A cardiac arrest is when your heart suddenly stops pumping blood around your body. When your heart stops pumping blood, your brain is starved of oxygen. This causes you to fall unconscious and stop breathing.
A cardiac arrest usually happens without warning. If someone is in cardiac arrest, they collapse suddenly and:
- will be unconscious
- will be unresponsive and
- won’t be breathing or breathing normally – not breathing normally may mean they’re making gasping noises.
- A common cause of cardiac arrest is a life-threatening abnormal heart rhythm called ventricular fibrillation (VF).
- VF happens when the electrical activity of the heart becomes so chaotic that the heart stops pumping, instead, it quivers or ‘fibrillates’.
- The main causes of cardiac arrest related to the heart are:
- A heart attack (caused by coronary heart disease)
- Cardiomyopathy and some inherited heart conditions.
- Congenital heart disease.
- Heart valve disease.
- Acute myocarditis (inflammation of the heart muscle).
Some other causes of cardiac arrest include:
- A drug overdose.
- A severe hemorrhage (known as hypovolaemic shock) – losing a large amount of blood.
- Hypoxia – caused by a severe drop in oxygen levels.
CPR stands for cardiopulmonary resuscitation. It’s when someone gives chest compressions to a person in cardiac arrest to keep them alive until emergency help arrives.
Why CPR needs to be done when someone is in cardiac arrest
A cardiac arrest is a serious emergency. It happens when there’s an electrical problem in the heart and it suddenly stops pumping blood around your body. When your heart stops pumping blood, your brain gets no oxygen. It causes the person to fall unconscious and stop breathing. Without CPR the person will die within minutes.
CPR should only be done if someone is:
- Unconscious and not breathing.
- Unconscious and not breathing properly.
If their heart is beating but they’re not breathing.
This is called a respiratory arrest, and it’ll become a cardiac arrest quickly without CPR. Don’t waste time checking for a pulse – if someone is unresponsive and not breathing or not breathing normally then call 999 and start CPR.
Step 1: Shake and shout
If you come across someone who is unconscious, always check for hazards before you start helping.
Someone having a cardiac arrest will either not be breathing or won’t be breathing normally. They also won’t be conscious.
Check for a response – gently shake the person’s shoulders and ask loudly ‘are you alright?’
Shout for help – if someone is nearby, ask them to stay as you might need them. If you are alone, shout loudly to attract attention, but don’t leave the person.
Step 2: Call emergency lines
If the person is not breathing or not breathing normally:
Ask someone to call emergency lines immediately and ask for an ambulance
Ask someone to find a public access defibrillator (PAD).
If there’s no one around call emergency lines before starting compressions.
Step 3: Give chest compressions
Kneel next to the person.
Place the heel of one hand in the center of the chest. Place your other hand on top of the first. Interlock your fingers.
With straight arms, use the heel of your hand to push the breastbone down firmly and smoothly, so that the chest is pressed down between 5–6 cm, and released.
Do this at a rate of 100 to 120 chest compressions per minute – that’s around 2 per second. We tell people to think of Stayin’ Alive by the Bee Gees and push to the beat.
Step 4: Keep going
Keep going until professional help arrives and takes over, or the person starts to show signs of regaining consciousness, such as coughing, opening their eyes, speaking, or breathing normally.
If you’re feeling tired, and there’s someone nearby to help, ask them to take over giving CPR. You can show them what to do and take turns until emergency help arrives.
Step 5: Use a defibrillator
As soon as a defibrillator is found turn it on and follow its clear instructions.
The defibrillator will decide whether a shock is needed and if so, it will tell you to press the shock button. An automatic defibrillator will shock the person without prompt. Don’t touch the person while they’re being shocked.
The advice for giving CPR to babies or children is different from adults.
In CPR a baby is under the age of 1 year. A child is between 1 year and 18 years of age.
Before starting CPR on a baby or child:
- Check the space is clear and look out for hazards like electrical equipment, slippery surfaces, or cars.
- See if their chest rises and listen or feel for breathing.
- Try to talk to the child by asking ‘are you ok?’
- If they are conscious but can’t move, don’t start CPR and call an ambulance immediately.
If the child or baby doesn’t react and is unconscious, shout for someone to call emergency lines and tell them to get a defibrillator. Start CPR immediately.
How to do Child CPR:
- Turn the child on their back, open their mouth and tilt their head back.
- Pinch their nose, seal their mouth with yours and breathe in firmly until their chest rises. At first, give 5 of these rescue breaths.
- Put one hand in the center of the child’s chest (aim for their breastbone). Push down on their chest about one-third deep. Repeat this 30 times to a steady and swift beat. Allow the chest to come back up before you push each time.
- After doing 30 chest compressions, give 2 rescue breaths. Keep going with 30 chest compressions and 2 rescue breaths.
- Do this until emergency help arrives or the child shows signs of consciousness (breathing, opening eyes, moving).
You can stop CPR and use a defibrillator when someone finds one and it’s turned on. Continue CPR whilst it tells you what to do.
Don’t leave the child alone and look for a defibrillator yourself unless someone else is taking over.
The advice for giving CPR to a child (ages 1-18) and a baby (1 year old and under) is slightly different.
For infants, use the steps above but:
- Use two fingers and not your hand for chest compressions. If you can’t push down at least 4cm with two fingers, then use your two thumbs or hand
- Instead of covering their mouth with yours, cover their nose and mouth when giving rescue breaths, if possible.
If the child or baby starts to show signs of life:
- stop compressions but carry on with rescue breaths until they can do it alone.
- turn the child into the recovery position.
- monitor to see if their breathing stops again.
- wait for emergency services.