AED pad placement: how to use an AED

Turn the AED on first, then do exactly what its voice tells you.

A close-up shot of a wall-mounted AED device. — Photo: Vladimir Srajber / Pexels

Area: SafetyFrom age 12Time to learn: 15 minutes to read; one CPR and AED class for hands-on practicePractise in a class

An AED (automated external defibrillator) talks you through every step. Your job is to turn it on, put the pads on the bare chest where the pictures on the pads show, keep everyone clear when it analyzes or shocks, and do CPR between prompts.

SafetyThis lesson does not replace hands-on training. Take a CPR and AED course from the American Heart Association, the American Red Cross, Heart & Stroke or the Canadian Red Cross. AED models differ, so always follow the voice prompts of the one in front of you.

Why it matters

An AED reads the heart rhythm of a person in cardiac arrest and gives a shock only if the rhythm needs one, so a bystander can act before paramedics arrive. Doing CPR and using an AED can double a person's chance of survival. Yet in 2024, among arrests in public places recorded by the US CARES registry, a bystander applied an AED in only 12.6%. Pads that are badly placed, touching each other, or stuck over clothing or a medication patch can make the shock less effective.

How to do it

If someone collapses and is not breathing normally, call 911, shout for someone to bring the AED, and start hands-only CPR until it arrives.
Turn the AED on by opening the lid or pressing the power button. From this point, follow its voice and screen.
Bare the chest. Remove any clothing, jewelry and medication patches that the pads could touch. If the person is lying in water, pull them clear. Dry the chest, and if hair would keep the pads from sticking, shave it with the razor in the AED kit.
Place the pads for an adult, matching the pictures on the pads. Put one pad on the upper right chest, just below the collarbone. Put the other on the left side of the ribs, below the armpit and level with the bottom of the chest muscle; on a woman, it goes under the breast.
If you see a small scar and a lump under the skin of the chest (a pacemaker or implanted defibrillator), place the pad about 1 inch (2.5 cm) away from the lump.
For a child under 8 years old or under 55 lb (25 kg), use child pads if the kit has them. If you have only adult pads, use them, keeping them at least 1 inch (2.5 cm) apart. If the chest is too small for that, put one pad on the front of the chest and one on the back.
Plug the pad cable into the AED if it is not already connected. When the AED says it is analyzing, stop CPR and make sure no one is touching the person.
If the AED advises a shock, say 'Clear', check that no one is touching the person, and press the shock button when it tells you to. Some AEDs give the shock on their own after a countdown.
Restart CPR immediately after the shock, or as soon as the AED says no shock is advised. Leave the pads on and keep following the prompts until paramedics take over.

Common mistakes

Hesitating to switch the AED on because you are not sure it is needed. The AED checks the heart rhythm itself and advises a shock only when one is needed.
Letting the pads touch each other, or putting them over clothing, a medication patch or a pacemaker lump.
Touching the person, or letting anyone else touch them, while the AED is analyzing or shocking.
Stopping CPR for long stretches while you set up. Keep up compressions until the AED tells you to stop.

You can do this when …, without looking at this page, you can turn on a training AED, place both adult pads correctly on a training manikin, and explain what changes for a child.

Reading is not training. Practise on a manikin or in a supervised class with the American Red Cross or the American Heart Association, or in Canada with the Heart and Stroke Foundation, St John Ambulance or the Canadian Red Cross.