Emergency advice

Cardiac arrest:

  1. Call 999.
  2. Start CPR immediately.
  3. Attach and follow the defibrillator voice prompts while continuing CPR. 

What is a cardiac arrest?

A cardiac arrest happens when someone’s heart stops.

If someone has become unresponsive and they are not breathing normally, they could be in cardiac arrest and you need to act quickly. Call 999 or 112 for emergency help and start CPR, using a defibrillator if available.

Signs and symptoms

If someone has a cardiac arrest, they may:

  • be unresponsive
  • be not breathing normally
  • show no movement or signs of life. 

What to do

  1. First aid - call 999 or 112 for emergency help

    If you find someone collapsed, you should first perform a primary survey. If this shows that they are unresponsive and not breathing, shout for help. Ask a helper to call 999 or 112 for emergency help while you start CPR. Ask a helper to find and bring a defibrillator, if available.

    • If you are on your own, use the hands-free speaker on a phone so you can start CPR while speaking to ambulance control.
    • Do not leave the casualty to look for a defibrillator yourself, the ambulance will bring one.
  2. Cardiac arrest first aid - start CPR

    Start CPR.

    Kneel by the casualty and put the heel of your hand in the middle of their chest.

    Put your other hand on top of the first.

    Interlock your fingers making sure they don't touch the ribs.

    Keep your arms straight and lean over the casualty.

    Press down hard, to a depth of about 5-6cm before releasing the pressure, allowing the chest to come back up.

  3. Cardiac arrest first aid - repeat compressions 30 times

    Repeat the compressions 30 times; at a rate of 100-120 compressions per minute.

    • The beat of the song ‘staying alive’ can help you keep the right rate.
  4. Cardiac arrest first aid - give two rescue breaths

    After 30 compressions, you need to give two rescue breaths. 

    To do this, open the airway by placing one hand on their forehead to tilt the head back and use two fingers from the other hand to lift the chin.

  5. Cardiac arrest first aid - blow into their mouth for one second, until the chest rises

    Take the hand from the forehead and pinch the soft part of the nose closed. Allow the mouth to fall open. With the head still tilted, take a breath in and place your mouth over the casualty’s, forming a seal. Blow into their mouth for one second, until the chest rises. Take your mouth away and watch the chest fall.

    • If the chest doesn’t rise, check the airway is open - repeat step 4.
    • If you are not trained or do not feel comfortable performing rescue breaths, give continuous chest compressions.
  6. Cardiac arrest first aid - repeat compressions 30 times

    Continue to perform CPR, alternating 30 chest compressions with 2 rescue breaths, until either:  

    • emergency help arrives and takes over.  
    • the person starts showing signs of life and starts to breathe normally.
    • you are too exhausted to continue - if there is a helper, you can change over every one-to-two minutes with minimal interruptions to chest compressions.
    • a defibrillator is ready to be used.
  7. When the helper returns with a defibrillator, ask them to switch it on and take the pads out while you continue with CPR. They should remove or cut through clothing to get to the casualty's bare chest. They also need to wipe away any sweat.

    • The defibrillator will give voice prompts on what to do.
  8. Cardiac arrest first aid - apply the pads

    They should attach the pads to the casualty’s chest by removing the backing paper. Applying the pads in the positions shown.

    • The first pad should be on the upper right side below the collar bone.
    • The second pad should be on the casualty’s left side below the arm pit.
  9. Cardiac arrest first aid - follow the visual and verbal prompts from the defibrillator

    The defibrillator will analyse the heart's rhythm. Stop CPR, and make sure no one is touching the casualty. It will then give a series of visual and verbal prompts that should be followed.

    • If the defibrillator tells you that a shock is needed, tell people to stand back. The defibrillator will tell you when to press the shock button. After the shock has been given, the defibrillator will tell you to continue CPR for two minutes before it re-analyses.
    • If the defibrillator tells you that no shock is needed, continue CPR for two minutes before the defibrillator re-analyses.
  10. Cardiac arrest first aid - if casualty becomes responsive, put them in the recovery position

    If the casualty shows signs of becoming responsive such as coughing, opening their eyes, speaking, or starts to breathe normally, put them in the recovery position.

    Leave the defibrillator attached. Monitor their level of response and prepare to give CPR again if necessary.

Did you find this information helpful?

Related first aid advice

How to do the primary survey

Use the primary survey to quickly assess the situation and check the casualty for injuries or conditions that could be immediately life threatening. Find out what to do.

How to do CPR on an adult

If an adult is unresponsive and not breathing normally, you need to call 999 or 112 for emergency help and start CPR straight away. Learn what to do.

How to use a defibrillator

By using a defibrillator before an ambulance arrives, you can significantly increase someone’s chance of survival. Learn what to do.

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