How to use a defibrillator (AED): step-by-step
Reading time: approximately 5 minutes
You are in an arena, a shopping mall, or an office. Someone collapses, becomes unresponsive, and is not breathing normally. On the wall, there is a cabinet with a green heart symbol. Many people hesitate to open it, fearing they might do something wrong. It is precisely this hesitation that costs lives. Learning how to use a defibrillator (AED) takes less time than reading this article, because the device does almost all the work: it analyzes, it speaks, and it refuses to deliver a shock if the heart does not need one. Here is the complete sequence, in order.
What an AED does — and what it cannot do
An automated external defibrillator is a portable device that analyzes heart rhythm and, if necessary, delivers an electric shock to help a stopped heart resume a normal rhythm.
The distinction is important: CPR circulates blood and oxygen, but it does not restart the heart. The AED, however, can do that. The two are complementary, never interchangeable.
According to the Heart and Stroke Foundation, approximately 60,000 cardiac arrests occur outside of a hospital each year in Canada — one every nine minutes. Without immediate intervention, nine out of ten of these arrests are fatal. Performing CPR and using an AED can double a person's chances of survival.
Recognizing cardiac arrest in three seconds
Before looking for the AED, confirm the situation. A person in cardiac arrest:
- has suddenly collapsed;
- is unresponsive to touch or voice;
- is not breathing, or breathing abnormally — loud, irregular gasps, known as agonal breathing, do not count as breathing.
If these three elements are present, do not wait for anything else. Time is the only factor you control.
The complete sequence, step by step
1. Call 911 and shout for someone to bring you an AED. Put your phone on speakerphone. If someone else is present, clearly designate them: "You, go get the defibrillator." A named instruction is executed; a "can someone go?" is not.
2. Begin CPR immediately. Compressions in the center of the chest, firm and fast, without waiting for the device. Continue until the AED is ready for use.
3. Turn on the AED. Depending on the model, lift the cover or press the power button. All AEDs then give clear voice instructions. Listen to them and follow them: they are designed for someone who has never touched the device.
4. Expose the chest and apply the pads. Remove clothing, as well as jewelry and medicated patches that might come into contact with the pads. Stick the pads on the bare skin, exactly as shown in the illustrations printed on them. If the chest is wet, wipe it dry; if it is very hairy, quickly shave the area if a razor is available in the AED kit.
5. Let the device analyze — and do not touch the person. Say it out loud: "I'm going to deliver a shock, do not touch the victim." Make sure visually that no one is in contact with them.
6. Press the shock button if the device prompts you to. Some models trigger automatically. If the AED determines that no shock is necessary, it will not administer it — you cannot harm the person with this device.
7. Resume CPR immediately, starting with compressions, whether a shock was administered or not. Leave the pads in place and continue to follow the voice prompts until emergency medical services take over or the person starts breathing normally again.
Questions everyone asks
Do you need to be trained to use it? No. Anyone can use an AED, and it's always better to try than to do nothing. However, CPR and AED training makes you much faster and calmer on the day it counts, because you won't have to figure out the device under stress.
What about for a child? Most AEDs offer a pediatric mode or specific pads for children. Follow the device's instructions. In the absence of pediatric pads, adult pads are used rather than doing nothing: on a small chest, place one in front and one on the back so they do not touch.
On a wet or metal surface? Move the person to a dry surface if possible quickly, and wipe the chest dry before applying the pads.
Maintaining your defibrillator so it's ready for use
A defibrillator is not something you install and forget about. Two consumables have an expiration date: the battery and the pads. A device with expired pads is a device that will let you down.
- Check the device's status indicator monthly.
- Note the expiration dates of the battery and pads in your calendar.
- Keep a spare set of pads, including pediatric pads if your environment hosts children.
- Ensure the location is clearly marked and accessible at all times, without a key.
- Register the device's location with your regional 911 service.
Our defibrillators and their spare parts are available with corresponding batteries and pads. To understand the obligations and best practices in a business setting, read our guide on AEDs in the workplace.
What to remember
The life-saving sequence consists of three steps: call 911 and have an AED brought, start CPR without waiting, use the AED as soon as it arrives. Turn it on, apply the pads to bare skin, move away during analysis, press the shock button if the device prompts you to, then immediately resume compressions. You cannot harm the person: the AED only delivers a shock if the heart needs it. Equip your environment with an AED defibrillator and take an online CPR and AED training — it's the combination that transforms a bystander into a lifesaver.
Sources: Heart and Stroke Foundation — How to use an automated external defibrillator (AED) · CCOHS — First Aid: Information on Automated External Defibrillators
This article is for educational purposes only. In case of emergency, call 911.