You should perform CPR (chest compressions with or without rescue breaths) when someone is unresponsive, not breathing normally, and has no pulse. Rescue breathing alone is the right choice when someone has stopped breathing but still has a detectable pulse. The difference comes down to one question: is the heart still beating?
How to Tell the Difference
When you find someone unresponsive, you have about 10 seconds to check two things: breathing and pulse. Tilt their head back, look for chest rise, and listen for breath sounds. At the same time, feel for a pulse at the side of the neck (the carotid artery in adults and children) or inside the upper arm (the brachial artery in infants).
If there is no pulse and no normal breathing, or only gasping, the person is in cardiac arrest. Start CPR immediately: 30 chest compressions followed by 2 rescue breaths, repeating that cycle until help arrives or an AED is available. Gasping (sometimes called agonal breathing) is not real breathing. It’s an involuntary reflex that can happen in the first minutes of cardiac arrest, and it should not stop you from starting compressions.
If there is a pulse but the person is not breathing, or breathing very slowly and shallowly, that’s a respiratory arrest. The heart is still working, so chest compressions aren’t needed yet. Rescue breathing alone can keep oxygen flowing until the person starts breathing on their own or paramedics take over.
Why the Distinction Matters
Respiratory arrest and cardiac arrest are different emergencies, but one leads to the other quickly. When breathing stops, oxygen levels in the blood drop. Within minutes, the heart can stop too. Catching a respiratory arrest early and providing rescue breaths can prevent it from becoming a cardiac arrest, which is far more dangerous.
A study published in the New England Journal of Medicine found that 43 percent of children who had a respiratory arrest (pulse still present) survived to hospital discharge. Among those who progressed to full cardiac arrest, only 6 out of 80 survived, and all had neurological damage. The gap in outcomes is dramatic, which is why recognizing the difference and acting fast is so important.
If you’re ever unsure whether you feel a pulse, err on the side of starting CPR. A systematic review of cases where people received chest compressions unnecessarily (they still had a pulse) found that fewer than 1 percent experienced any injury like a rib fracture. About 4 percent reported chest pain or discomfort afterward. No deaths were caused by the compressions themselves. The risk of doing compressions on someone who doesn’t need them is far smaller than the risk of not doing them on someone who does.
Rescue Breathing Rates by Age
When someone has a pulse but isn’t breathing, the rate of rescue breaths depends on the person’s age:
- Adults: 1 breath every 6 seconds (about 10 breaths per minute)
- Children: 1 breath every 2 to 3 seconds (about 20 to 30 breaths per minute)
- Infants: 1 breath every 2 to 3 seconds (about 20 to 30 breaths per minute)
Each breath should be just enough to make the chest visibly rise. Overinflating the lungs forces air into the stomach and can cause vomiting. Recheck the pulse every 2 minutes. If at any point you can no longer feel a pulse, switch to full CPR with chest compressions.
Scenarios Where Breathing Is the Priority
Certain emergencies are more likely to cause a respiratory arrest first, meaning the person may still have a pulse when you reach them. In these situations, rescue breaths are especially critical because the core problem is a lack of oxygen, not a heart that has stopped.
Drowning is the classic example. A drowning victim’s heart often keeps beating for several minutes after breathing stops. If you find someone pulled from the water who is unresponsive but has a pulse, start rescue breaths immediately. If there is no response to rescue breathing and no pulse is detected, begin full CPR. Current guidelines suggest starting with 2 initial rescue breaths for drowning victims before moving to compressions, since the underlying cause is oxygen deprivation.
Opioid overdoses follow a similar pattern. Drugs like fentanyl, heroin, and prescription painkillers suppress the brain’s drive to breathe. Breathing slows dramatically or stops, but the heart may still be beating. Rescue breathing (along with naloxone, if available) can bridge the gap. Again, if the pulse disappears, switch to full CPR.
Severe allergic reactions, choking that has been partially relieved, and certain poisonings can also cause breathing to fail before the heart does. In each case, the principle is the same: pulse present means rescue breaths, pulse absent means full CPR.
Infants Have a Special Threshold
For newborns and young infants, there’s an important exception to the “pulse present, no compressions” rule. If an infant’s heart rate drops below 60 beats per minute despite 30 seconds of effective rescue breathing (you can see the chest rising), you should start chest compressions even though the heart hasn’t fully stopped. A heart rate that low in an infant does not produce enough blood flow to sustain the brain and organs. The compression-to-breath ratio for infants is 30:2 with one rescuer and 15:2 with two rescuers.
When You’re Untrained or Unsure
If you haven’t been trained in CPR or you’re not confident giving rescue breaths, hands-only CPR (continuous chest compressions without breaths) is recommended by the American Heart Association for any adult who collapses suddenly. Pushing hard and fast on the center of the chest at a rate of 100 to 120 compressions per minute keeps blood circulating until paramedics arrive.
Hands-only CPR works well for adults because sudden cardiac arrest in adults is usually a heart problem, not a breathing problem. There’s typically enough residual oxygen in the blood to sustain the brain for several minutes if you keep it circulating with compressions. For children, infants, and drowning victims, rescue breaths are more important because these emergencies tend to start with an oxygen deficit. If you can give breaths, you should. If you can’t, compressions alone are still far better than doing nothing.