CPR & AED: What Actually Works When Someone Collapses

Imagine you are at a family gathering, and your uncle suddenly slumps to the floor. He's not breathing, or maybe he's gasping. What do you do? If you're like most people, your heart races, and a flood of doubts hits: Do I do mouth-to-mouth? How hard do I push? What if I hurt him? This is the moment where the difference between life and death is measured in minutes—and where knowing what actually works can make you the person who saves a life.

We're writing this as people who train in first aid, who have seen the data, and who know that the biggest killer in these moments is not lack of equipment—it's hesitation. The American Heart Association (AHA) reports that in the U.S., only about 40% of people who experience an out-of-hospital cardiac arrest receive bystander CPR before professional help arrives (AHA CPR Facts & Stats). That means 6 out of 10 people don't get the help they need while waiting for an ambulance. That's not because people don't care; it's because they're scared. So let's bust the myths and give you the clear, actionable facts.

Should I do mouth-to-mouth or just chest compressions?

If you see a teen or adult suddenly collapse, the answer is: skip the breaths. The AHA recommends Hands-Only CPR for teens and adults who suddenly collapse—just two steps: call 9-1-1, then push hard and fast in the center of the chest at 100 to 120 compressions per minute until help arrives (AHA Hands-Only CPR). Why? Because in sudden cardiac arrest, the person has enough oxygen in their blood for a few minutes; what they need is for you to keep that blood circulating to their brain and heart. Compressions do that. So don't waste time on breaths that might make you hesitate or do it wrong. For infants and children, however, the AHA recommends CPR with compressions and breaths (AHA Hands-Only CPR). The ratio for a single rescuer is 30 compressions to 2 breaths, just like adults, but for two rescuers it's 15:2 (UC Davis Health CPR). So, for a kid, you do need the breaths—but for an adult who collapses, just push.

How hard and how fast should I push?

Most people worry about breaking ribs. Let's be blunt: a broken rib heals; a dead person doesn't. The AHA says adult compressions should be at least 2 inches (5 cm) deep but no more than 2.4 inches (6 cm), at a rate of 100 to 120 per minute (AHA). That's about the rhythm of the Bee Gees' “Stayin' Alive” (or “Another One Bites the Dust,” if you prefer). And you must let the chest fully recoil between compressions—don't lean on the person. High-quality CPR includes full chest recoil and minimizing interruptions, with a chest compression fraction above 80% (AHA). That means if you start pushing, don't stop unless you're switching with someone else or using an AED. Even then, keep interruptions to less than 10 seconds.

What if there's an AED? Are those things safe?

Yes, they are safe, and they're lifesavers. An automated external defibrillator (AED) analyzes the heart rhythm and delivers a shock only if a shockable rhythm is detected (AED guidance). That means it won't shock someone who doesn't need it. So don't be afraid of it. Use an AED when a person is unresponsive and not breathing normally or only gasping (AED guidance). For adults and children 8 and older, place one pad on the upper right chest below the collarbone and the other on the lower left side below the armpit (AED guidance). For infants and small children, place one pad on the center of the chest and the other on the back between the shoulder blades (AED guidance). After a shock, or if no shock is advised, resume CPR immediately for about 2 minutes before the AED reanalyzes (AED guidance).

And here's a number that should make you want to find an AED: in a study published in the American Heart Association journal Circulation, victims of cardiac arrest shocked with a bystander-applied AED had a 66.5% survival rate versus 43% for those who received their first shock after EMS arrival (AHA PAD study). That's a huge difference. So if there's an AED nearby, send someone to get it while you start CPR.

Is it true that every minute without CPR or defibrillation reduces survival by 10%?

Yes, and this is the scary reality. Survival from sudden cardiac arrest drops by about 10% for every minute without CPR or defibrillation, with a rescue window of about 4 minutes (AED guidance). About 9 out of 10 people who receive an AED shock within the first minute survive, and CPR plus AED use within 3–5 minutes can raise survival to around 70% (AED guidance). That's the difference between doing something and doing nothing. More than 350,000 people in the U.S. experience out-of-hospital cardiac arrest each year (AED guidance), and most of them—about 73%—happen at home (AHA CPR Facts & Stats). So it's likely to be someone you know.

What if I do CPR and the person is just drunk or fainted? Could I hurt them?

First, check for responsiveness and normal breathing. If they are breathing normally, even if unconscious, you don't do CPR—you put them in the recovery position (NHS recovery position). But if they are not breathing or only gasping, that's cardiac arrest, and you must act. Gasping is not normal breathing; it's a sign of cardiac arrest. So if you see that, start compressions. The risk of hurting a person in cardiac arrest is low compared to the near-certain death if you do nothing. And yes, you might break a rib, but that's a minor injury compared to death.

What's the single biggest mistake people make?

Not starting. They wait, they debate, they watch, they hope someone else will take charge. The data is clear: survival drops 10% per minute. So the biggest mistake is doing nothing. The second biggest mistake is stopping too soon—either because they get tired or because they think the person is “gone.” Keep pushing until EMS arrives or the person shows signs of life. If you're exhausted, find someone to take over, but don't stop.

What I'd actually do

Here's my concrete recommendation, and I say this as someone who has been in this situation. The moment someone collapses and isn't breathing normally, I'd do three things in quick succession: (1) shout for someone to call 9-1-1 and to grab an AED if one is nearby; (2) start chest compressions immediately—hard and fast, at 100–120 per minute, 2 inches deep, letting the chest recoil; (3) as soon as the AED arrives, turn it on, follow its prompts, and after any shock, resume compressions for 2 minutes. Don't stop to check for a pulse or to see if they're “okay.” Don't worry about mouth-to-mouth for an adult. Just push. And if you're not trained, the AHA says Hands-Only CPR is still CPR—it's better than nothing. So my advice is this: take a 20-minute online course, or even just watch a video, so that when the moment comes, you're not paralyzed by fear. Because that moment will come, statistically speaking, to someone you love. And you can be the difference.

Sources

• AHA - https://cpr.heart.org
• AHA Hands-Only CPR - https://www2.heart.org/site/DocServer/Hands_Only_CPR__Empower_Yourself_and_Save_A_Life_Toolkit.pdf
• AHA CPR Facts & Stats - https://cpr.heart.org/en/resources/cpr-facts-and-stats
• AHA PAD study - https://www.ahajournals.org/doi/epdf/10.1161/CIRCULATIONAHA.109.883488
• UC Davis Health CPR - https://health.ucdavis.edu/cppn/documents/classes/cpr/Summary-of-CPR.pdf
• AED guidance - https://www.redcross.org
• NHS recovery position - https://www.nhs.uk/conditions/first-aid/recovery-position/