If someone near you collapses and isn’t breathing normally, you can double their chance of survival by starting chest compressions immediately and calling 911. Bystander CPR raises the likelihood of surviving to hospital discharge from about 5.5% to over 10%, and that benefit holds true regardless of the person’s age. You don’t need certification or training. Here’s exactly what to do.
Recognize Cardiac Arrest
Cardiac arrest looks like this: a person suddenly collapses, doesn’t respond when you tap their shoulders and shout, and isn’t breathing normally. That last part trips people up, because more than half of cardiac arrest victims gasp, snort, or make gurgling sounds in the first minutes. These “agonal” breaths are not real breathing. They’re reflexive, irregular, and often sound labored or strange. In about 20% of cardiac arrest cases, 911 dispatchers never send CPR instructions because the caller reported the person was still breathing, when what they were actually seeing was agonal gasping.
Don’t wait to be sure. If someone is unresponsive and either not breathing or only gasping irregularly, treat it as cardiac arrest and act.
One distinction worth understanding: cardiac arrest is not the same as a heart attack. A heart attack is a blockage that cuts off blood flow to part of the heart muscle. The person is usually conscious, often clutching their chest. Cardiac arrest is an electrical malfunction that causes the heart to stop pumping altogether. The person loses consciousness within seconds. A heart attack can trigger cardiac arrest, but they require very different responses.
Call 911 First
If you’re alone, call 911 before starting compressions. Put your phone on speaker and set it nearby. The dispatcher will stay on the line and walk you through every step, including compression pace and when to stop. Emergency dispatch centers are specifically trained to coach untrained bystanders through compression-only CPR in real time. If video calling is available, some dispatch centers can even watch and correct your technique remotely.
If other people are nearby, split the tasks: one person calls 911, one starts CPR, and a third searches for an AED (automated external defibrillator). Assign these jobs by pointing at specific people. Saying “someone call 911” often results in no one doing it.
Start Chest Compressions
Hands-only CPR is what current guidelines recommend for bystanders. No mouth-to-mouth is needed. Here’s the technique:
- Position: Place the person flat on their back on a firm surface. Kneel beside their chest.
- Hand placement: Put the heel of one hand on the center of the chest, right on the breastbone. Place your other hand on top and interlace your fingers.
- Depth: Push straight down at least 2 inches. This is deeper than most people expect. You need to compress the chest hard enough to physically squeeze the heart between the breastbone and spine.
- Rate: Compress at 100 to 120 pushes per minute. That’s roughly the tempo of the Bee Gees’ “Stayin’ Alive” or two pushes per second.
- Recoil: Let the chest come all the way back up between compressions. Leaning on the chest between pushes prevents the heart from refilling with blood.
Lock your elbows and use your body weight, not your arm muscles. Push from your shoulders. CPR is exhausting, and compression quality drops noticeably after about two minutes. If someone else is available, switch off every two minutes to keep compressions effective.
Don’t stop compressions to check for a pulse or signs of life. Keep going until paramedics arrive, an AED is ready to use, or the person starts moving, breathing normally, or speaking.
Use an AED If One Is Available
AEDs are designed so that anyone can use them with zero training. They’re found in airports, gyms, offices, schools, shopping malls, and many other public spaces, usually in wall-mounted cases near entrances or common areas. Early defibrillation is one of the strongest predictors of survival, so finding and using one quickly matters enormously.
Turn the AED on. It will begin giving you voice instructions immediately. It will tell you to expose the person’s bare chest and place two adhesive pads in specific positions (diagrams are printed on the pads). Once the pads are attached, the AED analyzes the heart rhythm automatically. If a shock is needed, it tells you to press a button. If no shock is needed, it will not deliver one, no matter what you press. You cannot accidentally shock someone who doesn’t need it.
After a shock, the AED will prompt you to resume chest compressions. It runs a two-minute countdown, then pauses you again to reanalyze the rhythm. This cycle of compressions and analysis continues until paramedics take over.
One important detail: don’t stop CPR to go find an AED yourself. Only send someone else to retrieve one. Uninterrupted chest compressions are the single most important thing you can provide.
What to Expect Physically
Effective CPR is rough. You may hear or feel ribs crack, especially in older adults. This is common, it means you’re compressing deeply enough, and it is far better than the alternative. A cracked rib heals. Without compressions, the person’s brain begins to suffer irreversible damage within four to six minutes.
The person may also vomit during CPR. If this happens, turn their head to the side, quickly clear the mouth, and resume compressions. Your goal is to keep blood circulating to the brain and vital organs until professional help arrives with advanced equipment.
When CPR Should Continue
Keep compressing until one of these things happens: paramedics arrive and tell you to stop, the person clearly regains consciousness (moving purposefully, breathing normally, speaking), or an AED advises no further shocks and the person is breathing. Fatigue alone is not a reason to stop unless no one else can take over. Even imperfect compressions are better than none.
For context, ambulance response times in the United States average around 7 to 14 minutes depending on location. That’s a long time to do CPR, but every minute of chest compressions buys the person time. Research consistently shows that longer delays without any bystander CPR are among the strongest predictors of death.
Legal Protection for Bystanders
Every U.S. state has a Good Samaritan law that protects people who voluntarily provide emergency care. These laws shield you from civil liability for ordinary mistakes, like cracking a rib during compressions, as long as you’re acting in good faith during a genuine emergency. You don’t need to be certified or trained. The protection generally applies as long as you act voluntarily, don’t accept payment, and don’t do something recklessly beyond your ability (like attempting a surgical procedure).
Good Samaritan laws serve as a legal defense if you’re sued. They won’t prevent a lawsuit from being filed, but they make it extremely difficult for anyone to win one against a bystander who performed reasonable emergency CPR. The far greater legal and moral risk is doing nothing. Cardiac arrest is fatal within minutes without intervention, and bystanders who act are protected by both law and overwhelming medical consensus that any attempt at CPR is better than standing by.