Anyone can learn how to perform CPR via an online or in-person training workshop. Here are the basic principles and techniques involved in cardiopulmonary resuscitation.

What to Do If Someone Needs CPR

Ideally, everyone would be trained in CPR. If you're not, you may be afraid to try to help someone in an emergency. Still, it's always better to do what you can than to do nothing at all if it means potentially saving a person's life. The American Heart Association recommends a slightly different approach to doing CPR depending on how well-trained you are:1

• If you are trained: Check to see if the person has a pulse and is breathing. If there is no pulse or breathing within 10 seconds, start CPR with 30 chest compressions followed by two rescue breaths. Repeat the sequence until the person starts breathing.
• If you are untrained, or trained but not too confident in your abilities: If you've never been trained in CPR, or have been but are unsure about giving rescue breaths, then use hands-only CPR. Hands-only CPR involves uninterrupted chest compressions of 100 to 120 per minute until an EMT arrives. You do not include rescue breathing with this technique.
  
  If you have not had CPR training or don't feel comfortable giving rescue breaths, just keep pushing on the chest until help arrives.

  What to Do Before Performing CPR

  Time is of the essence, but before you attempt CPR on someone, follow these steps:4
  
  1. Make sure the environment is safe. A fire, traffic accident, or other dangers could put your own life at risk.
  2. Try to wake the person. Tap on the person's shoulder firmly and ask "Are you OK?" in a loud voice. Move on to the next steps after five seconds of trying to wake the patient.
  3. Call 911. Anytime a patient won't wake up, call 911 immediately or ask a bystander to call. Even if you will perform CPR on the spot, it's important to get paramedics to the scene as quickly as possible.
  4. Put the person on their back. If it's possible that the person may have had a spinal injury, turn them carefully without moving the head or neck.
  5. Check for breathing. Tilt the patient's head back to open the airway and determine if they are breathing. If the patient doesn't take a breath after 10 seconds, start CPR.
     
     

     How to Do CPR

     Once you have followed the above steps, here is how to perform CPR. Techniques vary slightly based on the age of the person.
     

     Adults

     The following steps apply to adults and to children over 8 years old.2
     

     1. Place your hands on the person's chest.Imagine a line between the nipples and put the heel of one hand directly on that line, in the center of the chest (i.e., the sternum). Place your other hand on top of that hand. Center your weight directly over your hands.
     2. Perform chest compressions. Push hard, to a depth of at least 2 inches (but no deeper than 2.4 inches) and fast—about twice per second until the person responds. Your hands shouldn't bounce, but you should lift your entire body weight off the patient in between each compression.5
     3. Give rescue breaths. If you have had CPR training and feel comfortable performing the steps, push on the chest 30 times, then give two rescue breaths.
     4. Repeat. Repeat cycles of 30 chest compressions and two breaths until help arrives or the patient wakes up.

     Children 1 to 8 years old

     The procedure for giving CPR to a child between 1 to 8 is essentially the same as that for an adult.5
     

     1. Place your hands on the child's chest.Place two hands (or one hand if the child is very small) on the child's sternum.
     2. Perform chest compressions. Push hard, to a depth of at least 2 inches (but no deeper than 2.4 inches) and fast—about twice per second until the person responds.
     3. Give rescue breaths. If you have had CPR training and feel comfortable performing the steps, push on the chest 30 times, then give two rescue breaths.
     4. Repeat. Repeat cycles of 30 chest compressions and two breaths until help arrives or the patient wakes up.

     Infants

     1. Flick the bottom of the foot to elicit a response. This takes the place of shaking the shoulders of an older person.
     2. Place two fingers of one hand in the center of the chest.
     3. Give chest compressions. Gently use your fingers to compress the chest about 1.5 inches deep. Perform two compressions per second, just as you would when giving an adult CPR.
     4. Perform rescue breathing. If you are comfortable giving rescue breaths, give two of them between each series of 30 chest compressions, just as you would with an older person.6

     What Each Step Does

     Each step of CPR serves an important purpose. Here's what each one does:
     

     Asking If the Person Is OK

     Before attempting CPR, it's important to make sure the person actually needs it. If the person wakes up when you shake them gently and talk to them, don't start CPR, but do get medical help right away, especially if they seem confused or are unable to speak.
     

     Calling 911

     Even if you end up reviving the person with CPR, they will need to be taken to the hospital by an ambulance as soon as possible. If you don't succeed, an EMT may be able to resuscitate the person with medical equipment, such as an automated external defibrillator (AED).7 An EMT may also be able to talk you through performing CPR steps while they're en route.
     

     Chest Compressions

     Compressing the chest moves blood through the brain, keeping it working until the heart can get started again. It's critical to keep the blood flowing without interruption. It is possible to revive someone with chest compressions alone (without rescue breathing).
     

     Rescue Breathing

     Formerly known as mouth-to-mouth resuscitation, rescue breathing is intended to use your own breath to fill the person's lungs with air and restore their ability to breathe.
     Rescue breathing has become one of the most controversial steps in CPR. The debate is ongoing about how much is enough (or too much) and whether it's even necessary.8 If you do perform rescue breaths, make sure you know how to do it correctly.
     
     

     How to Get Certified

     You can get certified in CPR by meeting the requirements of a CPR training program. These programs are offered in-person, online, or as a hybrid of both.9
     Classes are typically completed in two hours, depending on which format you choose (as you can go at your own speed with online training). Once you have completed the class, you will be able to get a certificate.10
     CPR training courses are offered by hospitals, community centers, and national organizations such as the American Red Cross and the American Heart Association.
     Not every CPR class is the same. There are CPR classes for healthcare professionals as well as CPR classes for the layperson. Before you take a CPR class, make sure the class is right for you.