An item used to correct the heartbeat of a patient. When used on a patient and charged with batteries, the defibrillator has a chance to either reset Fibrillation, cause Cardiac Arrest, or cure cardiac arrest. Using any defibrillator on a human will stun them for one second.
The chance for these is depicted in the graph below, with cyan being the chance to reset fibrillation, pink being the chance to cause cardiac arrest and orange being the chance to cure it. The X axis is medical skill and the Y axis is the chance to do something (with 1 being 100%).
At medical skill below 80, the Automated External Defibrillator (AED) has better chances in all regards. At 100 medical skill, the manual defibrillator is superior. Manual defibrillator becomes perfectly safe, and is guaranteed to cure cardiac arrest and fibrillation.