CPR is needed for an adult who is unresponsive and not breathing normally. Those two signs together, not a pulse check, are what should trigger you to act. The 2025 American Heart Association guidelines confirm that lay rescuers should base their decision on level of consciousness and respiratory effort rather than trying to find a pulse. If someone collapses, won’t respond when you shout and tap their shoulders, and isn’t breathing or is only making occasional gasping sounds, they need CPR immediately.
The Two Signs That Matter
Recognizing cardiac arrest doesn’t require medical training. You’re looking for exactly two things: responsiveness and breathing. If you see someone collapse or find someone who appears unconscious, shout at them and tap their shoulders firmly. If they don’t respond at all, look at their chest for normal breathing. If they’re not breathing, or if their breathing looks strange and irregular, call 911 and start chest compressions.
You do not need to check for a pulse. Even healthcare professionals are told to start CPR if they can’t definitively feel a pulse within 10 seconds. For untrained bystanders, checking a pulse wastes precious time and is unreliable. The combination of unresponsiveness and absent or abnormal breathing is enough to identify the vast majority of people in cardiac arrest.
Why Gasping Doesn’t Count as Breathing
One of the most common reasons bystanders hesitate is that the person appears to still be breathing. About 40% of people in cardiac arrest display what’s called agonal breathing: slow, irregular gasps that look like the person is struggling to breathe or making snoring, gurgling sounds. These gasps are reflexive and come from the lower brainstem as the brain loses oxygen. They do not move air effectively into the lungs.
There’s no single description that captures what agonal breathing looks like. People describe it as snorting, moaning, or fish-out-of-water gasping. The key distinction is that normal breathing is steady and rhythmic. If the breathing is sporadic, labored, or just doesn’t look right in someone who won’t wake up, treat it as cardiac arrest. Starting CPR on someone who turns out not to need it is far less dangerous than waiting while someone’s brain goes without oxygen.
Cardiac Arrest vs. Heart Attack
These two conditions are frequently confused, but only one always requires CPR. A heart attack is a circulation problem: a blocked artery cuts off blood flow to part of the heart muscle. The person is typically conscious, may be clutching their chest, and their heart is still beating. They need emergency medical help, but not CPR (unless they lose consciousness and stop breathing).
Cardiac arrest is an electrical problem. The heart suddenly stops pumping due to a malfunction in its rhythm. The person loses consciousness and their pulse within seconds. Without CPR, brain damage begins in about four to six minutes. A heart attack can sometimes trigger cardiac arrest, which is why you should still call 911 for chest pain. But if the person is awake and talking, CPR is not appropriate.
Opioid Overdose and CPR
Suspected opioid overdoses follow the same basic rule. If someone is unconscious and not breathing normally, start CPR. If you have naloxone (Narcan) available, administer it, but don’t wait to see if it works before beginning compressions. The AHA recommends that anyone who can’t reliably confirm a pulse should initiate CPR for an unconscious person who isn’t breathing normally, with naloxone given on top of that effort if overdose is suspected. If the person doesn’t respond to naloxone, continue CPR until emergency medical services arrive.
What to Do Step by Step
The American Red Cross breaks the process into a simple sequence. First, check that the scene is safe for you. Look for traffic, fire, downed power lines, or other hazards. Then check the person: shout “Are you okay?” and tap their shoulders. If there’s no response, look for normal breathing for no more than 10 seconds.
If they’re not breathing or only gasping, call 911 (or have someone nearby call) and ask for an automated external defibrillator (AED) if one is available. Then start hands-only CPR: push hard and fast in the center of the chest, aiming for a rate of 100 to 120 compressions per minute. The 911 dispatcher can walk you through it in real time.
Hands-Only CPR Is Enough
If you’re not trained in CPR or you’re uncomfortable giving rescue breaths, hands-only CPR (chest compressions without mouth-to-mouth) is the recommended approach for bystanders. The AHA encourages this method specifically because it simplifies the process and removes barriers that stop people from helping. Fear of making mistakes, fear of causing harm, and reluctance to perform mouth-to-mouth breathing are the most common reasons bystanders don’t attempt CPR at all.
Chest compression-only CPR delivers substantially more compressions per minute than the traditional method because there are no pauses for breaths. For an adult who collapses from a cardiac event, the blood still contains enough oxygen in the first several minutes to keep vital organs alive if you keep it circulating with compressions. Doing something imperfectly is dramatically better than doing nothing.
Why Bystander CPR Matters
The survival numbers make the case clearly. A large study of older adults with out-of-hospital cardiac arrest found that bystander CPR was associated with a 24% higher likelihood of surviving to hospital discharge compared to those who didn’t receive it (10.2% survival vs. 5.5%). That benefit held regardless of age, whether the person was 65 or over 85. Every minute without CPR reduces the chance of survival, so the gap between a bystander starting compressions and an ambulance arriving (typically 7 to 12 minutes) is the window where your actions have the greatest impact.
When to Stop CPR
Once you start, keep going until one of these things happens: emergency medical services arrive and take over, an AED becomes available and is ready to analyze the person’s heart rhythm, the person shows clear signs of life (moving, breathing normally, opening their eyes), or you become too physically exhausted to continue effectively. If another bystander is available, take turns so the quality of compressions stays high. Minimizing interruptions in chest compressions is one of the most important factors in giving someone the best chance of survival.
Legal Protections for Bystanders
Good Samaritan laws in all 50 states provide legal protection for bystanders who perform CPR in good faith during an emergency. If you crack a rib while doing compressions (which happens frequently and is considered normal), these laws give you a legal defense against a lawsuit. The protection covers reasonable mistakes that anyone might make while trying to help. It doesn’t grant absolute immunity, but as long as you’re acting in good faith and not being reckless, the law is on your side.