If someone is unresponsive and not breathing normally—or is only gasping—call 911 (or your local emergency number), send someone for an automated external defibrillator (AED), and start CPR. When the AED arrives, switch it on and follow its spoken instructions. Keep everyone clear while it analyzes or delivers a shock, then resume CPR immediately.
What to do before the AED arrives
- Check the scene. Make sure it is safe to approach. Check whether the person responds and is breathing normally. Gasping is not normal breathing.
- Call emergency services. Call 911 in the United States, or your local emergency number elsewhere. Ask someone nearby to bring an AED. If you are alone, call and follow the dispatcher’s instructions.
- Start CPR. Begin CPR if the person is unresponsive and not breathing normally or is only gasping. Do not wait for the AED. If another person is available, have them continue CPR while you prepare the device. See the American Heart Association’s cardiac-arrest guidance for CPR details.
How to use the AED
- Turn it on. Follow the voice prompts. Some devices switch on when you open the lid; controls and prompts vary by model.
- Expose and prepare the chest. Remove clothing covering the chest or pad locations. If the chest is wet, wipe it dry so the pads can adhere to bare skin.
- Attach the pads as shown. Use the pictures on the pads, not a guess about placement. For the adult placement described by the American Red Cross, place one pad on the upper right chest and the other on the lower left chest, a few inches below the armpit. If the pads may touch, the Red Cross describes placing one in the middle of the chest and the other on the back between the shoulder blades.
- Connect the cable if needed. Some AEDs require you to plug the pad cable into the device; others do not. Follow the device prompts.
- Clear the person for analysis. Make sure nobody is touching them while the AED checks the heart rhythm. Say “clear” loudly and look around to confirm that rescuers and bystanders have stepped away.
- Give a shock only if directed. If the AED advises a shock, make sure everyone is clear. Press the shock button if the device tells you to. Some models deliver the shock automatically after warning everyone; follow that model’s prompts and keep clear.
- Resume CPR immediately. Restart CPR after a shock or a no-shock instruction. Follow any further AED prompts.
Keep going until help takes over
Continue CPR and follow the AED’s instructions until the person starts to move or breathe normally, emergency personnel take over, or the AED directs another action. Keep emergency dispatch involved even when an AED is available.
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Important limits and safety points
- An AED analyzes the heart rhythm and advises whether a shock is needed; it will not recommend a shock for every collapse. A no-shock instruction is a cue to resume CPR, not to stop helping.
- Keep hands off the person during rhythm analysis and shock delivery. Check that rescuers, bystanders, and the person are clear before a shock.
- Follow the pad illustrations and the device’s voice prompts. The Red Cross’s cited adult steps also cover a non-breathing child aged 8 or older who weighs more than 55 pounds. They do not establish pad placement or procedure for infants or smaller children; follow the AED and dispatcher instructions in those situations.
- Training is recommended by the FDA and Red Cross, but a public AED is designed to guide a lay rescuer. A course is useful preparation, not a prerequisite to helping. The Red Cross CPR course page provides training information.
What kind of public AED might you find?
Some AEDs are semi-automated: the rescuer presses the shock button when prompted. Fully automated models deliver the shock after warning people to stand clear. In either case, follow the prompts rather than trying to identify the model or operate it from memory. The FDA explains public-access and professional-use AEDs, operation types, and device accessories in its AED overview.
Why immediate action matters
More than 350,000 U.S. adults experience out-of-hospital cardiac arrest each year, according to the American Heart Association’s article published September 8, 2026. That article reports that bystanders administer CPR about 40% of the time and that about 1 in 8 people with cardiac arrest in a public setting receive a shock from a bystander using an AED. These figures describe the AHA’s reported U.S. context, not an individual person’s odds. The practical priority is to call for help, start CPR, and use the AED as soon as it is available.
Quick Recap
Rank #4
- Philips HeartStart M5066A-R01 OnSite AED Defibrillator is a virtually ready to use emergency medical device for cases of suspected sudden cardiac arrest
- A portable heart defibrillator in a convenient carry case with pre-installed spare pads and cartridge; provides real-time CPR instructions and step-by-step voice prompts
- Suitable for emergency use in all public environments including restaurants, offices, gyms, and airports and businesses of any size.
- Training not required for use. Device provides simple, intuitive instructions for people who have never used a defibrillator
- Philips defibrillators perform a daily, weekly and monthly self-test to eliminate the need for manual calibration. May be converted to an AED trainer with the use of Adult or Infant/Child Training Pads Cartridge (sold separately)
Rank #3
- 𝗦𝗘𝗖𝗨𝗥𝗘 𝗗𝗨𝗔𝗟 𝗦𝗧𝗢𝗥𝗔𝗚𝗘: Secure both your AED & First Aid Kit in this wall mount compatible storage with reinforced door. Durable, visible, & accessible ensuring quick access during emergencies.
- 𝗛𝗜𝗚𝗛-𝗩𝗜𝗦𝗜𝗕𝗜𝗟𝗜𝗧𝗬 𝗦𝗜𝗚𝗡𝗔𝗚𝗘: Includes 'AED' & 'First Aid' sign for visibile identification. Ensure first responders and/or bystanders can quickly locate emergency supplies in any setting.
- 𝗨𝗡𝗜𝗩𝗘𝗥𝗦𝗔𝗟 𝗪𝗔𝗟𝗟 𝗠𝗢𝗨𝗡𝗧 𝗖𝗢𝗠𝗣𝗔𝗧𝗜𝗕𝗟𝗘: Easily installs on any wall for visibility & convenience. For use in homes, offices, gyms, schools, warehouses, & public spaces. Holds AED kits up to 13″W x 12″H x 7″D.
- 𝗛𝗘𝗔𝗩𝗬 𝗗𝗨𝗧𝗬 𝗦𝗧𝗘𝗘𝗟 𝗖𝗢𝗡𝗦𝗧𝗥𝗨𝗖𝗧𝗜𝗢𝗡: Reinforced with 22 gauge, powder-coated, corrosion-resistant steel for long-lasting durability in high-traffic spaces. Features clear acrylic window to ensure contents are visible.
- 𝗢𝗣𝗧𝗜𝗢𝗡𝗔𝗟 𝗕𝗔𝗧𝗧𝗘𝗥𝗬 𝗢𝗣𝗘𝗥𝗔𝗧𝗘𝗗 𝗔𝗟𝗔𝗥𝗠: Sounds when door is opened to alert responders and authorities in the area. Can be armed or disarmed with keyed switch, making it versatile for any environment. Two keys included.
Rank #2
- Philips HeartStart Home and OnSite AED Defibrillator Long Life Replacement Battery, a back-up power source for your Philips HeartStart FRx, OnSite or Home defibrillator
- A high-quality, disposable, lithium manganese dioxide battery with a five-year shelf life (four-year lifespan once installed)
- Make sure your Philips device is always ready by having a spare or replacement battery to hand
- What’s in the box: 1 Philips HeartStart Long Life LiMN02 Replacement Battery
- Please contact Philips directly with any questions regarding the performance or operation of your HeartStart products. Replacements are permitted for warranty purposes only
#1 Best Overall
- Included Components: Heartstart Onsite Aed Defibrillator, Battery, Adult Smart Pads Cartridge, Setup
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