How to Use an AED in an Emergency

Learning how to use an AED in an emergency can be one of the most valuable skills you ever acquire — because when every second counts, you may help save a life. In the U.S., sudden cardiac arrest (SCA) affects over 350,000 people outside of hospitals each year.

This article provides a clear, actionable, step-by-step guide to using an automated external defibrillator (AED): what it is, when to use it, how to operate one safely, what to do afterwards, and how to prepare ahead of time. The goal: to help you act confidently and effectively in a real‐life emergency.

Why Rapid Action Matters

When someone suffers sudden cardiac arrest, their heart’s electrical system malfunctions, and it stops pumping blood effectively. According to the American Heart Association (AHA), a person’s chance of survival drops by 7% to 10% for each minute that passes without restoring a heartbeat. Early CPR (cardiopulmonary resuscitation) and early defibrillation via AED are the two most important interventions for survival.

Here are some key statistics:

• Out-of-hospital cardiac arrest survival is very low — fewer than 10 % survive when no bystander AED is used.

• If an AED is used quickly, especially within the first few minutes, survival rates can double or triple compared to no AED.

• Yet, AEDs are used by bystanders in only a small fraction of cases — less than 5–10% of public location cardiac arrests see AED use before EMS arrival.

Bottom line: Being prepared to use an AED reduces delay, increases survival chances — and you can make that difference.

What an AED Is and How It Works

An AED (automated external defibrillator) is a portable, lightweight device designed for use by lay responders (non-medical personnel) to deliver a lifesaving electric shock when someone is in cardiac arrest.

Here’s a breakdown of how it works:

1. Recognition: You identify someone unresponsive, not breathing normally, or has collapsed.

2. Connection: You attach the AED’s electrode pads to the person’s bare chest.

3. Analysis: The AED uses sensors to detect the heart rhythm and determine whether a shock is indicated.

4. Shock Delivery: If rhythm is “shockable,” the AED guides you to ensure no one is touching the person, and then delivers a shock.

5. Post-shock Care: After the shock (or if no shock is advised), the AED prompts you to continue CPR.

Because most AEDs include voice prompts, visual instructions, and simple diagrams, they are designed for use by the public—with minimal training.

Step-by-Step: How to Use an AED in an Emergency

Here’s a practicum you can follow in a real emergency. Keep in mind: every situation is unique, so adapt as needed, but this serves as a reliable framework.

1. Assess the situation and call for help

• Immediately check if the person is unresponsive (no response to your shout, touch) and not breathing normally.

• Shout for help; send someone to call 911 (in the U.S.) — or if you’re alone, call first before beginning aid if you must leave the person to call.

• Ask someone to fetch the nearest AED while you begin CPR without delay (if you know CPR) or start basic help. According to the AHA: call → CPR → AED.

2. Begin high-quality CPR

• With the person lying flat on a firm surface, kneel beside them.

• Place the heel of one hand at the center of the chest (lower half of the sternum) and the other hand on top. Keep elbows straight and shoulders over hands.

• Push hard and fast: at least 2 inches (5 cm) deep for adults, at a rate of 100-120 compressions per minute. Let the chest fully recoil between compressions.

• After every 30 compressions, give 2 rescue breaths (if trained and comfortable) or continue hands-only CPR if not trained.

• Continue until the AED is ready or you must stop (e.g., scene becomes unsafe or professional help arrives).

3. Turn on the AED and follow voice prompts

• Once the AED arrives, open the case and power the device by pressing its “On” or “Power” button (or by lifting the lid in some models).

• The AED will guide you via voice and visual commands: “Attach pads,” “Analyzing rhythm,” “Shock advised / no shock advised,” etc.

4. Prepare the person for pad placement

• Expose the person’s chest. Remove or cut clothing as needed. If the chest is wet (e.g., sweating or in the rain), dry it quickly with a towel or cloth.

• If chest hair is excessive and pads may not stick, quickly shave or use the razor from the AED kit (if available) so adhesive pads adhere well.

5. Place the AED pads correctly

• Remove the protective backing from the pads.

• Apply one pad to the upper right chest (just below the collarbone) and the other pad to the lower left side of the chest (below the armpit). Follow the picture on the pad.

• Make sure no one is touching the person once the pads are connected and before the AED analyzes.

6. Let the AED analyze and then act

• The AED will automatically analyze the heart rhythm. Make sure nobody is touching the person during analysis.

• If the AED indicates “Shock advised,” ensure everyone is clear, then press the shock button if required (some devices deliver automatically).

• After shock delivery (or if “No shock advised”), the AED will instruct you to resume CPR. Follow its prompts.

7. Continue CPR and follow AED guidance until help arrives

• After the shock (or no shock), resume CPR immediately—starting with chest compressions.

• The AED may re-analyze every 2 minutes or at intervals; follow its cues.

• Do not remove pads unless EMS/paramedics say to.

• Continue until: (a) trained EMS personnel take over; (b) you’re too exhausted to continue safely; or (c) the person shows signs of life (breathes normally, moves, etc).

8. After the person recovers or EMS takes over

• If the person regains consciousness or starts breathing normally, place them in the recovery position (lying on their side) and keep monitoring until help arrives.

• Ensure EMS takes away the AED pads and your incident information (what you did, times, etc) for their report and device reuse.

