Can you tell me about the “new” CPR?

DEAR DOCTOR K:

I thought CPR involved chest compressions, breathing into a person’s mouth and checking their pulse. But my daughter told me that the “new” CPR involves only chest compressions. Is this correct?

DEAR READER:

That’s right. Since 2008, the American Heart Association has recommended “hands only” cardiopulmonary resuscitation (CPR) if an adult suddenly collapses.

Cardiac arrest is usually to blame when someone collapses and stops breathing. It occurs when the heart’s electrical system malfunctions. The heart beats rapidly and chaotically — or stops beating altogether. The person stops breathing and becomes unresponsive.

In contrast, when people faint they also lose consciousness for a brief period, but they don’t stop breathing. You don’t want to perform CPR when someone has fainted, so be sure you have determined if the person is breathing.

If someone goes into cardiac arrest, first call 911, then immediately perform CPR. Place the palm of your non-dominant hand on the center of the person’s chest. If, like most people, you’re right-handed, you would place the palm of your left hand on the center of the chest.

Then with the dominant hand (your right hand, in this example), push down forcefully onto the top of your left hand, at about 100 times a minute. Pushing down this way squeezes blood out of the heart and keeps it flowing throughout the body. Every part of that person’s body needs a constant circulation of blood. The brain needs it most: If it doesn’t have a circulation of blood for more than four minutes, brain cells start to die.

In adults with cardiac arrest, this hands-only approach is just as effective — and possibly better — than CPR with rescue breathing. That’s because a person who suddenly collapses has a fair amount of oxygen in his or her bloodstream and doesn’t need the extra oxygen supplied by rescue breathing. Stopping compressions for rescue breathing may do more harm than good because it temporarily stops blood flowing to the brain.

All 911 operators are trained to give verbal cues for CPR. You can put your phone on speaker and ask the operator to talk you through the steps. The operator will count out loud to help you administer compressions at about 100 beats per minute.

CPR can be the difference between life and death. It keeps blood circulating until the person’s heart can be shocked back into a normal rhythm with an automated external defibrillator (AED). Emergency personnel will bring and use an AED. Many public areas have AEDs, which use voice prompts, lights and text messages to guide users (even people who haven’t been trained) through the steps.

The AHA, American Red Cross and other organizations offer classes on CPR and using a public defibrillator. You can also learn CPR by using a smartphone app or watching a brief video at www.heart.org/HandsOnlyCPR. It’s worth the time and effort. Four out of every five cardiac arrests happen at home, so the person you save is likely to be someone you love.

(Dr. Komaroff is a physician and professor at Harvard Medical School.)

(This column ran originally in September 2014.)