It is worth discussing at which point emergency department (ED) patients enter the algorithm, given it is designed to fit any environment:
The vast majority of cardiac arrests are presented to the ED (courtesy of the ambulance service) rather than originating within the hospital.
Use of the same algorithm will most likely have begun from the time of paramedic response and occassionally sooner, for example in cases of bystander cardiopulmonary resuscitation.
Clear details regarding the circumstances, initial rhythm, current rhythm and response to CPR should be sought whilst resuscitation is continued.