How Do You Know If Someone Needs CPR?

In the United States, around 350,000 people go into cardiac arrest outside of the hospital every year. While cardiopulmonary resuscitation (CPR) is an effective way to help in this situation, only about 40% of people who go into cardiac arrest receive bystander CPR before help arrives.

Knowing how to tell if someone needs CPR and being able to give it can buy a person time before emergency responders arrive—sometimes, it’s the difference between life and death. But not everyone knows when it’s appropriate or what to do.

Here’s how to quickly assess whether or not someone is a candidate for CPR.

What Happens When Someone Goes Into Cardiac Arrest?

Cardiac arrest means that the heart stops pumping blood to the rest of the body. Someone who is in cardiac arrest will have no pulse.

A person can go into cardiac arrest for many reasons, including:

• A heart attack or blockage in the arteries that supply blood flow to the heart
• Abnormal heart rhythms (arrhythmias)
• Illicit drug use or overdose
• Structural heart abnormalities (e.g., hypertrophic cardiomyopathy)
• Respiratory failure or arrest
• Severe electrolyte imbalance
• Chest trauma

What Does CPR Do?

When a person goes into cardiac arrest, blood isn’t getting to the rest of their body. That means no oxygen is circulating to the organs and tissues. The brain is the first organ to feel the effects of the lack of oxygen. Brain cells start to die within minutes and prolonged cardiac arrest can cause irreversible brain damage.

Chest compressions in CPR do the work of moving blood around the body that the heart would normally do by pumping. Doing compressions helps get oxygen to the brain and other vital organs.

Even if a person does not survive, doing CPR may serve another purpose: Helping to keep their organs viable if they're a donor.

How Effective Is CPR?

Medical dramas on TV have made people think that CPR is more likely to be life-saving than it really is. One study found that people believed the rate of survival with CPR was up to 75%. Over the last few decades, studies have looked at the actual survival rates for out-of-hospital CPR and come up with much lower numbers:

• A 2010 review of studies focused on over 150,000 patients found that when a person in cardiac arrest received bystander CPR, their survival rate was between 3.9% and 16.1%.
• Another study found that age matters, too: People in their 70s who got CPR had a survival rate of about 6.7%, while those in their 90s only had a 2.4% chance of survival.

If someone gets CPR and does survive cardiac arrest, they may still have a reduced quality of life or have lingering health problems, like severe fatigue, anxiety, and depression. If they were older or already had chronic health conditions, they may have even lower chances of survival.

When Should You Perform CPR?

If you witness someone going into cardiac arrest, the most important thing is to stay calm and assess the situation.

“When a person is in duress you will want to access the scene first, checking for any safety or hazards that may be harmful to you,” Zack Zarrilli, a paramedic and the founder of SureFireCPR.com, told Verywell.

After you’ve determined it’s safe to help, Zarrilli says the next step is to “tap the person’s shoulder, and shout ‘Are you OK? ’ while looking for normal breathing.”

If the person is conscious and breathing, they do not need CPR. However, if there is no response and the person is not breathing, Zarrilli says to make sure the person “is lying on a firm and flat surface facing upwards” and then start giving them CPR.

You should start CPR whether or not you can feel a pulse. In fact, the American Heart Association does not want people to spend time checking for a pulse. In an emergency, a nervous bystander may confuse their own pulse for that of the person they’re trying to help.

Even if someone is unresponsive and not breathing and still has a pulse, it probably isn’t strong enough to pump blood or it won’t last very long.

If you are alone, call 911 before starting chest compressions. Your goal is to get EMS on the way as soon as possible. Paramedics have medical devices that use electrical currents to correct abnormal heart rhythms (defibrillators). They’re also trained to give cardiac medications.

If there are other people around, point to a specific person and make eye contact with them. In a clear voice, tell them to “Call 911.” If there’s someone else around, you can tell them to look for an automated external defibrillator (AED), which anyone can use.

How to Do CPR Chest Compressions

Once you’ve determined that a person needs CPR and it’s safe for you to try to help, you can start giving chest compressions.

1. Look for the middle of the person’s chest.
2. Place the heel of one hand at the bottom of the breast bone (sternum) at the nipple line.
3. Stack your other hand on top and lace your fingers.
4. Position your body so that your shoulders are directly over your hands, with elbows straight and locked.
5. Push down hard and fast—you need the person’s chest to go down about 2 inches with each compression. Make sure to let their chest come back up each time before you push down again.

To get blood moving around the person’s body effectively, chest compressions need to be done at a rate of at least 100 beats per minute. To keep that rhythm, think of the beat of these songs:

• Stayin’ Alive by The Bee Gees
• Another One Bites the Dust by Queen
• Crazy in Love by Beyonce and Jay-Z
• Sweet Home Alabama by Lynyrd Skynyrd
• Rock Your Body by Justin Timberlake
• Hips Don’t Lie by Shakira

Doing high-quality chest compressions is physically exhausting. If someone else is around to help, you can switch after you’ve done 30 compressions.

When Should You Not Do CPR?

If someone is conscious and breathing, they don’t need CPR. There are also some specific situations when you should not try to give CPR.

The first is when it would put you in danger. You might be thinking more about trying to help someone, but you need to consider your own safety first.

“Do not begin CPR if the scene is unsafe for the person providing CPR or places the rescuer at risk,” said Zarrilli. “Some unsafe scene examples would be a chemical spill, an uncontrolled fire burning nearby, or an active shooter on a scene.”

Another situation is when a person would not want to get CPR. For example, people with end-stage chronic health conditions may have made a decision with their providers that if they go into cardiac arrest, they do not want any life-sustaining efforts made to save them. This is called a do-not-resuscitate (DNR) order. If you have evidence that someone has a DNR (such as a form from their medical record or a medical alert bracelet), you should not do CPR on them.

That said, in CPR training, you'll be told that since a person in cardiac arrest is unconscious, they can't tell you what they want or don't want. If you do not know for a fact that they do not want CPR and you don't have evidence (like a DNR), then you have to assume they would want help.

If you’re wondering if you’ll get in trouble for giving someone CPR, know that in most places you will be covered by Good Samaritan laws. You should learn about the specific laws in your state so you’ll know how you’ll be protected in the event you try to help someone in an emergency.