Regarding compression-only CPR and...

Quote:
...if you start circulating deoxygenated blood (compressions only) don't you make the brain die faster?


The most deoxygenated blood will be the blood that just sits in the brain for a period of time without circulating. The brain is highly metabolic and will suck all the oxygen from the blood inside the brain's blood vessels very quickly. If you can establish some blood flow, then you can transport blood that is still oxygenated from the rest of the body to the brain. So you're saving the person's brain, at least for a short time. Of course, without ventilation, the blood will eventually become oxygen depleted, but us lay people hope that EMS will arrive before that happens.

But oxygenation is not the only factor. Interrupting compressions also decreases effective circulation, and if you're rusty at CPR or not-so-confident, you're likely to take more time than desired to switch from compression, to mouth-to-mouth, and then back to compressions, which can seriously compromise blood flow. In this situation, steady compression-only CPR would be more effective at maintaining circulation to the brain.

Quote:
Now if you are set on doing chest compressions only and as per new standards you throw away the ABCs, by starting the compressions you will put somebody into cardiac arrest.


The ILOR did away with the pulse check because research has shown that checking the carotid is an inaccurate way of confirming the presence or absence of circulation (they said "circulation" not "heartbeat" so I assume it was on purpose). It's possible that someone could be unconcious, not moving, not breathing, and have a heartbeat, but if they're not breathing, the heart won't be beating much longer anyway.

I read a comment by a cardiologist that if you mistakenly start to do a CPR chest compression on someone with a heartbeat, they will reflexively react and you'll know to stop. It's the same principle when you do the motor portion of the GCS test on a potentially brain injured person. The person may be unconcious, but pinch them hard and they will react, like moving their hands to the point of pain. But you're right, there's the risk of inducing cardiac arrest if you compress a beating heart hard, but the probability of that happening is likely very small compared the chance of doing some good in the face of a real cardiac arrest.