You are currently on placement in the emergency department (ED). A 55 year old city worker is bluelighted into the ED having had a cardiorespiratory arrest at work. The paramedics have been resuscitating him for 3 minutes. On arrival, he is in ventricular fibrillation. Your mentor asks you the following question prior to your shift starting: What will be the most important part of the patient’s immediate advanced life support?