• Report the incident to your organization (if in a workplace) so the AED pads/battery can be restocked and the unit is ready for next use.

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Special Considerations and Practical Tips

A. Location and preparation of AEDs in public spaces

• AEDs should be placed where they are visible and accessible within 3–5 minutes from any point in the area. Delays beyond 5 minutes drastically reduce survival.

• Common placement: near elevators, lobbies, gyms, school corridors, and large workplaces.

• Even if you’ve never seen one in your building, ask your facility manager: knowing its exact location speeds your action.

B. Who can use an AED?

• AEDs are designed for lay rescuers; you do not need to be a healthcare professional.

• Children and teens can use AEDs safely: there is no minimum age to operate one.

• For pediatric victims: Devices may have child-specific pads/attenuators for children ages 1-8; for ages 8+, use adult pads.

C. Myths and fears — and why you shouldn’t hesitate

• Fear of “doing it wrong” is common — but if someone is in cardiac arrest, you cannot make it worse by attaching an AED.

• Concern about legal liability: Many states’ Good Samaritan laws protect bystanders who act in good faith.

• Some people wait for EMS instead of acting — delaying response reduces survival drastically. Aim to start AED + CPR before EMS arrives if at all possible.

D. Maintenance, readiness, and training

• Even if you’re not purchasing an AED yourself, it’s good to know if your building has one, who is trained to use it, and where the spare pads/batteries are kept.

• Organizations should register AEDs with local EMS dispatch so 911 dispatchers know devices exist onsite.

• Training in CPR + AED use increases confidence, coordination, and speed — formal courses (like the AHA Heartsaver® CPR AED) are available.

• For AED program managers: there is a checklist of 10 important steps to maintain the program (placement, training, maintenance, oversight, etc).

Mistakes to Avoid and How to Improve Your Response

• Delay in calling 911: Don’t wait — have someone call while CPR begins.

• Inadequate CPR quality: Too shallow or slow compressions reduce effectiveness; aim for full recoil and correct rate.

• Wasting time looking for an AED: If it’s not easily accessible, continue CPR until one arrives rather than wasting minutes.

• Incorrect pad placement: Ensure correct placement; is chest hair, moisture, or metal interfering? Fix quickly.

• Ignoring AED prompts: Once turned on, follow every voice/visual instruction; don’t improvise.

• Assuming only professionals can use it: Lay rescuers are absolutely empowered and expected to use AEDs; don’t hold back.

FAQs — Your Key Questions Answered

Q: When exactly should I use an AED?

Use an AED when you find an unresponsive person who is not breathing normally or only gasping, and you suspect sudden cardiac arrest. Once the person has no pulse or no effective breathing, it’s time. If unsure, begin CPR and get the AED anyway—early is better.

Q: What if I don’t know how to use an AED?

You don’t need to be an expert. Most AEDs will talk you through each step with voice prompts and visuals. Just turn it on and follow instructions — while you continue CPR. Training helps, but a lack of training should not prevent you from using one.

Q: Does someone need a specific model? What kind of AED should we buy for our workplace?

The AHA does not recommend one brand/model over another. Key features: simplicity, voice prompts, ease of pad application, clarity of instructions. When placing devices, plan for accessibility (3-5 minute reach) and maintenance.

Q: Is it safe to use an AED on children?

Yes — lay responders may use an AED on children. Some devices offer pediatric pads for children ages 1-8; for children 8 and older, adult pads are used.

Q: Will I get in trouble if something goes wrong?

Under Good Samaritan laws present in most states, bystanders acting in good faith to assist in an emergency are typically protected from liability. The AHA emphasizes you can’t make it worse by using an AED when the person is in cardiac arrest.

Q: What should you NOT do when using an AED?

• Don’t ignore CPR while retrieving the AED.

• Don’t proceed if the chest is very wet and you haven’t taken time to dry it.

• Don’t touch the person while the AED is analyzing or delivering a shock.

• Don’t stop CPR unless the person recovers, EMS arrives, or you can’t continue.

• Don’t delay calling 911 or letting others know help is on the way.

Read Also: What NFPA Standard Specifically Covers Safety in the Workplace?

Be Ready: Pre-Emergency Checklist

Here’s a quick checklist you can run through (in your home, workplace, or public venue) to boost readiness:

• Locate nearest AED(s): Know where they are and how long it takes to retrieve.

• Ensure signage: AEDs should be clearly marked and accessible.

• Confirm maintenance: Pads not expired, device self-tests passed, batteries in place.

• Register AED with local EMS dispatch (if required by your state).

• Ensure that at least some people in the environment are trained in CPR + AED use.

• Practice scenario mentally: when the alarm rings, we call 911, we start CPR, and we send someone for an AED.

• Keep a record of usage, maintenance, and training for audit and readiness.

Conclusion

Knowing how to use an AED in an emergency isn’t just about reading instructions — it’s about being mentally and practically prepared to act. When a person’s heart has stopped, time is the enemy. Your rapid response — call 911, begin CPR, deploy the AED — literally becomes their best chance to survive.

By understanding what an AED is, how it works, following the step-by-step process above, preparing ahead of time, and overcoming hesitation, you give yourself the confidence to act when it matters most. Remember: survival depends not just on devices, but on people willing to step in.