CPR keeps blood flowing to the brain and organs when someone’s heart stops. The basic technique involves pushing hard and fast on the center of the chest at a rate of 100 to 120 compressions per minute, with a depth of at least 2 inches for adults. You don’t need certification to do it, and performing even imperfect CPR dramatically improves someone’s chance of survival compared to doing nothing.
Before You Start: Assess the Situation
Tap the person on the shoulders and shout, “Are you okay?” If there’s no response, check whether they’re breathing normally. Occasional gasping does not count as normal breathing. If they’re unresponsive and not breathing (or only gasping), call 911 immediately or have someone nearby call while you begin CPR. If an AED (automated external defibrillator) is available, have someone grab it.
Every minute without CPR reduces the person’s chance of survival. Don’t waste time second-guessing yourself.
Hands-Only CPR for Adults
If you haven’t been trained in CPR or you’re not comfortable giving rescue breaths, hands-only CPR is the recommended approach. Research shows that compression-only CPR performed by untrained bystanders produces better outcomes than standard CPR for adults with sudden cardiac arrest. The American Heart Association has recommended this approach since 2008.
Here’s what to do:
- Position your hands. Place the heel of one hand on the center of the person’s chest, right between the nipples. Stack your other hand on top and interlace your fingers.
- Lock your arms. Keep your elbows straight and position your shoulders directly above your hands. You’ll use your body weight, not your arm muscles, to compress the chest.
- Push hard and fast. Press down at least 2 inches into the chest at a rate of 100 to 120 compressions per minute. That’s roughly the tempo of the song “Stayin’ Alive.”
- Let the chest fully recoil. After each compression, let the chest come all the way back up before pushing again. Don’t lean on the chest between compressions.
Full chest recoil matters more than most people realize. When you let the chest spring back completely, it creates a suction effect inside the chest cavity that draws blood back toward the heart. Even slight leaning between compressions, as little as 10% of body weight resting on the chest, reduces blood flow and limits how much oxygen reaches the brain.
CPR With Rescue Breaths
If you’re trained and comfortable giving breaths, use a ratio of 30 compressions to 2 rescue breaths. After every 30 compressions, tilt the person’s head back slightly by lifting their chin, pinch their nose shut, and give two breaths into their mouth. Each breath should last about one second and make the chest visibly rise. Then immediately return to compressions.
Rescue breaths become especially important in certain situations. For cardiac arrests caused by drowning, drug overdose, or breathing problems, ventilation plays a crucial role because the underlying issue is a lack of oxygen rather than a heart rhythm problem. For children, studies show better outcomes with combined compression-and-ventilation CPR using either a 15:2 or 30:2 ratio compared to compressions alone.
CPR for Children and Infants
The technique changes slightly for smaller bodies. For children (roughly age 1 through puberty), use one or two hands depending on the child’s size, and compress the chest about 2 inches deep, or roughly one-third of the chest depth. For infants under 1 year old, use two fingers placed just below the nipple line and compress about 1.5 inches, again about one-third of the chest.
The compression rate stays the same: 100 to 120 per minute. If you’re alone with a child or infant who collapses, give 2 minutes of CPR before calling 911. This is different from adult CPR, where you call first. The reason is that cardiac arrest in children is more often caused by breathing failure than a heart rhythm problem, so those early compressions and breaths are critical.
How to Use an AED
An AED is a portable device that can shock the heart back into a normal rhythm. They’re designed for anyone to use, with step-by-step voice instructions that walk you through the entire process. You’ll find them in airports, gyms, schools, and many office buildings.
Turn the device on (open the lid or press the power button). Remove clothing from the person’s chest so the skin is bare and dry. Peel the adhesive pads from their backing and place one on the upper right chest below the collarbone, the other on the left side below the armpit. Diagrams on the pads show you exactly where they go.
The AED will automatically analyze the heart rhythm. Don’t touch the person during this step. If the device says “shock advised,” make sure nobody is touching the person and press the flashing shock button. If it says “no shock advised,” resume CPR immediately. After a shock is delivered, go right back to compressions. The AED will prompt you every two minutes to pause so it can reanalyze.
If You Suspect an Opioid Overdose
Opioid overdoses typically cause breathing to slow and eventually stop, which can then lead to cardiac arrest. If the person is unresponsive but still has a pulse, focus on opening their airway (tilt the head back, lift the chin) and giving rescue breaths. If naloxone (commonly sold as Narcan) is available, administer it. If there’s no pulse, begin full CPR and use an AED if one is nearby.
Naloxone can reverse the effects of opioids, but it takes a few minutes to work and doesn’t replace the need for CPR if the heart has stopped. Call 911 regardless of whether naloxone is available.
When to Stop
As a bystander, keep going until one of three things happens: the person starts moving or breathing on their own, emergency medical services arrive and take over, or you are physically unable to continue. CPR is exhausting. If someone else is present, switch off every two minutes to keep compressions effective.
Don’t worry about knowing when to officially “call it.” That decision belongs to medical professionals. Your job is to keep blood moving until help arrives.
Legal Protection for Bystanders
Every U.S. state has some form of Good Samaritan law that protects people who provide emergency care in good faith. If you crack a rib during CPR (which happens frequently, even when done correctly), you’re protected from civil liability as long as you acted voluntarily, responded to a genuine emergency, and didn’t act with reckless disregard for the person’s safety.
These protections generally require that the person consented to help if they were capable of consenting, that you weren’t under the influence of drugs or alcohol, and that you didn’t provide care beyond your level of training. Ordinary mistakes made while genuinely trying to help are covered. Broken ribs from chest compressions are one of the most common examples, and they’re considered a normal and expected side effect of effective CPR, not a reason for liability.