These measures are performed to keep up an artificial circulation, so that vital organs still get oxygen.

For this reason, lay rescuers proceed directly to cardiopulmonary resuscitation, starting with chest compressions, which is effectively artificial circulation.

Perhaps as a result of this being less obvious, the appreciation of artificial circulation as a key factor in resuscitation lagged considerably behind the obvious need for artificial respirations.

CPR involves chest compressions at least 5 cm (2 in) deep and at a rate of at least 100 per minute in an effort to create artificial circulation by manually pumping blood through the heart.

Some trainers continue to use 'circulation' as the label for the third step in the process, since performing chest compressions is effectively artificial circulation, and when assessing patients who are breathing, assessing 'circulation' is still important.

Assessment of Circulatory system is now not usually carried out for patients who are not breathing, with first aiders now trained to go straight to chest compressions (and thus providing artificial circulation) but pulse checks may be done on less serious patients.