CPR is a lifesaving procedure that is performed when someone's breathing or heartbeat has stopped, as in cases of electric shock, drowning, or heart attack. CPR is a combination of:

• Rescue breathing, which provides oxygen to a person's lungs.
• Chest compressions, which keep the person's blood circulating.

Permanent brain damage or death can occur within minutes if a person's blood flow stops. Therefore, you must continue these procedures until the person's heartbeat and breathing return, or trained medical help arrives.

CPR can be lifesaving, but it is best performed by those who have been trained in an accredited CPR course. The procedures described here are not a substitute for CPR training. (See www.americanheart.org for classes near you.)

Time is very important when dealing with an unconscious person who is not breathing. Permanent brain damage begins after only 4 minutes without oxygen, and death can occur as soon as 4 - 6 minutes later.

When a bystander starts CPR before emergency support arrives, the person has a much greater chance of surviving. Nevertheless, when most emergency workers arrive at a cardiac arrest, they usually find no one giving CPR.

Machines called automated external defibrillators (AEDs) can be found in many public places, and are available for home use. These machines have pads or paddles to place on the chest during a life-threatening emergency. They use computers to automatically check the heart rhythm and give a sudden shock if, and only if, that shock is needed to get the heart back into the right rhythm.

When using an AED, follow the instructions exactly.

In adults, major reasons that heartbeat and breathing stop include:

• Drug overdose
• Excessive bleeding
• Heart disease (heart attack or abnormal heart rhythm)
• Infection in the bloodstream (sepsis)
• Injuries and accidents