Who and how you should perform CPR:

•  If not trained in CPR, then provide hands-only CPR : means uninterrupted chest compressions of 100 to 120 a minute until paramedics arrive. You don't need to try rescue breathing.

• Trained and ready to go. If you're well-trained and confident in your ability, check to see if there is a pulse and breathing. If there is no breathing or a pulse within 10 seconds, begin chest compressions. Start CPR with 30 chest compressions before giving two rescue breaths.

• Trained but rusty. If you've previously received CPR training but you're not confident in your abilities, then just do chest compressions at a rate of 100 to 120 a minute. (Details described below.)