Call 911 immediately and start chest compressions. Every minute without blood flow reduces the chance of survival, and bystander CPR increases the likelihood of surviving to hospital discharge by 24%. You do not need training or certification to perform CPR. The 911 dispatcher will talk you through it in real time if you’ve never done it before.
How to Recognize Cardiac Arrest
Cardiac arrest looks nothing like a heart attack. The person collapses suddenly, loses consciousness, and stops breathing. There is no warning, no gradual buildup of symptoms. One moment they’re upright, the next they’re on the ground and unresponsive. A heart attack, by contrast, involves chest pain, shortness of breath, nausea, and sweating, and the person stays conscious.
The most common mistake bystanders make is confusing agonal breathing with normal breathing. In the first few minutes after the heart stops, a person may produce gasping, gurgling, snoring, or moaning sounds. These are not signs of breathing. They are reflexive movements that typically stop within about four minutes. Bystanders who hear these sounds often tell 911 dispatchers “they’re still breathing,” which delays life-saving instructions. If someone has collapsed, is unresponsive, and is making irregular gasping sounds, treat it as cardiac arrest.
Step-by-Step Bystander Response
1. Confirm They’re Unresponsive
Make sure the area around you is safe. Tap the person on the shoulder and shout “Are you okay?” If they don’t respond and aren’t breathing normally, move to the next step immediately.
2. Call 911 and Send for an AED
If other people are nearby, point to one specific person and tell them to call 911. Point to another and tell them to find an AED (automated external defibrillator). These are commonly mounted on walls in airports, gyms, schools, offices, and other public buildings. Be direct: make eye contact, use their name if you know it, and give a clear instruction. In a chaotic moment, vague requests get ignored.
If you’re alone, dial 911 yourself and put the phone on speaker. The dispatcher will guide you through CPR while you wait for paramedics. Studies show that dispatcher-assisted CPR instructions raise the rate of bystander CPR from about 17% to 26%, so even if you’ve never done this before, staying on the line makes a real difference.
3. Start Chest Compressions
Place the heel of one hand in the center of the person’s chest, between the nipples. Put your other hand on top, interlace your fingers, and lock your elbows straight. Position your shoulders directly over your hands so your body weight does the work.
Push hard and push fast. Compress the chest at least 2 inches deep at a rate of 100 to 120 compressions per minute. That tempo matches the beat of “Stayin’ Alive” by the Bee Gees, which is a genuinely useful mental reference. Let the chest fully recoil between each compression. Incomplete recoil reduces blood flow back to the heart.
If you’re not trained in CPR, do compressions only (called hands-only CPR) and skip rescue breaths. Hands-only CPR is effective for adults and far better than doing nothing. If you are trained, give 30 compressions followed by 2 rescue breaths: tilt the head back, pinch the nose, seal your mouth over theirs, and blow until you see the chest rise. Then immediately resume compressions.
4. Use an AED as Soon as It Arrives
AEDs are designed for untrained users. Open the case, turn it on, and follow the voice prompts. The device will tell you exactly where to place the adhesive pads on the person’s chest. Once the pads are attached, the AED analyzes the heart rhythm automatically. If it detects a rhythm that can be corrected with a shock, it will tell you to press the shock button. If no shock is needed, it will instruct you to continue CPR. You cannot accidentally shock someone who doesn’t need it.
Make sure no one is touching the person when the AED analyzes the rhythm or delivers a shock. After the shock, immediately resume chest compressions. Don’t wait to see if the person wakes up.
5. Keep Going Until Help Arrives
Alternate between CPR and AED use until paramedics take over or the person regains consciousness. High-quality compressions are exhausting. If another person nearby knows CPR, switch off every two minutes to keep the compressions effective. Fatigue leads to shallow compressions, which means less blood reaching the brain.
Why Speed Matters So Much
When the heart stops pumping, blood flow to the brain ceases. A person who goes less than 5 minutes without blood flow has a much higher likelihood of full recovery compared to someone who goes 30 minutes. Brain cells don’t die instantly, but the injury accumulates with every passing minute. Recent research from NYU Langone has shown that brain cells actually die more slowly than previously believed, over hours rather than minutes, but the damage that occurs in those first few minutes without intervention determines whether recovery is possible at all.
Chest compressions act as a manual pump, pushing oxygenated blood through the body until the heart can be restarted. Without them, survival rates for out-of-hospital cardiac arrest drop to around 5.5%. With bystander CPR, that number rises to about 10.2%. Those numbers may sound modest, but they represent thousands of lives each year.
Adjustments for Children and Infants
For children, the approach is similar but with a key difference in priority. In children, cardiac arrest is more often caused by a breathing problem than an electrical heart issue. Start CPR immediately rather than searching for an AED first. Use one hand instead of two for compressions on a small child, placed in the center of the chest. Compress to at least one-third the depth of the chest. Give 30 compressions followed by 2 rescue breaths, since rescue breathing is more critical for children than for adults.
For infants, use two fingers placed just below the nipple line instead of the heel of your hand. The same ratio applies: 30 compressions, then 2 gentle breaths. Cover both the infant’s mouth and nose with your mouth when giving breaths, and use only small puffs of air.
You Won’t Get Sued for Helping
Every U.S. state has some form of Good Samaritan law that protects bystanders who provide emergency care in good faith. As long as you act as a reasonably prudent person would under the same circumstances, you are shielded from civil liability. These protections cover CPR, AED use, and any reasonable effort to help at the scene of an emergency. The legal system recognizes that imperfect help is vastly better than no help at all.
Cracked ribs are common during effective CPR. This is a normal consequence of pressing 2 inches into someone’s chest, and it is not something you can be held liable for. A broken rib heals. Cardiac arrest without intervention is fatal.