An Automated External Defibrillator (AED) is one of the most powerful lifesaving tools available during a sudden cardiac arrest (SCA). When used quickly and correctly along with CPR, an AED can dramatically increase a person’s chance of survival. Yet many bystanders hesitate to use an AED because they are unsure how it works.
The truth is simple: AEDs are designed for everyday people, not just medical professionals. This guide explains how to use an AED step by step, when to use it, and how it works alongside CPR to save lives.
What Is an AED and Why Is It Important?
An AED (Automated External Defibrillator) is a portable medical device that analyzes heart rhythm and delivers an electric shock if needed to restore a normal heartbeat.
Sudden cardiac arrest can happen anytime, anywhere, and survival depends on how fast CPR and defibrillation begin. According to cardiac survival data, each minute without defibrillation reduces survival by 7–10%.
Learn more in What Is an AED and How It Works.
When Should You Use an AED?
You should use an AED as soon as possible when a person:
- Is unresponsive
- Is not breathing normally (or only gasping)
- Has no signs of circulation
If an AED is available, use it immediately, even before emergency responders arrive.
Important: You cannot accidentally harm someone with an AED. If a shock is not needed, the AED will not deliver one.
How to Use an AED: Step-by-Step Instructions
If you encounter someone who has collapsed and is unresponsive, follow these steps immediately:
Step 1: Ensure Scene Safety
Before helping, make sure the area is safe for you and the victim. Avoid water, traffic, or electrical hazards.
Step 2: Check Responsiveness and Breathing
- Tap the person and shout.
- Look for normal breathing for no more than 10 seconds.
If there is no response and no normal breathing, call for help.
Step 3: Call 911 and Get the AED
- Ask someone to call 911.
- Ask another person to retrieve an AED immediately.
If you are alone, call 911 yourself and get the AED if nearby.
Step 4: Start CPR Until the AED Arrives
Begin high-quality CPR:
- Push hard and fast in the center of the chest
- Rate: 100–120 compressions per minute
- Depth: At least 2 inches for adults
👉 Read: How to Perform Adult CPR?
Step 5: Turn On the AED
Once the AED arrives:
- Turn it on (press the power button or open the lid)
- The device will begin clear voice instructions
Step 6: Expose the Chest and Attach AED Pads
- Remove clothing from the chest
- Dry the chest if wet
- Shave excessive chest hair if needed (most AED kits include a razor)
Place the pads:
- One pad on the upper right chest
- One pad on the lower left side below the armpit
For children or infants, use pediatric AED pads if available.
👉 Link to Child & Baby CPR Guidelines.
Step 7: Let the AED Analyze the Heart Rhythm
- Make sure no one is touching the person
- Loudly say, “Clear!”
- The AED will automatically analyze the heart rhythm
Step 8: Deliver the Shock If Advised
If the AED says “Shock advised”:
- Ensure everyone is clear
- Press the shock button (if required)
Some AEDs deliver shocks automatically.
Step 9: Resume CPR Immediately
After the shock:
- Start CPR right away
- Continue until the AED tells you to stop or help arrives
The AED will reanalyze every 2 minutes.
Special Considerations for AED Use
While AEDs are designed to be foolproof, a few scenarios require slight adjustments:
- Children and Infants: Use pediatric pads if available. If not, use adult pads, but place one in the center of the chest and the other on the center of the back to ensure they do not touch.
- Water: If the person is in a puddle or submerged, move them to a dry area. The chest must be dry before applying pads.
- Pacemakers: If you see a small lump or scar on the chest, avoid placing the pad directly over it. Move the pad an inch or two away.
- Medicine Patches: Remove any nicotine or medication patches with a gloved hand and wipe the area clean before applying the AED pad.
Can Anyone Use an AED?
Yes. AEDs are:
- Safe
- Fully automated
- Designed for untrained users
Good Samaritan laws in the U.S. protect bystanders who act in good faith during emergencies.
Common AED Mistakes to Avoid
- Waiting too long to use the AED
- Not resuming CPR after a shock
- Touching the victim during rhythm analysis
- Placing pads incorrectly
- Fear of “doing it wrong”
Remember: Doing something is always better than doing nothing.
Final Thoughts: Every Second Counts
Knowing how to use an AED can turn an ordinary bystander into a lifesaver. Sudden cardiac arrest survival depends on fast action, early CPR, and prompt defibrillation.
Take the time to learn, practice, and get CPR certified because the life you save may be someone you love.
Frequently Asked Questions (FAQs)
How do you use an AED for the first time?
Turn it on, follow voice prompts, attach pads to the bare chest, and deliver a shock if advised. The AED guides you through every step.
Can you use an AED without CPR training?
Yes. AEDs are designed for untrained users. However, CPR training significantly improves survival outcomes.
Will an AED shock someone who doesn’t need it?
No. An AED only delivers a shock if a dangerous heart rhythm is detected.
Is it safe to use an AED on a child or baby?
Yes. Use pediatric pads if available. If not, adult pads can be used in an emergency following placement guidelines.
Should you stop CPR to use an AED?
Only briefly. Stop CPR when the AED is analyzing or delivering a shock, then resume immediately.
Where are AEDs usually located?
AEDs are commonly found in public places such as airports, schools, offices, gyms, and shopping centers.