, telling you what to do and in which order. Depending on the model, there may also be a small screen or diagrams to help you understand what to do.

When used properly, AEDs recognize two typical conditions of the heart that can make people lose consciousness and stop breathing, and can react accordingly:

  • Ventricular fibrillation: Here the heart muscle still contracts, but far too fast and in a chaotic way. As a result, the heart “twitches” rather than pumping, so it is no longer able to pump blood around the body. By exposing the heart to a controlled electric shock, defibrillators can restore a normal heartbeat, making the heart pump effectively again.
  • Asystole (no heart activity): Here the heart muscles stop contracting completely, and the heart stops pumping. Applying an electric shock won’t help in this case. Cardiac compressions are needed instead. The defibrillator then helps by giving spoken instructions.

Illustration: Defibrillator: a) Example of storage location, b) Taking out the AED case, c) An open AED case with adhesive electrode pads

Defibrillator: a) Example of storage location, b) Taking out the AED case, c) An open AED case with adhesive electrode pads

When are defibrillators used?

You should use a defibrillator if you are resuscitating an unconscious person with the help of others. You can then share the different tasks: One person can start doing chest compressions, while the other person (or people) call for an ambulance and get the defibrillator.

If you are alone, call for an ambulance first and then immediately start doing chest compressions.

How are defibrillators used?

As soon as you get hold of a defibrillator, you have to turn it on and connect it. It’s important to continue doing chest compressions until the device tells you to stop. Work together: One person can do chest compressions, while another person sticks the two electrodes on the naked chest of the unconscious person. One of the electrodes should be placed under the right collarbone, and the other should be placed on the left side of the chest – under the armpit. Then follow the spoken instructions given by the device.

Illustration: Using a defibrillator: a) Placing electrodes on chest and doing chest compressions, b) Pressing the shock button, making sure not to touch the unconscious person

Using a defibrillator: a) Placing electrodes on chest and doing chest compressions, b) Pressing the shock button, making sure not to touch the unconscious person

If the defibrillator recognizes that someone’s heart is fibrillating, it will ask you to press the shock button to produce an electric shock. The shock button often has a “lightning” symbol on it. Follow the spoken instructions given by the device. It’s important to make sure that neither you nor anyone else is touching the unconscious person when the shock button is pressed. Continue to follow the instructions given by the defibrillator afterwards – for instance, the device may tell you to do chest compressions again.

Deutsche Gesetzliche Unfallversicherung (DGUV). DGUV-Information 204-010: Automatisierte Defibrillation im Rahmen der betrieblichen Ersten Hilfe. November 2014.

Perkins GD, Handley AJ, Koster RW, Castrén M, Smyth MA, Olasveengen T et al. European Resuscitation Council Guidelines for Resuscitation 2015: Section 2. Adult basic life support and automated external defibrillation. Resuscitation 2015; 95: 81-99.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

Comment on this page

What would you like to share with us?

We welcome any feedback and ideas. We will review, but not publish, your ratings and comments. Your information will of course be treated confidentially. Fields marked with an asterisk (*) are required fields.

Please note that we do not provide individual advice on matters of health. You can read about where to find help and support in Germany in our information “How can I find self-help groups and information centers?

Created on November 2, 2017
Next planned update: 2021

Authors/Publishers:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

How we keep you informed

Follow us on Twitter or subscribe to our newsletter or newsfeed. You can find all of our films online on YouTube.