person performing CPR on unconscious person

CPR Saves Lives and Brains

When someone experiences cardiac arrest, the time between collapse and the start of CPR/defibrillation is the difference between life and death. We spoke to cardiologist Jennifer Haythe, MD, associate professor of medicine at Columbia University Vagelos College of Physicians and Surgeons and associate director of Columbia’s Adult Pulmonary Hypertension Program, to find out more.

When does someone need CPR?

A person needs CPR when they are having a cardiac arrest: sudden collapse, loss of pulse, loss of breathing, and loss of consciousness.

If you see someone in cardiac arrest, call 911, then start CPR. Keep doing CPR until someone formally trained in CPR or an automated external defibrillator (AED) arrives. AEDs are becoming more available and can be used by people without training. They electrically shock the heart, causing it to start beating again. CPR and AEDs save lives. 

What is cardiac arrest?

A cardiac arrest refers to the loss of cardiopulmonary circulation, the circulation of blood through the heart. Simply: The heart stops beating or suddenly develops an arrhythmia (irregular heartbeat) and cannot pump blood effectively to the lungs, brain, and rest of the body. Someone in cardiac arrest has no pulse (heartbeat) and is usually not breathing.

Cardiac arrest is life threatening. A person in cardiac arrest needs cardiopulmonary resuscitation (CPR) and/or defibrillation to start within seconds.

What are the signs of cardiac arrest?

Sudden collapse. No pulse. No breathing. Loss of consciousness. The person does not respond even if you shake them or yell at them.

Female physician in blue uniform illustrates to measure heart rate, simply check the pulse at your neck.

How can you tell if someone has no pulse?

To check for a pulse, place your index and middle fingers on the side of the neck in the space next to the windpipe.

Do you need training to give someone CPR?

If nobody starts CPR, the person will die. If nobody around the person is trained in CPR, it is still worth trying.

  • Clasp your hands together;
  • Place them in the middle of the person's upper chest;
  • Start compressing (pushing down with hard pressure) their chest, hard and fast, 100-120 pushes per minute, until someone trained can relieve you.
  • If you hear ribs cracking that is OK—continue to deliver CPR.

CPR takes only two minutes to learn. Go to the American Heart Association's hands-only CPR page to learn today.

What is a good CPR chest compression and why is it important?

Compressions help keep blood flowing throughout the body.

In adults, high-quality CPR includes a compression rate of 100-120/minute and a compression depth of at least 50 mm (2 inches).

In infants and children, the compression depth should be at least 1/3 of their anteroposterior chest diameter (distance from front to back).

What do doctors watch for after cardiac arrest?

After resuscitation from a cardiac arrest, doctors look for any signs of neurologic injury, cardiac injury, or other organ dysfunction.

The brain is exquisitely sensitive to oxygen. This is one reason CPR and/or defibrillation is urgent and vital. During cardiac arrest, oxygen does not get to the brain, and brain recovery can be slow.


Jennifer Haythe, MD, is a cardiologst who specializes in heart failure, cardiac transplant, pulmonary hypertension, women's cardiovascular disease, and cardio-obstetrics. She is associate professor of medicine in the Division of Cardiology at Columbia University Vagelos College of Physicians and Surgeons, associate director of the Adult Pulmonary Hypertension Program, and director of the Cardio-Obstetrics Program at Columbia University Irving Medical Center.