They were released after collective concern at the lack of skill retention by individuals who had completed first aid courses, of particular worry were the many different protocols of CPR, depending on injury / non injury / child CPR / 2 person CPR. There was also some doubt raised by clinicians as to the clinical benefit of the old system (not that it was ineffective but that there may be a more efficient technique)
Hence the latest guidelines, the most striking change being 30 chest compressions where before we carried out 15.
It was noted that under the old regime of 15:2, that it could take up to 10 compressions to raise the pressure inside the chest cavity (intrathoracic pressure) to the point where oxygen perfusion would take place into the heart muscle; it follows then, only the last 5 compressions were of clinical benefit to the heart. After the 15 compressions we would give 2 rescue breaths, during which time the intrathoracic pressure would naturally drop and we would have to repeat the whole process.
With the above in mind, it was decided that instead of 15 compressions we would carry out 30. That way we could be confident that at least 20 of the 30 compressions was perfusing oxygen into the heart muscle thereby giving the casualty the best possible chance of survival.
To address the skill retention issue this change was adopted over the entire age range, from infant up through to adults – CPR suddenly got easier to understand and remember.