CAB stands for Compressions, Airway, Breathing, and it’s the recommended sequence for performing CPR. Instead of opening the airway first, you start with chest compressions, then clear the airway, then deliver rescue breaths. The American Heart Association made this the standard in 2010, replacing the older ABC (Airway, Breathing, Compressions) approach that had been taught for decades.
Why the Order Changed From ABC to CAB
For years, CPR training taught rescuers to open the airway and give breaths before starting chest compressions. The problem was that this delayed the most critical part of CPR. Opening the airway takes time, and many bystanders found rescue breaths intimidating or were unwilling to perform them, so they often did nothing at all.
The shift to CAB was built on a straightforward physiological reality: when someone’s heart stops, their blood still contains oxygen for a short time. Chest compressions push that oxygen-rich blood to the brain and vital organs immediately. Pausing to open the airway first wastes precious seconds when the brain is already losing blood flow. By flipping the order, compressions start sooner and ventilation is only minimally delayed.
The timing matters more than most people realize. A study published in Circulation: Cardiovascular Quality and Outcomes found that people who received CPR within one minute of cardiac arrest had significantly better outcomes than those who waited. A delay of just two to three minutes was associated with a 9% lower chance of survival. At four to five minutes, the likelihood of survival dropped by 27%, and the chance of a good neurological outcome fell by 28%.
C: Chest Compressions Come First
The “C” in CAB is chest compressions, and this is where you begin. Place the heel of one hand on the center of the person’s chest, between the nipples, and stack your other hand on top. Push hard and fast at a rate of 100 to 120 compressions per minute, which is roughly the tempo of the song “Stayin’ Alive.” Each compression should push the chest down at least 2 inches (5 centimeters) in an adult. Let the chest fully rise back up between each push so the heart can refill with blood.
The goal is to manually pump blood through the body when the heart can’t do it on its own. Every pause in compressions means the brain and heart lose blood flow, so minimizing interruptions is just as important as compression depth and speed.
A: Open the Airway
After 30 compressions, you move to the “A” step: opening the airway. This uses a technique called the head-tilt, chin-lift maneuver. Place your palm on the person’s forehead and gently tilt their head back. With your other hand, lift the chin forward. This prevents the tongue from blocking the throat, which commonly happens when someone is unconscious. If you suspect a neck injury, skip the head tilt and only lift the jaw forward.
B: Rescue Breaths
With the airway open, give two rescue breaths. Pinch the person’s nose shut, seal your mouth over theirs, and blow in just enough air to make the chest visibly rise. Each breath should take about one second. Then return immediately to chest compressions. The full cycle is 30 compressions followed by 2 breaths, repeated without stopping until emergency medical services arrive or the person starts breathing on their own.
When Hands-Only CPR Is Enough
Not every situation calls for the full CAB sequence. If you see an adult suddenly collapse and you’re not trained in CPR or you’re not confident giving rescue breaths, the AHA recommends hands-only CPR: call 911 and push hard and fast in the center of the chest without stopping. No breaths needed. This approach works well for adults who collapse from a cardiac event because, again, their blood still carries oxygen that compressions can circulate.
If you are trained and feel comfortable, you can perform the full 30:2 cycle of compressions and breaths. Both approaches are considered effective for witnessed adult cardiac arrest. The key point is that doing something, even compressions alone, is far better than doing nothing while waiting for paramedics.
There are situations, though, where rescue breaths make a bigger difference. Drowning victims, children, people who overdosed, and anyone whose cardiac arrest stems from a breathing problem rather than a heart problem will benefit from ventilation alongside compressions. Their oxygen reserves tend to be depleted before the heart stops, so breaths become more important sooner.
CAB for Children and Infants
The CAB sequence applies to children and infants too. The AHA kept the order consistent across all age groups to simplify training so rescuers don’t have to remember different sequences under pressure. A pediatric study found that starting with compressions delayed the first breath by less than six seconds compared to the old ABC approach, a tradeoff considered well worth the benefit of getting blood moving immediately.
The technique adjusts for smaller bodies. For children, compress the chest to about one-third of its depth. For infants, use two thumbs with hands encircling the chest (if two rescuers are present) or the heel of one hand for a single rescuer. The 2025 AHA guidelines dropped the older two-finger technique for infants because it didn’t reliably achieve adequate compression depth. The compression rate stays the same at 100 to 120 per minute, and the 30:2 ratio of compressions to breaths applies for single rescuers.
Why Compressions Matter Most
The entire philosophy behind CAB comes down to a simple priority: blood flow saves lives. Without compressions, no amount of airway management or breathing will help because the oxygen has no way to reach the brain. As CPR continues for longer periods, the oxygen remaining in the blood does get used up, which is why rescue breaths become increasingly important over time. But in those first critical minutes, compressions are what keep someone alive long enough for advanced medical care to arrive.