Cardiopulmonary resuscitation (CPR) is a lifesaving technique. It aims to keep blood and oxygen flowing through the body when a person’s heart and breathing have stopped.

CPR can be performed by any trained person. It involves external chest compressions and rescue breathing.

CPR performed within the first six minutes of the heart stopping can keep someone alive until medical help arrives.

Although rescue breathing techniques were used to revive drowning victims as early as the 18th century, it wasn’t until 1960 that external cardiac massage was proven to be an effective revival technique. The American Heart Association (AHA) then developed a formal CPR program.

While there’s no substitute for formal CPR training taught by certified instructors, the AHA recently recommended that people who haven’t received CPR training initiate “hands-only” CPR. This method removes the rescue breathing and is easy to perform, proven to save lives, and better than waiting until trained help arrives.

People without CPR training can perform hands-only CPR by following the steps below.

1. Survey the scene

Make sure it’s safe for you to reach the person in need of help.

2. Check the person for responsiveness

Shake their shoulder and ask loudly, “Are you OK?” For an infant, tap the bottom of the foot and check for a reaction.

3. If the person isn’t responsive, seek immediate help

Call 911 or your local emergency services if the person isn’t responsive. You can also ask someone else to call. If you’re alone and believe the person is a victim of drowning, or if the unresponsive person is a child from age 1 to 8, begin CPR first, perform it for two minutes, then call emergency services.

4. Check the heart with an automated external defibrillator (AED)

If an AED is readily available, use it to check the person’s heart rhythm. The machine may also instruct you to deliver one electric shock to their heart before beginning chest compressions.

If the person is a child from age 1 to 8, perform CPR first for two minutes before checking their heart with an AED. Use the device’s pediatric pads if they’re available.

The use of an AED in infants under 1 years old isn’t conclusive or strongly recommended.

If an AED isn’t immediately available, don’t waste time looking for the device. Start chest compressions immediately.

5. Locate hand position

If the person is an adult, place the heel of one of your hands in the center of their chest, between the nipples. Put your other hand on top of the first. Interlock your fingers so they’re drawn up and the heel of your hand remains on their chest.

For children from age 1 to 8, use just one of your hands in the center of their chest.

For infants, place two fingers in the center of their chest, slightly below the nipple line.

6. Begin compressions

To start compressions on an adult, use your upper body to push straight down on their chest at least 2 inches. Perform these at a rate of 100 to 120 compressions per minute. Allow their chest to recoil between compressions.

For children from ages 1 to 8, push straight down on their chest about 2 inches at a rate of 100 to 120 compressions per minute. Allow their chest to recoil between compressions.

For an infant, push straight down on their chest 1½ inches at a rate of 100 to 120 compressions per minute. Once again, let the chest recoil between compressions.

7. Continue compressions

Repeat the compression cycle until the person starts to breathe or medical help arrives. If the person begins to breathe, have them lie on their side quietly until medical assistance is on the scene.

When the AHA revised its CPR guidelines in 2010, it announced that chest compressions should be performed first before opening the person’s airway. The old model was ABC (Airway, Breathing, Compressions). This was replaced by CAB (Compressions, Airway, Breathing).

In the first few minutes of cardiac arrest, there’s still oxygen in the person’s lungs and bloodstream. Starting chest compressions first on someone who’s unresponsive or not breathing normally can help send this critical oxygen to the brain and heart without any delay.

If you’re trained in CPR and come across someone who’s unresponsive or having difficulty breathing, follow the steps for hands-only CPR for 30 chest compressions.

Then perform the following actions:

1. Open the airway

Put the palm of your hand on the person’s forehead and tilt their head back. Gently lift their chin forward with your other hand.

For infants and children from age 1 to 8, a head tilt alone will often open their airway.

2. Give rescue breaths

Rescue breaths are appropriate for anyone age 1 and older. With the airway open, pinch the nostrils shut, and cover the person’s mouth with a CPR face mask to make a seal. For infants, cover both mouth and nose with the mask. If a mask isn’t available, cover the person’s mouth with yours.

Give two rescue breaths, each lasting about 1 second.

Watch for their chest to rise with each breath. If it doesn’t, reposition the face mask and try again.

3. Alternate rescue breathing with chest compressions

Continue alternating 30 compressions with two rescue breaths until the person begins to breathe or until medical help arrives.

If the person begins to breathe, have him or her lie on their side quietly until medical assistance is on the scene.

Many humanitarian and nonprofit organizations provide CPR and AED training. The American Red Cross offers courses in CPR and combined CPR/AED techniques, as does the AHA.

The AED can detect abnormalities in a person’s heart rhythm and, if needed, deliver an electric shock to the chest to restore normal rhythm to the heart. This is known as defibrillation.

Sudden cardiac arrests are often caused by a fast and irregular heart rhythm that begins in the heart’s lower chambers, or ventricles. This is ventricular fibrillation. An AED can help restore the heart’s normal rhythm and even help revive a person whose heart has stopped functioning. Learn more about how the heart works.

With training, an AED is easy to use. When used properly in conjunction with CPR, the device greatly increases a person’s chances for survival.