A person is likely to be in cardiac arrest if they are unresponsive and not breathing normally. The key signs are:
Unresponsive: they do not react when you tap their shoulders and call to them.
Not breathing normally: they are making no breathing movements, or they are making occasional gasping or snorting sounds. These gasps \u2014 known as agonal breathing \u2014 are a sign of cardiac arrest and should not be mistaken for normal breathing.
You should not spend more than 10 seconds checking for breathing. If you are not sure whether someone is breathing normally, treat them as if they are in cardiac arrest \u2014 call 999 and start CPR immediately.
You do not need to check for a pulse. Unless you are a trained healthcare professional, pulse checks are unreliable and take too long. If someone is unresponsive and not breathing normally, start CPR. You cannot make the situation worse by acting.