What should a first responder do when an external defibrillator vest indicates that a shock is about to be delivered?

When an external defibrillator vest indicates that a shock is about to be delivered, the correct action is to continue CPR until instructed otherwise. This approach is crucial because maintaining blood circulation is vital for a patient in cardiac arrest. While the defibrillator is preparing to deliver a shock, it is important to ensure that CPR is ongoing, as it helps preserve vital organ perfusion and increases the likelihood of a successful shock.

Stopping CPR prematurely to assess the pulse or monitor the patient could lead to a deterioration in their condition, as time without adequate blood flow can be detrimental. Removing the defibrillator vest is not appropriate because it is specifically designed to deliver lifesaving shocks and should remain in place until the emergency response team has taken over or the patient is stable. Continuing CPR is the best practice, as it maximizes the chances of survival until advanced medical help arrives.