Check the scene for immediate danger. Make sure you're not putting yourself in harm's way by administering CPR to someone unconscious. Is there a fire? Is the person lying on a roadway? Do whatever is necessary to move yourself and the other person to safety.
If there is anything that could endanger you or the victim, see if there is something you can do to counteract it. Open a window, turn off the stove, or put out the fire if possible.
However, if there is nothing you can do to counteract the danger, move the victim. The best way to move the victim is by placing a blanket or coat underneath their back and dragging it.
Assess the victim's consciousness. Gently tap his or her shoulder and ask "Are you OK?" in a loud, clear voice. If he or she responds, CPR is not required. Instead, undertakebasic first aid and take measures to prevent or treat shock, and assess whether you need to contact emergency services.
If the victim does not respond, continue with the following steps.
Send for help. The more people available for this step, the better. However, it can be done alone. Send someone to call for emergency medical services (EMS).
Call 999 or 112.
Give the dispatcher your location, and notify him or her that you're going to perform CPR. If you're alone, get off the phone and start compressions after that. If you have someone else with you, have him or her stay on the line while you do CPR on the victim.
Do not check for a pulse. If you're not a trained medical professional, odds are you'll spend too much valuable time looking for a pulse when you should be doing compressions.
Check for breathing. Put your ear close to the victim's nose and mouth, and listen for slight breathing. If the victim is coughing or breathing normally, do not perform CPR. Doing so could cause the heart to stop beating.
Place the victim on his or her back. Make sure he or she is lying as flat as possible - this will prevent injury while you're doing chest compressions.
Place the heel of one hand on the victim's breastbone, exactly between the nipples.
Place your second hand on top of the first hand, palm-down.
Position your body directly over your hands, so that your arms are straight and somewhat rigid.
Perform 30 chest compressions. Press down with both hands directly over the breastbone to perform a compression, which helps the heart beat. Chest compressions are more critical for correcting abnormal heart rhythms (ventricular fibrillation or pulseless ventricular tachycardia).
You should press down by about 2 inches (5 cm).
Do the compressions in a relatively fast rhythm. Some agencies recommend doing compressions to the beat of the chorus of "Stayin' Alive," a 1970s disco hit, or at roughly 103 beats per minute. (You can listen to it here.)
Minimize pauses in chest compression that occur when changing providers or preparing for a shock. Attempt to limit interruptions to less than 10 seconds.
Make sure the airway is open. Place your hand on the victim's forehead and two fingers on their chin and tilt the head back to open the airway.
If there are no signs of life, place a breathing barrier (if available) over the victim's mouth.
Give two rescue breaths (optional). The American Heart Association no longer considers rescue breaths necessary for CPR, as the chest compressions are more important. You can give them if you choose to, though.
Keeping the airway open, take the fingers that were on the forehead and pinch the victim's nose closed. Make a seal with your mouth over the victim's mouth and breathe out for about one second. Make sure you breathe slowly, as this will make sure the air goes in the lungs and not the stomach.
If the breath goes in, you should see the chest slightly rise and also feel it go in. Give a second rescue breath.
Repeat the cycle of 30 chest compressions. If you're also doing rescue breaths, keep doing a cycle of 30 chest compressions and 2 rescue breaths.
You should do CPR for 2 minutes (5 cycles of compressions to breaths) before checking for signs of life.
Continue CPR until someone takes over for you, emergency personnel arrive, you are too exhausted to continue, an AED is available for immediate use, or signs of life return.
Use an AED (automated external defibrillator). If an AED is available in the immediate area, use it as soon as possible to jump-start the victim's heart.
Make sure there are no puddles or standing water in the immediate area.
Turn on the AED. It should have voice prompts that tell you what to do.
Fully expose the victim's chest. Remove any metal necklaces or underwire bras.
Check for any body piercings, or evidence that the victim has a pacemaker or implantable cardioverter defibrillator (should be indicated by a medical bracelet).
Make sure the chest is absolutely dry. Note that if the person has a lot of chest hair, you may need to shave it. Some AED kits come with razors for this purpose.
Attach the sticky pads with electrodes to the victim's chest. Follow the instructions on the AED for placement. Move the pads at least 1 inch (2.5 cm) away from any metal piercings or implanted devices.
Make sure no one is touching the person.
Press analyze on the AED machine. If a shock is needed, the machine will notify you.
If you do shock the victim, make sure no one is touching him or her.
Remove the electrode pads and resume CPR for another 5 cycles before using the AED again.
A video demonstration of performing CPR on an adult.
If you must move the victim, try to disturb the body as little as possible.
Get proper training from a qualified organization in your area. Training from an experienced instructor is the best way to be prepared in an emergency.
You can get guidance on correct CPR technique from an emergency services operator if needed.