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When To and When Not to Use an AED: Do’s and Dont’s of Using a Defibrillator

When Not to Use a Defibrillator: Do’s and Don’ts of Using an AED

Knowing when not to use a defibrillator is just as important as knowing how to use an AED, and where to find one. Here’s why.

Automated External Defibrillators (AEDs) save over 1,700 lives in the United States every year. However, many Americans do not currently know where to locate AEDs or how to use them. At Avive, we see room for improvement to save thousands more lives annually. 

AEDs are medical devices that send electric pulses to a person’s heart, restoring a normal heart beat. AEDs are the only way to restore a normal heartbeat when someone is experiencing Sudden Cardiac Arrest (SCA).

Knowing where to find and how to use an AED is vitally important. But some patients with irregular heartbeats, or in certain circumstances, should never be treated with an AED. Knowing when to use an AED and when not to use one is an equally essential skill in saving a life.

When to Use an AED (Defibrillator)

You should only use an AED on a person if:

  • their heart suddenly stops beating
  • they are experiencing Sudden Cardiac Arrest (SCA). Symptoms are immediate and drastic and include:
  • No breathing, or gasping noises paired with abnormal breathing
  • Unresponsive
  • Unconscious
  • No pulse

If you encounter someone with these symptoms, call 911, designate someone to search for a defibrillator, and immediately begin CPR. It is important to acknowledge that over 80% of SCAs cases occur in the home, which underscores the importance of having an emergency action plan in place.

When NOT to Use an AED (Defibrillator)

There are various special circumstances that require extra care when determining if and how to use an AED. All AED units have their own intended use statements, so we recommend all AED owners review their unit’s requirements.

The Victim Is Conscious & Breathing Normally

If the person is conscious and breathing normally, they do not require an AED shock. 

Generally speaking, an AED should be used when a person is unconscious (not responsive) and not breathing properly. It is important to know that sometimes victims of Sudden Cardiac Arrest in this state may demonstrate agonal breathing for seconds to minutes after their heart has stopped beating. Agonal breathing is NOT normal breathing. It is crucial that you do not mistake agonal breathing for real breathing. Agonal respirations can sound like gasping, snorting, strange, shallow half-breaths, or possibly moaning. A person experiencing agonal breathing may also show signs of twitching muscles. When a person is not responsive and breathing agonally, an AED should be used.

The Victim Has a DNR

If you notice a bracelet or a tattoo on the victim’s chest, wrist or forearm saying, “Do Not Resuscitate” or “DNR”, do not use an AED on them. The DNR order indicates that the person does not want resuscitation. It is best that you respect their wishes.

Faulty AED Parts

If your AED has faulty parts it may not be functional. If you’re stuck with a non-functional AED during an emergency, search for another one nearby.

When Special AED Use Circumstances Might Apply

The Patient Has a Pacemaker or Medication Patch

While pacemakers are designed to handle shocks from an AED, you should not  use a defibrillator over the skin where surgeons installed the pacemaker.

A pacemaker can usually be seen or palpated under the skin, in the upper part of the person’s chest. Ensure you follow any instructions for responding to victims with a pacemaker found in your AED’s user manual and place the AED pads where indicated.

Do not place AED pads over medical patches. Remove them first.

Cardiac Patient with Pacemaker

The Person Is Wet or Lying on a Wet Surface

SCA can happen at any time, including when a person is in or near a body of water, or in the rain or snow. In wet conditions, AEDs can be dangerous to use, causing harm to the victim or the person providing the care. Since AEDs deliver an electrical shock, you must take specific care when treating the cardiac arrest victim.

Never use an AED while submerged in water. Always move someone submerged in water to dry land before delivering an AED shock. You cannot apply the AED pads, which deliver the necessary electrical shock to the victim’s chest, until the shirt has been removed and the skin dried thoroughly. Once the person’s skin is dry, power on the AED and follow its instructions the same way you would during a normal response.

When Not to Use a Defibrillator: Do’s and Don’ts of Using an AED

The Victim Has a Hairy Chest

AED pads need direct contact with the patient’s skin in order to work properly. If the person has a very hairy chest, it may be necessary to remove some hair so the electrode pads will adhere properly to the person’s skin. Many defibrillator kits include a razor to quickly shave the victim’s chest. If you cannot find a razor, apply pressure to place the pads as close to their chest as you can.

The Person Is Suffering From Heart Attack

The main difference between Sudden Cardiac Arrest and heart attack is the underlying problem that occurs in the heart. 

  • Cardiac arrest is an electrical problem where a malfunction in the heart’s electrical system causes it to stop beating. Normally, the heart is controlled by regular electrical impulses that make it beat. When Sudden Cardiac Arrest happens, these electrical impulses become scrambled and the heart can no longer pump blood (containing oxygen that is necessary for life) around the body. 
  • By contrast, a heart attack is when the blood supply to the heart is cut off due to a blockage in an artery. This blockage causes damage to the heart and the muscle begins to die. 

If the patient is having a heart attack they will be breathing and conscious, in these cases an AED is not needed to restart the heart. Victims of cardiac arrest, however, will suddenly become unconscious and collapse. They will be unresponsive and not breathing or breathing agonally (abnormally). Unlike cardiac arrest, which always happens suddenly, a heart attack can be sudden or may develop over time. 

Learn more about the signs and symptoms of a heart attack.

If someone is experiencing a heart attack, immediately call 911.

Safety Considerations for AED Users – Using an AED on Infants and Children

AED pads come in multiple sizes, infant and adult. Ensure you use the appropriate pads for the size (age or weight) of the victim. Your AED’s user manual will disclose when to use adult pads and when to use child pads, as well as any other special circumstances that might exist.

Learn more about how to resuscitate infants and children.

When using an AED on someone suffering from SCA, keep the following in mind:

  • Avoid areas with a buildup of flammable vapors. Sparks from the AED could cause a fire.
  • Do not touch the patient with any part of your body while the AED is delivering a shock. Clear the area around the victim and prevent anyone else from touching the patient. 
  • Do not use an AED while riding in a moving vehicle.

Always check your AED manufacturer’s user manual for specific safety and operational and maintenance instructions pertaining to your AED unit.

Time is of the Essence

During cardiac arrest, a person’s chances of survival drop by 10% per minute, so it is critical that you quickly decide when to use an AED and determine where it is located.

Here are a few critical questions that you must ask yourself in order to make a quick decision:

  • Is the AED operational?
  • Does the situation call for the use of an AED?
  • Does the person suffering from Sudden Cardiac Arrest require any special care (such as having a pacemaker, being a young child or infant, or having a hairy chest)?
  • Does the scenario have any special circumstances (such as a wet or unsafe location, or faulty AED parts)?

*All information on the Avive website is provided in good faith. However, Avive makes no representation or warranty of any kind, express or implied, regarding the accuracy, validity, or completeness of any information on the Site. Any medical/health information on the Site is for general informational and educational purposes only and is not a substitute for professional medical/health advice.


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