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100 to 120 compressions a minute, at least 5cm deep. The American Heart Association says immediate CPR can double or triple survival — and you do not have to give rescue breaths for it to work.
The most common reason bystanders do nothing is a belief that they will do it wrong. The guidance has been simplified specifically to remove that excuse.
The American Heart Association's version of hands-only CPR has two steps:
- Call 911 — or send someone else to do it.
- Push hard and fast in the centre of the chest.
That is the whole protocol.
The numbers that matter
Chest compressions
American Heart Association; depth range also per St John Ambulance.
100–120
compressions per minute
5–6 cm
depth — at least 2 inches, not more than 2.4
2–3×
the survival chance, when CPR starts immediately
Place the heel of one hand in the centre of the chest, your other hand on top, fingers interlocked. Keep your arms straight and push from your shoulders, not your elbows.
The rate is faster than most people guess. If it helps, it is roughly the tempo of a brisk pop song — and the reason that comparison is everywhere is that it works.
Breaths are optional
St John Ambulance sets it out plainly. If you are trained and willing, alternate 30 compressions with two rescue breaths. If you are unable or unwilling to give breaths, give continuous chest compressions instead.
That is not a lesser option offered out of politeness. For an adult who collapses suddenly, there is oxygen still in the blood; what has stopped is the pump moving it. Compressions do the moving.
The thing that reduces survival is not the absence of rescue breaths. It is pauses.
Do not stop for long
St John Ambulance's instruction is to not interrupt chest compressions for too long. Keep going until emergency services take over, the person shows signs of life, or you physically cannot continue.
If someone else is present, swap every couple of minutes. Good compressions are exhausting, and quality falls off faster than people realise.
The fear of doing harm
Two worries stop bystanders, and both are worth answering.
"What if they aren't actually in cardiac arrest?" A person who is conscious will object, loudly and immediately. Someone unresponsive and not breathing normally is not going to be harmed by compressions they did not need nearly as much as by the ones they did need and did not get.
"What if I break a rib?" It happens, at the depth required. A broken rib heals. Cardiac arrest without CPR generally does not.
The AHA's framing is worth keeping in mind: 350,000 people a year die of cardiac arrest in the United States, and immediate CPR can double or triple the chance of surviving it.
- What are the two steps of hands-only CPR?
- The American Heart Association gives them as: call 911, or send someone else to do it, then push hard and fast in the centre of the chest.
- How fast and how deep should chest compressions be?
- 100 to 120 compressions per minute. The AHA gives a depth of at least 2 inches (5cm) for an average adult, while avoiding depths greater than 2.4 inches (6cm). St John Ambulance gives 5 to 6cm.
- Do you have to give rescue breaths?
- No. St John Ambulance says that if you are unable or unwilling to give rescue breaths, give continuous chest compressions instead. If you are trained and willing, the ratio is 30 compressions to two breaths.
- Does bystander CPR actually change the outcome?
- The American Heart Association says immediate CPR can double or triple the chances of survival after cardiac arrest. It reports that 350,000 people a year die from cardiac arrest in the United States.
Yukarıdaki her rakam, aşağıdaki kaynaklardan, onların bildirdiği biçimde ve verilen tarihle alınmıştır.
- 01What is CPR
American Heart Association
- 02CPR advice
St John Ambulance
Bu kaynaklara göre doğrulama tarihi: 20 August 2026
