CPR is an emergency life saving procedure consisting of timed compression of external chest wall with alternating mouth to mouth breathing.
First you have to make sure that the scene is safe to help the victim and perform CPR. Determine whether the victim is responsive or not by tapping on the shoulder and shouting at them "are you ok?" If there is no response than 911 should be called. In the unconscious victim, the most common airway obstruction is the tongue. Roll the victim on their back, open the airway by tilting the head back gently with one hand and gently lift the chin forward with the other hand, this may allow breathing to resume.
Check if the victim is breathing by looking for chest movement, listening for normal breath sounds and feeling any air movement on your cheek for 5 - 10 seconds. If there is no breathing than start CPR. Pinch nose shut and start mouth to mouth breathing by making a tight seal around the victim's mouth with yours, give 2 slow breaths making sure that the person's chest rises with each breath.
Immediately after giving the 2 breaths start chest compression by placing the heal of one hand on the center of the victims chest between the nipples. Place your other hand on top of the first hand, your elbows should be kept straight with your shoulders positioned directly above your hands. Using your body weight press down on the chest with enough force to compress the chest down about 2 inches, compress the chest at a rate of 100 compressions per minute. After doing 30 compressions, stop and open the airway by head tilt, chin lift, pinch the nose shut and start mouth to mouth breathing, give 2 slow breaths. This is one cycle. Each cycle consists of 30 compressions and 2 breaths. Each cycle is done in about 24 seconds. After 5 cycles which takes about 2 minutes, stop and check for breathing. If there is no breathing, continue CPR until emergency medical help arrives and take over.
See the following link for a new CPR method.
This information is not intended nor implied to be a substitute for professional medical advice; it should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. Call 911 for all medical emergencies.