Some manufacturers produce two versions of their AED units: Semi-Automatic and Fully Automatic.
While using a Fully Automatic AED, the AED will read a victim’s underlying heart rhythm and if they have a shockable rhythm, the AED will tell the rescuer to “Stand Clear” and will administer a shock automatically to the victim. (An AED will NOT shock an individual if they do not need it .)
A Semi-Automatic AED will read the victim’s underlying heart rhythm and if it detects a shockable rhythm, it will prompt the rescuer to push the Shock Button in order to deliver the electrical shock.
Which version should I buy?
This answer depends on who will be using the AED unit and where it will be located.
The Fully Automatic version of AEDs were created with the intention of reducing delay in administering defibrillation therapy by lay rescuers who may not be comfortable pressing a shock button. If the AED will be placed in a highly public area where bystanders, or potential rescuers may not be trained, a Fully Automatic version may be a good choice.
If the AED will be mostly used by trained rescuers, some customers opt for the Semi-Automatic version in order to have complete control of the environment surrounding the SCA victim.