• Adult Cardiac Arrest

    What is Cardiac Arrest?

    Cardiac arrest occurs when the heart stops beating or beats too ineffectively to circulate blood to the brain and other vital organs. The electrical impulses that normally coordinate the heart muscle’s contraction and beating become abnormal and chaotic. This causes the heart to lose the ability to beat rhythmically, or to stop beating altogether.

    Cardiac arrest can happen suddenly and without any warning signs. When this occurs, the person is said to have experienced sudden cardiac arrest. People who have a history of cardiovascular disease or a congenital heart disorder are at higher risk for sudden cardiac arrest. However, sudden cardiac arrest can happen in people who appear healthy and have no known heart disease or other risk factors for the condition. A person who experiences sudden cardiac arrest is at very high risk for dying and needs immediate care.

    Emergency Steps


    Check the scene safety, form an initial impression, obtain consent and put on PPE, as appropriate.

    If person appears unresponsive, check for responsiveness.


    Check for signs and symptoms.

    • Not responsive*
    • Not breathing, or only gasping*

    Note: Signs and symptoms with a * require immediate emergency medical treatment.


    Call 9-1-1 and get equipment, including an AED if available.


    Give Care.

    Cardiac Arrest – Adult – FAQs

    Why is it important to start CPR right away for a person experiencing cardiac arrest?

    Every second counts in cardiac arrest. Recognizing cardiac arrest and activating the EMS system, immediately beginning CPR, and using an AED as soon as possible gives the person the best chance for surviving the incident.

    Won’t I break the person’s ribs?

    You might, but don't worry about this. Remember your priority is to keep the blood circulating. A damaged rib will mend, but without delivering chest compressions, the person’s chances of survival are significantly reduced.

    What if I do chest compressions, but the person is still breathing?

    Accidently performing chest compressions on an unresponsive person who is breathing will not create life-threatening injuries. The danger of not providing chest compressions to a person in cardiac arrest clearly outweighs any potential risks.

    How long should I do compressions for?

    You should keep going until:

    • The person shows an obvious sign of life.
    • The scene becomes unsafe.
    • An AED is ready.
    • You’re too exhausted to continue.
    • Another trained responder takes over.
    • EMS arrives and begins care.

    If there is someone else who can help, change every 1 to 2 minutes, with minimum interruption to chest compressions.

    Will I restart the heart if I give chest compressions?

    Chest compressions pump a small amount of blood around the body to keep the organs—most importantly the brain—alive. You may not see any visible change in the person's condition, but don't give up. Chest compressions significantly increase the possibility of the person being successfully resuscitated when EMS arrives and continues care. The chance of restarting the heart by chest compressions alone is very low. To restart, a heart usually needs an electric shock from a defibrillator.

    Can I use a defibrillator?

    Yes, you can use an automated external defibrillator (AED) even if not trained. When you turn on the AED, it will prompt you about the steps to take. Many public places, such as train stations and shopping centers, now have them available.

    What if the breaths do not make the chest rise?

    If the first breath does not cause the chest to rise, re-tilt the head and ensure a proper seal before giving the second breath.

    If the second breath does not make the chest rise when beginning CPR, an object may be blocking the person’s airway.

    • Immediately begin chest compressions. The chest compressions used in CPR may dislodge the object.
    • Before attempting breaths again, open the mouth and look for an object in the person’s mouth.
    • If you see it, remove it with a finger sweep using your index finger.
    • Never do a finger sweep if you don’t see an object because you might push the object further into the person’s airway.

    Should I give CPR and use an AED on someone having a heart attack?

    A heart attack is different from a cardiac arrest. With cardiac arrest, the heart has stopped or is not pumping blood. With a heart attack, the heart may not be working normally, but it is still pumping blood. An AED should only be used on a person who is unresponsive and not breathing (cardiac arrest).

    Does it matter where I place each of the AED pads?

    It is best to place pads as indicated. But if pad placement is reversed, the AED will still work.

    In general, for an adult, place one pad on the upper right side of the chest and the other pad on the lower left side of the chest a few inches below the left armpit. If the pads touch, position one pad in the middle of the chest and the other pad on the back between the shoulder blades.

    Is it safe to use an AED in a pool or when the person is lying in a puddle of water? What about a metal surface?

    If the person is in water, remove them from it before using the AED. However, it is safe to use an AED in rain or snow. It is safe to deliver a shock to a person in cardiac arrest on a metal surface as long as appropriate safety precautions are taken.

    • Avoid allowing the defibrillation electrodes to contact the metal surface.
    • Ensure that no one is touching the person when the shock button is pushed.

    Is it safe to use an AED on a person who has an implantable cardioverter-defibrillator (ICD) or pacemaker device?

    It is safe to use an AED on a person with an ICD or pacemaker device. However, do not place the AED pads directly over the device if you can see it or know the person has one. Doing so may interfere with the delivery of the best shock. Adjust AED pad placement if necessary.

    Do I need to remove things like a bra, hair, jewelry or body piercings before using an AED?

    It is best to remove a bra first, but if you can’t, make sure the AED pads are completely touching skin. Chest hair rarely interferes with pad adhesion. In most cases, it is unnecessary to shave the chest. Do not delay the use of an AED to remove jewelry or body piercings. However, avoid placing the AED pads directly over metallic jewelry or body piercings.

    Is it safe to use an AED on a pregnant woman?

    An AED is safe to use on a pregnant woman and offers the best chance of survival for both the mother and offers the best chance of survival for both the member and the fetus.

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