Final answer:
When an AED indicates 'no shock advised,' one should immediately continue or begin CPR to support blood flow until professional medical help arrives or a shockable rhythm develops.
Step-by-step explanation:
If an Automated External Defibrillator (AED) states 'no shock advised', the next step is to begin or continue cardiopulmonary resuscitation (CPR). The AED has determined that the victim does not have a shockable rhythm (like ventricular fibrillation or pulseless ventricular tachycardia) and therefore a shock would not be beneficial at this time.
However, CPR is essential as it can help maintain vital blood flow to the heart and brain until more advanced medical help arrives or until the person's heart potentially becomes shockable again. After each cycle of CPR, usually lasting about 2 minutes, the AED should be used to reassess the heart rhythm to determine if a shock is then advised.