CPR, or cardiopulmonary resuscitation, keeps blood flowing to the brain and heart when someone’s heart stops. Bystanders who perform CPR before paramedics arrive give the person a 28% greater chance of survival compared to doing nothing. You don’t need medical training or certification to do it, and the basics can be learned in minutes.
Recognizing Cardiac Arrest
Cardiac arrest causes a person to collapse and lose consciousness within seconds. The key signs are simple: the person is unresponsive and not breathing normally. What trips people up is gasping. More than half of cardiac arrest patients will gasp, and bystanders sometimes mistake this for real breathing. These gasps sound like snoring, gurgling, moaning, or snorting. They’re a survival reflex triggered by the brain, not effective breathing, and they typically stop within about four minutes. If someone has collapsed and is only gasping, they need CPR immediately.
Rarely, a person in cardiac arrest may have a brief seizure, which can also cause confusion about what’s happening. The bottom line: if someone suddenly collapses, is unresponsive, and isn’t breathing normally, call 911 and start chest compressions.
How CPR Keeps Someone Alive
When the heart stops pumping on its own, pressing hard and fast on the chest does the pumping manually. Each compression squeezes blood out of the heart and through the body, delivering whatever oxygen remains in the bloodstream to the brain and vital organs. This works through two mechanisms: direct compression of the heart between the breastbone and spine, and changes in pressure inside the chest cavity that push blood forward through the vessels.
CPR doesn’t restart the heart. What it does is buy time, keeping the brain supplied with enough oxygen to prevent irreversible damage until a defibrillator or paramedics can restore a normal heartbeat.
Hands-Only CPR for Adults
For adults who collapse in front of you, hands-only CPR (compressions without rescue breaths) is just as effective as traditional CPR with mouth-to-mouth when started in the first few minutes. This is the version the American Heart Association recommends for untrained bystanders, and it removes the barrier that keeps many people from acting.
Here’s how to do it:
- Call 911 first (or have someone else call while you start).
- Position your hands. Place the heel of one hand on the center of the person’s chest, right on the breastbone. Put your other hand on top and interlace your fingers.
- Push hard and fast. Compress the chest at least 2 inches deep at a rate of 100 to 120 compressions per minute. That pace is roughly the tempo of the song “Stayin’ Alive.”
- Don’t stop. Keep compressing until paramedics arrive or an AED is available.
Depth and speed matter more than anything else. Compressions that are too shallow don’t move enough blood. Leaning on the chest between compressions prevents the heart from refilling. Lock your elbows, use your body weight, and let the chest fully recoil after each push.
CPR for Children and Infants
Children and infants need modified technique because their bodies are smaller and more fragile. For a child between 1 and 8 years old, place the heel of one hand on the breastbone just below the nipple line (not at the very bottom of the breastbone) and compress about one-third to one-half the depth of the chest. You can use one hand instead of two if the child is small enough.
For infants under 1 year old, use two fingers placed on the breastbone just below the nipple line. Compress about 1.5 inches deep. Rescue breaths are more important for children and infants than for adults, because their cardiac arrests are more often caused by breathing problems rather than heart rhythm issues. If you’re trained in rescue breathing, alternate 30 compressions with 2 gentle breaths. If you’re not, compressions alone are still far better than doing nothing.
Using an AED During CPR
An automated external defibrillator, or AED, is the device that can actually restart a normal heart rhythm. They’re found in airports, gyms, offices, and many public buildings. AEDs are designed for untrained people to use: they give voice prompts and will not deliver a shock unless the heart needs one.
If an AED is nearby, have someone grab it while you keep doing compressions. When it arrives, turn it on and follow the voice instructions. You’ll attach two adhesive pads to the person’s bare chest (the pads have diagrams showing where they go). The AED will then analyze the heart rhythm. At this point, everyone must stop touching the person. Say “clear” out loud. If the AED advises a shock, press the button. If it says no shock is needed, or after the shock is delivered, immediately resume chest compressions. Don’t wait. Get right back on the chest and keep going.
Broken Ribs and Other Injuries
Effective CPR often causes injuries, and that’s expected. Rib fractures are the most common, occurring in roughly 55% of people who receive CPR. Sternum fractures happen in about a third of cases. Less commonly, CPR can cause a collapsed lung (around 3% of cases) or minor liver injury (under 1%).
These numbers can feel alarming, but context matters. A person in cardiac arrest is clinically dead. Broken ribs heal. Brain death from oxygen deprivation does not. If you hear or feel a crack while performing compressions, keep going. You are not making things worse. Medical teams expect these injuries and consider them an acceptable trade-off.
Legal Protections for Bystanders
Every U.S. state has some form of Good Samaritan law that protects bystanders who provide emergency care in good faith. These laws exist specifically to encourage people to act without fear of being sued. If you crack someone’s ribs during CPR, that falls squarely under ordinary negligence, the kind of mistake any reasonable person might make while trying to help, and Good Samaritan laws cover it.
The protections apply as long as you meet a few common-sense conditions: the situation is a genuine emergency, you’re acting voluntarily and without expectation of payment, you have the person’s consent (or they’re unconscious and can’t give it), and you’re not recklessly careless. Gross negligence, like performing CPR on someone who is clearly breathing normally, or attempting procedures far beyond your training, would not be protected. But stepping in to do chest compressions on someone who has collapsed and isn’t breathing? That’s exactly the scenario these laws were written for.
What Happens When Paramedics Arrive
Keep performing CPR until emergency medical services take over. When paramedics arrive, they’ll tell you to step back. They’ll assess the rhythm, use advanced equipment, and transport the person to a hospital. Your job at that point is done. The minutes you spent doing compressions may have preserved enough brain function to give that person a real chance at recovery.
If you haven’t taken a CPR class, most local Red Cross chapters and fire departments offer them for free or at low cost. A typical class runs about two hours and gives you hands-on practice with a mannequin, which builds the muscle memory and confidence that make a real difference when seconds count.