Check for a response by gently shaking the person, and shout for help.

Call 999 on loudspeaker and tell them you are with someone who has collapsed and is not responding.

Look and listen for signs of normal breathing. The ambulance call handler will help you.

Interlock your fingers and start chest compressions twice per second. Don’t stop.

If you have been trained to provide rescue breaths, alternate 30 chest compressions with 2 rescue breaths.

The ambulance call handler will tell you where the nearest automated external defibrillator (AED) is. If someone is with you, ask them to fetch it and bring it back.

If you have a defibrillator, switch it on and follow the instructions.

Continue CPR until:  
- the AED asks you to pause while it reanalyses and gives another shock if needed  
- an ambulance arrives and tells you what to do  
- the person shows signs of life.