A sudden cardiac arrest can happen at work, at school, at the gym, or at home. When a person collapses, is unresponsive, and is not breathing normally or is only gasping, knowing how to use an AED can help you act with purpose while emergency responders are on the way.
An automated external defibrillator, or AED, is designed for use by the public. It gives clear voice prompts, analyzes the heart rhythm, and will only advise a shock when one is appropriate. You do not need to diagnose the person or decide whether they need a shock. Your job is to recognize the emergency, call for help, begin CPR, and follow the AED’s instructions.
First, recognize cardiac arrest and call 911
Check that the area is safe before approaching. Tap the person firmly and ask if they are okay. If they do not respond, look for normal breathing for no more than 10 seconds. Occasional gasps are not normal breathing and should be treated as a cardiac arrest emergency.
Call 911 immediately, or point to a specific bystander and give a direct instruction: “You in the blue shirt, call 911 and come back.” If other people are nearby, tell someone else to get the AED. In a workplace, school, fitness center, or other public facility, AEDs are often kept near main entrances, security desks, first aid stations, or clearly marked wall cabinets.
If you are alone with an adult, call 911 on speakerphone if possible, then begin CPR. Do not leave the person to search for an AED unless you know it is very close and you can retrieve it quickly.
Start CPR while the AED is being retrieved
Place the heel of one hand in the center of the chest, with your other hand on top. Keep your arms straight and push hard and fast at a rate of 100 to 120 compressions per minute. Allow the chest to rise fully after every compression.
For adults, compress at least 2 inches deep. If you are trained and willing to provide rescue breaths, give 30 compressions followed by two breaths. If you are not trained, not confident with breaths, or unable to give them, hands-only CPR is still a meaningful response. Keep compressions going until the AED is ready, another trained responder takes over, the person begins showing signs of life, or EMS directs you to stop.
High-quality CPR keeps blood moving to the brain and heart. The AED may correct a dangerous rhythm, but CPR remains essential before and after a shock.
How to use an AED step by step
As soon as the AED arrives, place it beside the person near their head or shoulder. Turn it on. Some units have a power button; others activate when you open the lid. From that point forward, listen carefully to the device. AEDs are made to guide rescuers through the process.
Expose and prepare the chest
Remove or cut away clothing so the person’s bare chest is visible. The chest needs to be dry enough for the adhesive pads to stick securely. If the person is wet from rain, a pool, or sweat, quickly dry the chest with a towel or shirt. You do not need to move them indoors if the scene is otherwise safe.
If there is excessive chest hair where the pads must be placed, it may prevent good pad contact. Many AED kits include a razor. Shave only the pad placement area if necessary, and do it quickly. Do not delay defibrillation for minor hair or sweat concerns.
Remove medication patches from the pad area using gloves or another barrier if available, then wipe the skin clean. If the person has a visible pacemaker or implanted defibrillator, usually seen as a small bump under the skin near the collarbone, place the pad at least 1 inch away from it. Do not place a pad directly over the device.
Place the pads exactly as shown
Open the pad package and look at the pictures printed on the pads. For most adults, place one pad on the upper right side of the bare chest, just below the collarbone. Place the second pad on the lower left side of the chest, below the armpit.
The illustrations on the AED pads are your best guide because models can vary. Press each pad firmly onto the skin, making sure there are no large air pockets. Plug the pad connector into the AED if the pads are not already connected.
For children, use pediatric pads or the AED’s pediatric setting if available. Follow the device instructions and the pad diagrams. If pediatric pads are unavailable, standard adult pads may be used for a child in a life-threatening emergency. For infants and small children, pads may need to be placed on the front and back so they do not touch each other.
Clear the person for analysis
Once the pads are attached, the AED will tell you to stop CPR while it analyzes the heart rhythm. Say clearly, “Everybody clear,” and visually confirm that no one is touching the person, the pads, or the clothing around the chest.
This pause matters. Movement can interfere with the AED’s analysis. Keep the interruption as short as possible, and do not touch the person until the AED tells you it is safe.
Deliver a shock only when the AED advises it
If the AED says, “Shock advised,” it will charge. Again, loudly state that everyone must stand clear. Look from head to toe to ensure no one is in contact with the person. Press the flashing shock button when instructed.
The person may have a brief muscle movement when the shock is delivered. That is expected. Do not check for a pulse or wait to see if they wake up. Immediately resume CPR, starting with chest compressions, unless the AED gives different instructions.
If the AED says, “No shock advised,” begin CPR immediately. A person can still be in cardiac arrest even when a shock is not advised. The AED will usually reanalyze the rhythm about every two minutes and will tell you when to pause.
AED safety concerns that should not stop you
People sometimes hesitate because they are worried about doing something wrong. AEDs have built-in safeguards, and the greater risk is delaying care. Still, a few precautions help you use the device safely.
Do not use an AED while anyone is touching the person. Keep oxygen sources away from the chest while a shock is delivered if oxygen is in use. Move the person away from standing water if practical, but do not waste critical time trying to create perfect conditions. Dry the chest and make sure rescuers are clear.
A person wearing jewelry, including a necklace or body piercing, can generally still be defibrillated. Avoid placing pads directly over metal if you can. A pregnant person can also receive AED treatment when they are in cardiac arrest. The priority is restoring circulation.
What happens after the AED is attached
Continue following every AED prompt until EMS professionals take over. Do not remove the pads, even if the person begins moving or breathing, unless emergency responders instruct you to do so. If the person starts breathing normally but remains unresponsive, place them on their side in a recovery position if you can do so safely, keep monitoring their breathing, and leave the pads attached.
If you are working with other bystanders, switch CPR providers about every two minutes when possible. Compression quality drops when rescuers get tired. Make the switch during the AED’s analysis period to reduce interruptions.
Afterward, provide responders with the details you know: when the person collapsed, whether anyone saw it happen, how long CPR was performed, and whether the AED delivered a shock. This information can support the next stage of care.
Confidence comes from hands-on practice
Reading the steps is useful, but a real emergency can feel very different from a written scenario. Hands-on CPR and AED training gives you the chance to practice pad placement, work through AED prompts, deliver effective compressions, and make decisions with an instructor beside you.
For employers, schools, and community organizations, training a team is one of the most practical ways to strengthen emergency readiness. An AED on the wall is valuable. People who know how to use it quickly and confidently make it far more effective.
East Coast Safety Consulting provides practical CPR, AED, First Aid, and BLS training built around the skills people need to respond when the moment is real. The goal is not to make an emergency feel easy. It is to help you recognize what matters, take the next right step, and stay with the person until help arrives.
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