Final answer:
It is true that an automated external defibrillator (AED) should be used as soon as possible in the event of a witnessed adult cardiac arrest when it is available.
Step-by-step explanation:
For the question on whether it is reasonable for an automated external defibrillator (AED) to be used as soon as possible in a case of witnessed adult cardiac arrest when the device is immediately available, the answer is True. A defibrillator delivers a significant electrical shock designed to terminate an abnormal heart rhythm known as arrhythmia and restore the heart's natural pacemaker function. Public access to AEDs greatly increases the chances of survival for individuals suffering from cardiac arrest, especially in the critical first few minutes. Although CPR is recommended before the use of an AED, the priority is to use the AED as promptly as possible if it is readily accessible.