Because in 2005 the International Liaison Committee on Resuscitation (ILCOR) updated a lot of the old procedures. The old standard of 15 compressions and 2 breaths was changed to 30 compressions to 2 breaths. The American Heart Association adopted the recommended changes as well.
Some of the reasons for the change included making it easier for one person to perform CPR. It also created fewer interruptions to blood flow, which maintained blood pressure longer. And it allowed for 3 sets of 30:2 in 1 minute. If you do the math, that means you could deliver 90 compressions in that one minute.
With the old standard of 15:2, the most sets you could complete in one minute was 4, which means you could only deliver 60 compressions in that minute. The 30 compressions created better perfusion of oxygen-carrying blood to the heart. This became a much more efficient way to deliver compressions and breaths for conventional CPR. Two decades later, that ratio has stood the test of time: the American Heart Association’s 2025 Guidelines keep 30:2 as the standard for adult CPR.
These 30 compressions should be delivered at a rate of 100-120 compressions per minute, pushing at least 2 inches deep and allowing the chest to fully recoil between compressions. That is very quick. I hear a lot of people suggest you should sing “Stayin’ Alive” by the Bee Gees to help keep rhythm with your compressions.
This is impractical in real life. You need to be counting to keep track of your compressions. Singing will totally confuse you. It would work if you were performing hands-only CPR, where you deliver continuous compressions with no interruptions and counting is unnecessary.
