1) Cardiopulmonary resuscitation (CPR) should be performed immediately when an individual is unresponsive and not breathing or circulating adequately.
2) Brain damage can occur within 3-4 minutes of no circulation, so CPR is crucial to perform as early as possible to increase chances of survival.
3) The basic steps of CPR are to check for responsiveness, open the airway, check for breathing, and if needed perform rescue breathing and chest compressions in a 15:2 ratio at 100-120 compressions per minute until emergency help arrives.