When performing CPR, you have to check for three things before doing so.
1. If they are unconscious. If you can’t find a way to wake them up, then it would be in your best interest to think about doing CPR
2. Breathing problems can indicate that something is very wrong. Usually if they aren’t breathing, their heart probably isn’t beating either
3. No pulse should be a definite reason to do CPR. If their heart has stopped, they aren’t delivering oxygen to their body, and they can risk dying
If your patient has any of these, you should begin CPR.