In modern protocols for lay persons, this step is omitted as it has been proven that lay rescuers may have difficulty in accurately determining the presence or absence of a pulse, and that, in any case, there is less risk of harm by performing chest compressions on a beating heart than failing to perform them when the heart is not beating. For this reason, lay rescuers proceed directly to cardiopulmonary resuscitation, starting with chest compressions, which is effectively artificial circulation. In order to simplify the teaching of this to some groups, especially at a basic first aid level, the C for Circulation is changed for meaning CPR or Compressions.