The appropriate sequence when initiating CPR on an adult is: check the scene for safety, check for responsiveness and breathing, call 911, then start chest compressions immediately. For adults in cardiac arrest, compressions come first, followed by rescue breaths if you’re trained and willing to give them. If you’re not trained in rescue breathing, hands-only CPR (compressions without breaths) is far better than doing nothing.
Step-by-Step Sequence for Adults
Before you touch the person, make sure the scene is safe for you. Look for hazards like traffic, fire, or electrical dangers. Then follow this order:
- Check for responsiveness. Tap the person’s shoulders and shout, “Are you okay?” If they don’t respond, shout again. Look for breathing and any life-threatening bleeding.
- Call 911. If someone is with you, have them call while you start CPR. If you’re alone with a phone nearby, call first, then begin. Put the phone on speaker so the dispatcher can guide you.
- Start chest compressions. Place the heel of one hand on the center of the chest, your other hand on top, and push hard and fast. Compress 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.”
- Give rescue breaths (if trained). After 30 compressions, tilt the head back, lift the chin, and give 2 breaths. Each breath should make the chest visibly rise. Then return to compressions. Continue in cycles of 30 compressions and 2 breaths.
The 2025 American Heart Association guidelines confirm this 30:2 ratio for both lay rescuers and healthcare professionals. Keep going until emergency medical services arrive, the person starts breathing, or an AED becomes available.
Why Compressions Come First
When an adult’s heart stops, there is still oxygen in the blood for the first several minutes. The immediate problem isn’t a lack of air; it’s that blood has stopped moving. Chest compressions act as a manual pump, pushing oxygenated blood to the brain and heart. Every second of delay reduces the chance of survival, so getting compressions started quickly matters more than opening the airway first.
This is why the older “Airway-Breathing-Compressions” (A-B-C) approach was largely replaced by “Compressions-Airway-Breathing” (C-A-B) for adult cardiac arrest. Studies on training manikins found that starting with compressions shortened the time to the first chest push, which is the single most important intervention a bystander can provide. The international resuscitation science body (ILCOR) recommends beginning CPR with compressions rather than ventilations, though it acknowledges the evidence is limited.
Hands-Only CPR for Untrained Rescuers
If you’ve never been trained in CPR or you’re uncomfortable giving mouth-to-mouth, skip the breaths entirely. Push hard and fast on the center of the chest without stopping. The 2025 guidelines specifically instruct 911 dispatchers to guide untrained adult bystanders through hands-only CPR over the phone.
Hands-only CPR works well for adults because the cause of cardiac arrest is usually a heart rhythm problem, not suffocation. The residual oxygen in the lungs and blood is enough to sustain the brain for several minutes, as long as compressions keep that blood circulating. For adults, continuous compressions without pausing for breaths can actually maintain better blood flow than repeatedly stopping to ventilate.
How the Sequence Changes for Children and Infants
Children and infants are different. Their cardiac arrests are more often caused by breathing problems (choking, drowning, respiratory illness) rather than a heart rhythm malfunction. By the time the heart stops, oxygen levels are already dangerously low. For these victims, rescue breaths are a critical part of CPR, and the guidelines instruct 911 dispatchers to walk bystanders through conventional CPR with breaths for children.
The compression technique also changes. For infants, use two fingers on the center of the chest and compress about 1.5 inches deep. For children, you may use one or two hands depending on the child’s size, compressing at least one-third the depth of the chest. The 30:2 ratio of compressions to breaths stays the same for a single rescuer.
One important timing difference: if you’re alone and you find a child who has already collapsed (you didn’t see it happen), perform CPR for about two minutes before stopping to call 911. The logic is that these children likely need oxygen immediately, and two minutes of CPR can bridge the gap. If you witnessed the child suddenly collapse, call 911 first, since a sudden collapse in a child is more likely to be a heart rhythm issue similar to adults.
When and How to Use an AED
An automated external defibrillator should be applied as soon as one is available. Don’t wait for a specific number of compression cycles. If a second person is present, have them retrieve the AED while you continue compressions. The device will give voice prompts telling you exactly what to do.
Once the AED analyzes the heart rhythm and delivers a shock, resume chest compressions immediately for two more minutes before the device checks the rhythm again. Pauses in compressions should be as brief as possible. Even a pulse check should take no more than 10 seconds, since longer pauses reduce the percentage of time blood is actually flowing, which correlates directly with survival.
Compression Quality Matters More Than Perfection
The most common mistakes during CPR aren’t about getting the sequence wrong. They’re about compressing too shallowly, too slowly, or stopping too often. The target is at least 2 inches deep for adults, at a rate of 100 to 120 per minute. Let the chest fully recoil between compressions so the heart can refill with blood. Aim to spend at least 80% of the total CPR time actively compressing.
If you’re giving rescue breaths, the head-tilt, chin-lift maneuver (tilting the forehead back with one hand while lifting the chin with the other) opens the airway effectively about 91% of the time. Each breath should last about one second and deliver just enough air to make the chest rise. Overinflating pushes air into the stomach and increases the risk of vomiting.
CPR is physically exhausting. If another bystander is available, switch off every two minutes to keep compression quality high. Fatigue sets in faster than most people expect, and shallow compressions don’t generate enough blood flow to matter.