The question seems to confuse two separate safety devices. An Automated External Defibrillator (AED) is a device for emergency cardiac care, not for shutting off fuel flow. A specific shut-off mechanism's name will vary based on the application it's designed for.
The handheld device used to shut off fuel flow if the operator becomes incapacitated is not explicitly mentioned in the provided reference text. However, the reference describes an Automated External Defibrillator (AED), which is a portable device that provides verbal instructions and can deliver an electric shock to the heart during a sudden cardiac arrest. This life-saving device is designed for emergencies and is commonly found in public places. An AED can be vital in the first few minutes following a cardiac arrest.
A device that shuts off fuel flow for incapacitated operators is likely a different safety mechanism with a specific name depending on the machine or vehicle it's installed in. It is not standardly called an AED or related typically to medical equipment like defibrillators.